Evaluating a novel accelerated free-breathing late gadolinium enhancement imaging sequence for assessment of myocardial injury

INTRODUCTION

Cardiac magnetic resonance imaging (MRI), including late gadolinium enhancement (LGE), plays an important role in the diagnosis and prognostication of ischemic and non-ischemic myocardial injury. Conventional LGE sequences require patients to perform multiple breath-holds and require long acquisition times. In this study, we compare image quality and assessment of myocardial LGE using an accelerated free-breathing sequence to the conventional standard-of-care sequence.

METHODS

In this prospective cohort study, a total of 41 patients post Coronavirus 2019 (COVID-19) infection were included. Studies were performed on a 1.5 Tesla scanner with LGE imaging acquired using a conventional inversion recovery rapid gradient echo (conventional LGE) sequence followed by the novel accelerated free-breathing (FB-LGE) sequence. Image quality was visually scored (ordinal scale from 1 to 5) and compared between conventional and free-breathing sequences using the Wilcoxon rank sum test. Presence of per-segment LGE was identified according to the American Heart Association 16-segment myocardial model and compared across both conventional LGE and FB-LGE sequences using a two-sided chi-square test. The perpatient LGE extent was also evaluated using both sequences and compared using the Wilcoxon rank sum test. Interobserver variability in detection of per-segment LGE and per-patient LGE extent was evaluated using Cohen's kappa statistic and interclass correlation (ICC), respectively.

RESULTS

The mean acquisition time for the FB-LGE sequence was 17 s compared to 413 s for the conventional LGE sequence (P < 0.001). Assessment of image quality was similar between both sequences (P = 0.19). There were no statistically significant differences in LGE assessed using the FB-LGE versus conventional LGE on a per-segment (P = 0.42) and per-patient (P = 0.06) basis. Interobserver variability in LGE assessment for FB-LGE was good for per-segment (= 0.71) and per-patient extent (ICC = 0.92) analyses.

CONCLUSIONS

The accelerated FB-LGE sequence performed comparably to the conventional standard-of-care LGE sequence in a cohort of patients post COVID-19 infection in a fraction of the time and without the need for breath-holding. Such a sequence could impact clinical practice by increasing cardiac MRI throughput and accessibility for frail or acutely ill patients unable to perform breath-holding.

Validation of the European SCORE2 models in a Canadian primary care cohort

AIMS

Systematic Coronary Risk Evaluation Model 2 (SCORE2) was recently developed to predict atherosclerotic cardiovascular disease (ASCVD) in Europe. Whether these models could be used outside of Europe is not known. The objective of this study was to test the validity of SCORE2 in a large Canadian cohort.

METHODS AND RESULTS

A primary care cohort of persons with routinely collected electronic medical record data from 1 January 2010 to 31 December 2014, in Ontario, Canada, was used for validation. The SCORE2 models for younger persons (YP) were applied to 57 409 individuals aged 40-69 while the models for older persons (OPs) were applied to 9885 individuals 70-89 years of age. Five-year ASCVD predictions from both the uncalibrated and low-risk region recalibrated SCORE2 models were evaluated. The C-statistic for SCORE2-YP was 0.74 in women and 0.69 in men. The uncalibrated SCORE2-YP overestimated risk by 17% in women and underestimated by 2% in men. In contrast, the low-risk region recalibrated model demonstrated worse calibration, overestimating risk by 100% in women and 36% in men. The C-statistic for SCORE2-OP was 0.64 and 0.62 in older women and men, respectively. The uncalibrated SCORE2-OP overestimated risk by more than 100% in both sexes. The low-risk region recalibrated model demonstrated improved calibration but still overestimated risk by 60% in women and 13% in men.

CONCLUSION

The performance of SCORE2 to predict ASCVD risk in Canada varied by age group and depended on whether regional calibration was applied. This underscores the necessity for validation assessment of SCORE2 prior to implementation in new jurisdictions.

Impaired coronary microvascular reactivity in youth with bipolar disorder

BACKGROUND

Cardiovascular disease (CVD) is excessively prevalent and premature in bipolar disorder (BD), even after controlling for traditional cardiovascular risk factors. The increased risk of CVD in BD may be subserved by microvascular dysfunction. We examined coronary microvascular function in relation to youth BD.

METHODS

Participants were 86 youth, ages 13-20 years (n = 39 BD, n = 47 controls). Coronary microvascular reactivity (CMVR) was assessed using quantitative T2 magnetic resonance imaging during a validated breathing-paradigm. Quantitative T2 maps were acquired at baseline, following 60-s of hyperventilation, and every 10-s thereafter during a 40-s breath-hold. Left ventricular structure and function were evaluated based on 12-15 short- and long-axis cardiac-gated cine images. A linear mixed-effects model that controlled for age, sex, and body mass index assessed for between-group differences in CMVR (time-by-group interaction).

RESULTS

The breathing-paradigm induced a significant time-related increase in T2 relaxation time for all participants (i.e. CMVR; β = 0.36, p < 0.001). CMVR was significantly lower in BD v. controls (β = -0.11, p = 0.002). Post-hoc analyses found lower T2 relaxation time in BD youth after 20-, 30-, and 40 s of breath-holding (d = 0.48, d = 0.72, d = 0.91, respectively; all pFDR < 0.01). Gross left ventricular structure and function (e.g. mass, ejection fraction) were within normal ranges and did not differ between groups.

CONCLUSION

Youth with BD showed evidence of subclinically impaired coronary microvascular function, despite normal gross cardiac structure and function. These results converge with prior findings in adults with major depressive disorder and post-traumatic stress disorder. Future studies integrating larger samples, prospective follow-up, and blood-based biomarkers are warranted.

Comparing Costs of Noninvasive Cardiac Diagnostic Tests-a Population-Based Study

INTRODUCTION

Noninvasive cardiac diagnostic tests (NITs) for the diagnosis of coronary artery disease have been estimated to cost >$3 billion annually in the United States alone and have recently undergone scrutiny over concerns of overuse. Consequently, comparing costs of different NIT testing strategies is of urgent importance to health care planning.

METHODS

We utilized population-based administrative and clinical data from Ontario, Canada, to compare downstream costs between 4 available NIT testing strategies (graded exercise stress testing [GXT], stress echocardiography, cardiac computed tomography angiography [CCTA], and myocardial perfusion imaging [MPI] as well as no testing), among patients evaluated for chest pain. To compare costs among the tested (overall and by testing strategy) and nontested groups, we used a log-gamma generalized linear model to account for the skewed distribution of health care cost data, adjusting for relevant clinical covariates.

RESULTS

A total of 2,340,699 patients were included in our cohort, of whom 481,170 (21%) patients received 1 of the 4 NITs. Among patients who received a NIT, 254,492 (53%) received a GXT as their initial test, 154,137 (32%) received MPI, 69,160 (14%) received a stress echo, and 3,381 (<1%) received a CCTA. After adjustment for differences in baseline patient characteristics, receipt of any NIT was associated with an approximate 12% reduction in downstream 1-year mean costs (cost ratio = 0.88; 95% CI, 0.87, 0.89) compared with those without any testing. Comparing the different testing strategies with no testing, both GXT (cost ratio = 0.80; 95% CI, 0.79-0.81) and stress echocardiography (cost ratio = 0.82; 95% CI, 0.81-0.83) were associated with the lower downstream costs, while both MPI (cost ratio = 1.26; 95% CI, 1.25, 1.27) and CCTA (cost ratio = 1.29; 95% CI, 1.23, 1.35) were associated with higher downstream costs.

CONCLUSIONS

In a large population-based cohort consisting of >2 million people evaluated for chest pain, we report that receipt of noninvasive testing was associated with a 12% reduction in downstream costs when compared with no testing. Graded exercise stress testing and stress echocardiography were associated with the least downstream costs, whereas CCTA and MPI were associated with higher costs when compared with no testing. These findings may help inform testing decisions in chest pain patients.

Low Prevalence of Late Myocardial Injury on Cardiac MRI Following COVID-19 Infection

BACKGROUND

The prevalence of abnormal cardiac magnetic resonance imaging (MRI) findings indicative of myocardial injury in patients who recovered from coronavirus disease 2019 (COVID-19) is currently unclear, with a high variability in the reported prevalence.

PURPOSE

To assess the prevalence of myocardial injury after a COVID-19 infection.

STUDY TYPE

Prospective, bicentric study.

SUBJECTS

Seventy consecutive patients who recovered from COVID-19 and were previously hospitalized. Mean age was 57 years and 39% of the patients were female. Ten healthy controls and a comparator group of 75 nonischemic cardiomyopathy (NICM) patients were employed.

FIELD STRENGTH/SEQUENCE

1.5-T, steady-state free precession (SSFP) gradient-echo sequence, modified Look-Locker inversion recovery sequence with balanced SSFP readout, T2-prepared spiral readout sequence and a T1-weighted inversion recovery fast gradient-echo sequence was acquired ~4-5 months after recovery from COVID-19.

ASSESSMENT

The SSFP sequence was utilized for the calculation of left and right ventricular volumes and ejection fractions (LVEF and RVEF) following manual endocardial contouring. T1 and T2 mapping was performed by pixel-wise exponential fitting, and T1 and T2 values were computed by manual contouring of the left ventricular endocardial and epicardial walls. Late gadolinium enhancement (LGE) images were graded qualitatively as LGE present or absent.

STATISTICAL TESTS

T-tests and the χ2 or Fisher's exact tests were used to compare continuous and categorical variables respectively between the COVID-19 and NICM groups. Inter-rater agreement was evaluated by the intraclass correlation coefficient for continuous variables and Cohen's kappa test for LGE.

RESULTS

Reduced RVEF occurred in 10%, LGE and elevated native T1 in 9%, reduced LVEF in 4%, and elevated T2 in 3% of COVID-19 patients, respectively. Patients with NICM had lower mean LVEF (41.6% ± 6% vs. 60% ± 7%), RVEF (46% ± 5% vs. 61% ± 9%), and a significantly higher prevalence of LGE (27% vs. 9%) when compared to those post-COVID-19.

DATA CONCLUSION

Abnormal cardiac MRI findings may show a low prevalence in patients who recovered from COVID-19 and were previously hospitalized.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY: Stage 2.

Association of neighbourhood-level material deprivation with adverse outcomes and processes of care among patients with heart failure in a single-payer healthcare system: A population-based cohort study

AIM

We studied the association between neighbourhood material deprivation, a metric estimating inability to attain basic material needs, with outcomes and processes of care among incident heart failure patients in a universal healthcare system.

METHODS AND RESULTS

In a population-based retrospective study (2007-2019), we examined the association of material deprivation with 1-year all-cause mortality, cause-specific hospitalization, and 90-day processes of care. Using cause-specific hazards regression, we quantified the relative rate of events after multiple covariate adjustment, stratifying by age ≤65 or ≥66 years. Among 395 763 patients (median age 76 [interquartile range 66-84] years, 47% women), there was significant interaction between age and deprivation quintile for mortality/hospitalization outcomes (p ≤ 0.001). Younger residents (age ≤65 years) of the most versus least deprived neighbourhoods had higher hazards of all-cause death (hazard ratio [HR] 1.19, 95% confidence interval [CI] 1.10-1.29]) and cardiovascular hospitalization (HR 1.29 [95% CI 1.19-1.39]). Older individuals (≥66 years) in the most deprived neighbourhoods had significantly higher hazard of death (HR 1.11 [95% CI 1.08-1.14]) and cardiovascular hospitalization (HR 1.13 [95% CI 1.09-1.18]) compared to the least deprived. The magnitude of the association between deprivation and outcomes was amplified in the younger compared to the older age group. More deprived individuals in both age groups had a lower hazard of cardiology visits and advanced cardiac imaging (all p < 0.001), while the most deprived of younger ages were less likely to undergo implantable cardioverter-defibrillator/cardiac resynchronization therapy-pacemaker implantation (p = 0.023), compared to the least deprived.

CONCLUSION

Patients with newly-diagnosed heart failure residing in the most deprived neighbourhoods had worse outcomes and reduced access to care than those less deprived.

Association of Neighborhood-Level Marginalization With Health Care Use and Clinical Outcomes Following Hospital Discharge in Patients Who Underwent Coronary Catheterization for Acute Myocardial Infarction in a Single-Payer Health Care System

BACKGROUND

Canadian data suggest that patients of lower socioeconomic status with acute myocardial infarction receive less beneficial therapy and have worse clinical outcomes, raising questions regarding care disparities even in universal health care systems. We assessed the contemporary association of marginalization with clinical outcomes and health services use.

METHODS

Using clinical and administrative databases in Ontario, Canada, we conducted a population-based study of patients aged ≥65 years hospitalized for their first acute myocardial infarction between April 1, 2010 and March 1, 2019. Patients receiving cardiac catheterization and surviving 7 days postdischarge were included. Our primary exposure was neighborhood-level marginalization, a multidimensional socioeconomic status metric. Neighborhoods were categorized by quintile from Q1 (least marginalized) to Q5 (most marginalized). Our primary outcome was all-cause mortality. A proportional hazards regression model with a robust variance estimator was used to quantify the association of marginalization with outcomes, adjusting for risk factors, comorbidities, disease severity, and regional cardiologist supply.

RESULTS

Among 53 841 patients (median age, 75 years; 39.1% female) from 20 640 neighborhoods, crude 1- and 3-year mortality rates were 7.7% and 17.2%, respectively. Patients in Q5 had no significant difference in 1-year mortality (hazard ratio [HR], 1.08 [95% CI, 0.95-1.22]), but greater mortality over 3 years (HR, 1.13 [95% CI, 1.03-1.22]) compared with Q1. Over 1 year, we observed differences between Q1 and Q5 in visits to primary care physicians (Q1, 96.7%; Q5, 93.7%) and cardiologists (Q1, 82.6%; Q5, 72.6%), as well as diagnostic testing. There were no differences in secondary prevention medications dispensed or medication adherence at 1 year.

CONCLUSIONS

In older patients with acute myocardial infarction who survived to hospital discharge, those residing in the most marginalized neighborhoods had a greater long-term risk of mortality, less specialist care, and fewer diagnostic tests. Yet, there were no differences across socioeconomic status in prescription medication use and adherence.

Development and Validation of the CANHEART Population-Based Laboratory Prediction Models for Atherosclerotic Cardiovascular Disease

BACKGROUND

Prediction of atherosclerotic cardiovascular disease (ASCVD) in primary prevention assessments exclusively with laboratory results may facilitate automated risk reporting and improve uptake of preventive therapies.

OBJECTIVE

To develop and validate sex-specific prediction models for ASCVD using age and routine laboratory tests and compare their performance with that of the pooled cohort equations (PCEs).

DESIGN

Derivation and validation of the CANHEART (Cardiovascular Health in Ambulatory Care Research Team) Lab Models.

SETTING

Population-based cohort study in Ontario, Canada.

PARTICIPANTS

A derivation and internal validation cohort of adults aged 40 to 75 years without cardiovascular disease from April 2009 to December 2015; an external validation cohort of primary care patients from January 2010 to December 2014.

MEASUREMENTS

Age and laboratory predictors measured in the outpatient setting included serum total cholesterol, high-density lipoprotein cholesterol, triglycerides, hemoglobin, mean corpuscular volume, platelets, leukocytes, estimated glomerular filtration rate, and glucose. The ASCVD outcomes were defined as myocardial infarction, stroke, and death from ischemic heart or cerebrovascular disease within 5 years.

RESULTS

Sex-specific models were developed and internally validated in 2 160 497 women and 1 833 147 men. They were well calibrated, with relative differences less than 1% between mean predicted and observed risk for both sexes. The c-statistic was 0.77 in women and 0.71 in men. External validation in 31 697 primary care patients showed a relative difference less than 14% and an absolute difference less than 0.3 percentage points in mean predicted and observed risks for both sexes. The c-statistics for the laboratory models were 0.72 for both sexes and were not statistically significantly different from those for the PCEs in women (change in c-statistic, -0.01 [95% CI, -0.03 to 0.01]) or men (change in c-statistic, -0.01 [CI, -0.04 to 0.02]).

LIMITATION

Medication use was not available at the population level.

CONCLUSION

The CANHEART Lab Models predict ASCVD with similar accuracy to more complex models, such as the PCEs.

PRIMARY FUNDING SOURCE

Canadian Institutes of Health Research.

Structured Cardiac Assessment Outperforms Visual Estimation in Novice Ultrasound Users: A Randomized Controlled Trial

BACKGROUND

Two evidence-based techniques to determine left ventricular (LV) systolic function are taught in emergency medicine curricula. The first is a "structured approach," which qualitatively evaluates LV fractional shortening, E-point septal separation, and LV diameter. The other is the "eyeball method," which qualitatively estimates the LV ejection fraction (LVEF).

OBJECTIVE

The aim of this study was to determine whether the structured approach or the eyeball method was superior for teaching LVEF estimation to novices.

METHODS

Medical students were recruited to participate in our randomized controlled trial. Participants were randomized to the structured approach group or eyeball method group and completed one of two 15-min educational modules. Participants subsequently interpreted 12 echocardiogram clips to determine LV function. The primary outcome was the percentage of correct interpretations as determined by a cardiologist.

RESULTS

Seventy-four participants were invited to participate and 32 completed the study (15 in the structured approach and 17 in the eyeball method groups). The majority (30 of 32 [93.75%]) were first- and second-year medical students with no prior ultrasound training. The mean time to complete the training was similar between groups (16.8 vs. 17.8 min; p = 0.66). The primary outcome of percent of correct interpretations was significantly higher in the structured approach group compared with the eyeball method group (88.9% vs. 73.0%; p < 0.01).

CONCLUSIONS

Training novice ultrasound users in a structured qualitative LV assessment method was more effective than the eyeball method. Learners were able to achieve high accuracy after a brief training intervention. These results may help inform best practices for undergraduate ultrasound curriculum development.

A Case of Recurrent Myocarditis After COVID-19 Vaccination, Due to Acute Myeloid Leukemia

A 25-year-old man presented with chest pain and an elevated troponin level following COVID-19 vaccination. Despite initial response to nonsteroidal anti-inflammatory drugs, he developed a recurrent and relapsing course requiring multiple readmissions. Cardiac magnetic resonance imaging confirmed myocarditis. Due to progressing macrocytic anemia, he was eventually diagnosed with acute myeloid leukemia, thought to be the underlying driver of his recurrent and persistent myocarditis.

Utilization and impact of cardiovascular magnetic resonance on patient management in heart failure: insights from the SCMR Registry

BACKGROUND

Cardiovascular magnetic resonance (CMR) is an important diagnostic test used in the evaluation of patients with heart failure (HF). However, the demographics and clinical characteristics of those undergoing CMR for evaluation of HF are unknown. Further, the impact of CMR on subsequent HF patient care is unclear. The goal of this study was to describe the characteristics of patients undergoing CMR for HF and to determine the extent to which CMR leads to changes in downstream patient management by comparing pre-CMR indications and post-CMR diagnoses.

METHODS

We utilized the Society for Cardiovascular Magnetic Resonance (SCMR) Registry as our data source and abstracted data for patients undergoing CMR scanning for HF indications from 2013 to 2019. Descriptive statistics (percentages, proportions) were performed on key CMR and clinical variables of the patient population. The Fisher's exact test was used when comparing categorical variables. The Wilcoxon rank sum test was used to compare continuous variables.

RESULTS

3,837 patients were included in our study. 94% of the CMRs were performed in the United States with China, South Korea and India also contributing cases. Median age of HF patients was 59.3 years (IQR, 47.1, 68.3 years) with 67% of the scans occurring on women. Almost 2/3 of the patients were scanned on 3T CMR scanners. Overall, 49% of patients who underwent CMR scanning for HF had a change between the pre-test indication and post CMR diagnosis. 53% of patients undergoing scanning on 3T had a change between the pre-test indication and post CMR diagnosis when compared to 44% of patients who were scanned on 1.5T (p < 0.01).

CONCLUSION

Our results suggest a potential impact of CMR scanning on downstream diagnosis of patients referred for CMR for HF, with a larger potential impact on those scanned on 3T CMR scanners.

TAVR in a Patient With Anomalous Origin and Course of the Left Main Coronary Artery

In patients with anomalous coronary arteries with high-risk features, corrective cardiac surgery should be considered. We report the first case of transcatheter aortic valve replacement using a self-expanding Evolut valve, in a patient with a single coronary artery arising from the right coronary cusp and an intramural course of the left main. (Level of Difficulty: Intermediate.).

A Deep Learning Segmentation Pipeline for Cardiac T1 Mapping Using MRI Relaxation-based Synthetic Contrast Augmentation

PURPOSE

To design and evaluate an automated deep learning method for segmentation and analysis of cardiac MRI T1 maps with use of synthetic T1-weighted images for MRI relaxation-based contrast augmentation.

MATERIALS AND METHODS

This retrospective study included MRI scans acquired between 2016 and 2019 from 100 patients (mean age ± SD, 55 years ± 13; 72 men) across various clinical abnormalities with use of a modified Look-Locker inversion recovery, or MOLLI, sequence to quantify native T1 (T1_native), postcontrast T1 (T1_post), and extracellular volume (ECV). Data were divided into training (n = 60) and internal (n = 40) test subsets. "Synthetic" T1-weighted images were generated from the T1 exponential inversion-recovery signal model at a range of optimal inversion times, yielding high blood-myocardium contrast, and were used for contrast-based image augmentation during training and testing of a convolutional neural network for myocardial segmentation. Automated segmentation, T1, and ECV were compared with experts with use of Dice similarity coefficients (DSCs), correlation coefficients, and Bland-Altman analysis. An external test dataset (n = 147) was used to assess model generalization.

RESULTS

Internal testing showed high myocardial DSC relative to experts (0.81 ± 0.08), which was similar to interobserver DSC (0.81 ± 0.08). Automated segmental measurements strongly correlated with experts (T1_native, R = 0.87; T1_post, R = 0.91; ECV, R = 0.92), which were similar to interobserver correlation (T1_native, R = 0.86; T1_post, R = 0.94; ECV, R = 0.95). External testing showed strong DSC (0.80 ± 0.09) and T1_native correlation (R = 0.88) between automatic and expert analysis.

CONCLUSION

This deep learning method leveraging synthetic contrast augmentation may provide accurate automated T1 and ECV analysis for cardiac MRI data acquired across different abnormalities, centers, scanners, and T1 sequences.Keywords: MRI, Cardiac, Tissue Characterization, Segmentation, Convolutional Neural Network, Deep Learning Algorithms, Machine Learning Algorithms, Supervised Learning Supplemental material is available for this article. © RSNA, 2022.

Association of Neighborhood-Level Material Deprivation With Atrial Fibrillation Care in a Single-Payer Health Care System: A Population-Based Cohort Study

BACKGROUND

There are limited data on the association of material deprivation with clinical care and outcomes after atrial fibrillation (AF) diagnosis in jurisdictions with universal health care.

METHODS

This was a population-based cohort study of individuals ≥66 years of age with first diagnosis of AF between April 1, 2007, and March 31, 2019, in the Canadian province of Ontario, which provides public funding and prohibits private payment for medically necessary physician and hospital services. Prescription medications are subsidized for residents >65 years of age. The primary exposure was neighborhood material deprivation, a metric derived from Canadian census data to estimate inability to attain basic material needs. Neighborhoods were categorized by quintile from Q1 (least deprived) to Q5 (most deprived). Cause-specific hazards regression was used to study the association of material deprivation quintile with time to AF-related adverse events (death or hospitalization for stroke, heart failure, or bleeding), clinical services (physician visits, cardiac diagnostics), and interventions (anticoagulation, cardioversion, ablation) while adjusting for individual characteristics and regional cardiologist supply.

RESULTS

Among 347 632 individuals with AF (median age 79 years, 48.9% female), individuals in the most deprived neighborhoods (Q5) had higher prevalence of cardiovascular disease, risk factors, and noncardiovascular comorbidity relative to residents of the least deprived neighborhoods (Q1). After adjustment, Q5 residents had higher hazards of death (hazard ratio [HR], 1.16 [95% CI, 1.13-1.20]) and hospitalization for stroke (HR, 1.16 [95% CI, 1.07-1.27]), heart failure (HR, 1.14 [95% CI, 1.11-1.18]), or bleeding (HR, 1.16 [95% CI, 1.07-1.25]) relative to Q1. There were small differences across quintiles in primary care physician visits (HR, Q5 versus Q1, 0.91 [95% CI, 0.89-0.92]), echocardiography (HR, Q5 versus Q1, 0.97 [95% CI, 0.96-0.99]), and dispensation of anticoagulation (HR, Q5 versus Q1, 0.97 [95% CI, 0.95-0.98]). There were more prominent disparities for Q5 versus Q1 in cardiologist visits (HR, 0.84 [95% CI, 0.82-0.86]), cardioversion (HR, 0.80 [95% CI, 0.76-0.84]), and ablation (HR, 0.45 [95% CI, 0.30-0.67]).

CONCLUSIONS

Despite universal health care and prescription medication coverage, residents of more deprived neighborhoods were less likely to visit cardiologists or receive rhythm control interventions after AF diagnosis, even though they exhibited higher cardiovascular disease burden and higher risk of adverse outcomes.

Patient, physician and geographic predictors of cardiac stress testing strategy in Ontario, Canada: a population-based study

OBJECTIVES

To identify patient, physician and geographic level factors that are associated with variation in initial stress testing strategy in patients evaluated for chest pain.

DESIGN

Retrospective cohort study.

SETTING

Population-based study of patients undergoing evaluation for chest pain in Ontario, Canada between 1 January 2011 and 31 March 2018.

PARTICIPANTS

103 368 patients who underwent stress testing (graded exercise stress testing (GXT), stress echocardiography (stress echo) or myocardial perfusion imaging (MPI)) following evaluation for chest pain.

PRIMARY AND SECONDARY OUTCOME MEASURES

To identify the patient, physician and geographic level factors associated with variation in initial test selection, we fit two separate 2-level hierarchical multinomial logistic regression models for which the outcome was initial stress testing strategy (GXT, MPI or stress echo).

RESULTS

There was significant variability in the initial type of stress test performed, with approximately 50% receiving a GXT compared with approximately 36% who received MPI and 14% who received a stress echo. Physician-level factors were key drivers of this variation, accounting for up to 59.0% of the variation in initial testing. Physicians who graduated medical school >30 years ago were approximately 45% more likely to order an initial stress echo (OR 1.45, 95% CI 1.17 to 1.80) than a GXT. Cardiovascular disease specialists were approximately sevenfold more likely to order an initial MPI (OR 7.35, 95% CI 5.38 to 10.03) than a GXT. Patients aged >70 years were approximately fivefold more likely to receive an MPI (OR 4.74, 95% CI 4.42 to 5.08) and approximately 26% more likely to receive a stress echo (OR 1.26, 95% CI 1.15 to 1.38) than a GXT.

CONCLUSIONS

We report significant variability in initial stress testing strategy in Ontario. Much of that variability was driven by physician-level factors that could potentially be addressed through educational campaigns geared at reducing this variability and improving guideline adherence.

Incidental Findings Among Youth Participating in Multimodal Imaging Research: Characteristics of Findings and Description of a Management Approach

Research imaging in healthy and clinical youth populations yields incidental findings that require a management strategy. Our primary objective was to document the frequency and nature of incidental findings within a research group integrating multiple imaging modalities. A second objective was to describe the evolution of an approach to handling incidental findings. A case example was included to display the intricacies of some of these scenarios. Youth, ages 13-20 years, with bipolar disorder, familial risk for bipolar disorder, or healthy controls, obtained one or a combination of neuroimaging, cardio-thoracic imaging, retinal imaging, and carotid imaging. All images were systematically reviewed for incidental findings. Overall, of 223 participants (n = 102 healthy controls), 59% (n = 131) had a brain magnetic resonance imaging (MRI) incidental finding and 27% (n = 60) had at least one incidental brain finding requiring non-urgent follow-up. In addition, of 109 participants with chest/cardiac MRI and carotid ultrasound, 3% (n = 3) had chest findings, 2% (n = 2) had cardiac findings, and 1% (n = 1) had a carotid finding. Of 165 youth with retinal imaging, 1% (n = 2) had incidental findings. While the vast majority of these incidental findings were of a non-serious, non-urgent nature, there were noteworthy exceptions. Imaging research groups need a system that emphasizes the value of clinical review of research images and one that is collaborative and responsive in order to inform follow-up plans. Rating systems that have been developed and used in neuroimaging for the classification of incidental findings can be adapted for use in areas other than the brain. Regardless of severity, incidental findings may raise anxiety in youth participants and their parents. The optimal threshold is one that balances transparency with utility.

Impact of COVID-19 Pandemic on Cardiovascular Testing in Asia

Background

The coronavirus disease-2019 (COVID-19) pandemic significantly affected management of cardiovascular disease around the world. The effect of the pandemic on volume of cardiovascular diagnostic procedures is not known.

Objectives

This study sought to evaluate the effects of the early phase of the COVID-19 pandemic on cardiovascular diagnostic procedures and safety practices in Asia.

Methods

The International Atomic Energy Agency conducted a worldwide survey to assess changes in cardiovascular procedure volume and safety practices caused by COVID-19. Testing volumes were reported for March 2020 and April 2020 and were compared to those from March 2019. Data from 180 centers across 33 Asian countries were grouped into 4 subregions for comparison.

Results

Procedure volumes decreased by 47% from March 2019 to March 2020, showing recovery from March 2020 to April 2020 in Eastern Asia, particularly in China. The majority of centers cancelled outpatient activities and increased time per study. Practice changes included implementing physical distancing and restricting visitors. Although COVID testing was not commonly performed, it was conducted in one-third of facilities in Eastern Asia. The most severe reductions in procedure volumes were observed in lower-income countries, where volumes decreased 81% from March 2019 to April 2020.

Conclusions

The COVID-19 pandemic in Asia caused significant reductions in cardiovascular diagnostic procedures, particularly in low-income countries. Further studies on effects of COVID-19 on cardiovascular outcomes and changes in care delivery are warranted.

Right Ventricular Function at Cardiac MRI Predicts Cardiovascular Events in Patients with an Implantable Cardioverter-Defibrillator

Background Right ventricular ejection fraction (RVEF) is an independent predictor of death and adverse cardiovascular outcomes in patients with various cardiac conditions. Purpose To investigate whether RVEF, measured with cardiac MRI, is a predictor of appropriate shock or death in implantable cardioverter-defibrillator (ICD) recipients for primary and secondary prevention of sudden cardiac death. Materials and Methods This retrospective, multicenter, observational study included patients who underwent cardiac MRI before ICD implantation between January 2007 and May 2017. Right ventricular end-diastolic and end-systolic volumes and RVEF were measured with cardiac MRI. The primary end point was a composite of all-cause mortality or appropriate ICD shock. The secondary end point was all-cause mortality. The association between RVEF and primary and secondary outcomes was evaluated by using multivariable Cox regression analysis. Potential interactions were tested between primary prevention, ischemic cause, left ventricular ejection fraction (LVEF), and RVEF. Results Among 411 patients (mean age ± standard deviation, 60 years; 315 men) during a median follow-up of 63 months, 143 (35%) patients experienced an appropriate ICD shock or died. In univariable analysis, lower RVEF was associated with greater risks for appropriate ICD shock or death and for death alone (log-rank trend test, P = .003 and .005 respectively). In multivariable Cox regression analysis adjusting for age at ICD implantation, LVEF, ICD indication (primary vs secondary), ischemic heart disease, and late gadolinium enhancement, RVEF was an independent predictor of the primary outcome (hazard ratio [HR], 1.21 per 10% lower RVEF; 95% CI: 1.04, 1.41; P = .01) and all-cause mortality (HR, 1.25 per 10% lower RVEF; 95% CI: 1.01, 1.55; P = .04). No evidence of significant interactions was found between RVEF and primary or secondary prevention (HR, 1.11 ± 0.17 [standard deviation]; P = .49), ischemic heart disease (HR, 1.02 ± 0.15; P = .78), and LVEF (HR, 0.91 ± 0.8; P = .29). Conclusion Right ventricular ejection fraction measured with cardiac MRI was a predictor of appropriate implantable cardioverter-defibrillator shock or death. © RSNA, 2021 See also the editorial by Nazarian and Zghaib in this issue.

2021 Update on Safety of Magnetic Resonance Imaging: Joint Statement From Canadian Cardiovascular Society/Canadian Society for Cardiovascular Magnetic Resonance/Canadian Heart Rhythm Society

Magnetic resonance imaging (MRI) is often considered the gold-standard test for characterizing cardiac as well as noncardiac structure and function. However, many patients with cardiac implantable electronic devices (CIEDs) and/or severe renal dysfunction are unable to undergo this test because of safety concerns. In the past 10 years, newer-generation CIEDs and gadolinium-based contrast agents (GBCAs) as well as coordinated care between imaging and heart rhythm device teams have mitigated risk to patients and improved access to MRI at many hospitals. The purpose of this statement is to review published data on safety of MRI in patients with conditional and nonconditional CIEDs in addition to patient risks from older and newer GBCAs. This statement was developed through multidisciplinary collaboration of pan-Canadian experts after a relevant and independent literature search by the Canadian Agency for Drugs and Technologies in Health. All recommendations align with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. Key recommendations include: (1) the development of standardized protocols for patients with a CIED undergoing MRI; (2) patients with MRI nonconditional pacemakers and pacemaker dependency should be programmed to asynchronous mode and those with MRI nonconditional transvenous defibrillators should have tachycardia therapies turned off during the scan; and (3) macrocyclic or newer linear GBCAs should be used in preference to older GBCAs because of their better safety profile in patients at higher risk of nephrogenic systemic fibrosis.

Appropriate utilization of cardiac computed tomography for the assessment of stable coronary artery disease

Background

Appropriate use criteria (AUC) have been developed in response to growth in cardiac imaging utilization and concern regarding associated costs. Cardiac computed tomography angiography (CCTA) has emerged as an important modality in the evaluation of coronary artery disease, however its appropriate utilization in actual practice is uncertain. Our objective was to determine the appropriate utilization of CCTA in a large quaternary care institution and to compare appropriate utilization pre and post publication of the 2013 AUC guidelines. We hypothesized that the proportion of appropriate CCTA utilization will be similar to those of other comparable cardiac imaging modalities and that there would be a significant increase in appropriate use post AUC publication.

Methods

We employed a retrospective cohort study design of 2577 consecutive patients undergoing CCTA between January 1, 2012 and December 30, 2016. An appropriateness category was assigned for each CCTA. Appropriateness classifications were compared pre- and post- AUC publication via the chi-square test.

Results

Overall, 83.5% of CCTAs were deemed to be appropriate based on the AUC. Before the AUC publication, 75.0% of CCTAs were classified as appropriate whereas after the AUC publication, 88.0% were classified as appropriate (p < 0.001). The increase in appropriate utilization, when extrapolated to the Medicare population of the United States, was associated with potential cost savings of approximately $57 million per year.

Conclusions

We report a high rate of appropriate use of CCTA and a significant increase in the proportion of CCTAs classified as appropriate after the AUC publication.

Technical Note: Fully automatic segmental relaxometry (FASTR) for cardiac magnetic resonance T1 mapping

PURPOSE

Cardiac relaxometry techniques, particularly T1 mapping, have recently gained clinical importance in various cardiac pathologies. Myocardial T1 and extracellular volume are usually calculated from manual identification of left ventricular epicardial and endocardial regions. This is a laborious process, particularly for large volume studies. Here we present a fully automated relaxometry framework (FASTR) for segmental analysis of T1 maps (both native and postcontrast) and partition coefficient (λ).

METHODS

Patients (N = 11) were imaged postacute myocardial infarction on a 1.5T clinical scanner. The scan protocol involved CINE-SSFP imaging, native, and post-contrast T1 mapping using the Modified Look-Locker Inversion (MOLLI) recovery sequence. FASTR consisted of automatic myocardial segmentation of spatio-temporally coregistered CINE images as an initial guess, followed by refinement of the contours on the T1 maps to derive segmental T1 and λ. T1 and λ were then compared to those obtained from two trained expert observers.

RESULTS

Robust endocardial and epicardial contours were achieved on T1 maps despite the presence of infarcted tissue. Relative to experts, FASTR resulted in myocardial Dice coefficients (native T1: 0.752 ± 0.041; postcontrast T1: 0.751 ± 0.057) that were comparable to interobserver Dice (native T1: 0.803 ± 0.045; postcontrast T1: 0.799 ± 0.054). There were strong correlations observed for T1 and λ derived from experts and FASTR (native T1: r = 0.83; postcontrast T1: r = 0.87; λ: r = 0.78; P < 0.0001), which were comparable to inter-expert correlation coefficients (native T1: r = 0.90; postcontrast T1: r = 0.93; λ: r = 0.80; P < 0.0001).

CONCLUSIONS

Our fully automated framework, FASTR, can generate accurate myocardial segmentations for native and postcontrast MOLLI T1 analysis without the need for manual intervention. Such a design is appealing for high volume clinical protocols.

Calibration and discrimination of the Framingham Risk Score and the Pooled Cohort Equations

BACKGROUND

Although accurate risk prediction is essential in guiding treatment decisions in primary prevention of atherosclerotic cardiovascular disease, the accuracy of the Framingham Risk Score (recommended by a Canadian guideline) and the Pooled Cohort Equations (recommended by US guidelines) has not been assessed in a large contemporary Canadian population. Our primary objective was to assess the calibration and discrimination of the Framingham Risk Score and Pooled Cohort Equations in Ontario, Canada.

METHODS

We conducted an observational study involving Ontario residents aged 40 to 79 years, without a history of atherosclerotic cardiovascular disease, who underwent cholesterol testing and blood pressure measurement from Jan. 1, 2010, to Dec. 31, 2014. We compared predicted event rates generated by the Framingham Risk Score and the Pooled Cohort Equations with observed event rates at 5 years using linkages from validated administrative databases.

RESULTS

Our study cohort included 84 617 individuals (mean age 56.3 yr, 56.9% female). Over a maximum follow-up period of 5 years, we observed 2162 (2.6%) events according to the outcome definition of the Framingham Risk Score, and 1224 (1.4%) events according to the outcome definition of the Pooled Cohort Equations. The predicted event rate of 5.78% by the Framingham Risk Score and 3.51% by the Pooled Cohort Equations at 5 years overestimated observed event rates by 101% and 115%, respectively. The degree of overestimation differed by age and ethnicity. The C statistics for the Framingham Risk Score (0.74) and Pooled Cohort Equations (0.73) were similar.

INTERPRETATION

The Framingham Risk Score and Pooled Cohort Equations significantly overpredicted the actual risks of atherosclerotic cardiovascular disease events in a large population from Ontario. Our finding suggests the need for further refinement of cardiovascular disease risk prediction scores to suit the characteristics of a multiethnic Canadian population.

Predictors of cumulative cost for patients with severe aortic stenosis referred for surgical or transcatheter aortic valve replacement: a population-based study in Ontario, Canada

AIMS 

Transcatheter aortic valve replacement (TAVR) as an alternative to surgical aortic valve replacement (SAVR) has transformed severe aortic stenosis (AS) management. Our aim was understand AS cost drivers from referral to 1-year post-procedure.

METHODS AND RESULTS 

We identified patients referred for either TAVR/SAVR between 1 April 2015 and 31 March 2018, with follow-up until 31 March 2019 in Ontario, Canada. We stratified costs into (i) a referral phase, (ii) a procedural phase from the procedure date to 60 days post-procedure, and (iii) post-procedure phase from 61 days to 1 year. Multivariable regression modelling using generalized linear models with a log link gamma distribution was used to identify cost drivers in each phase. The study cohort included 12 086 AS patients; 4832 were referred for TAVR and 7254 were referred for SAVR. The median cost for TAVR was higher than SAVR in the referral ($3593 vs. $2944) and post-procedural ($5938 vs. $3257) phases. In contrast, for the procedural phase, SAVR had a median cost of $29 756 vs. $27 907 for TAVR. Predictors of high cost in the referral phase were longer wait-time, and an urgent in-hospital procedure. In the procedural phase, procedural complications were the major drivers of higher cost. In the post-procedural phase, patient co-morbidities were the major drivers, specifically dialysis, liver disease, cancer, peripheral vascular disease, and diabetes mellitus.

CONCLUSION 

We identified distinct patterns of cost accumulation and modifiable drivers for SAVR compared with TAVR; these drivers may guide clinical and health policy decisions to make AS care more efficient.

Multi-contrast volumetric imaging with isotropic resolution for assessing infarct heterogeneity: Initial clinical experience

BACKGROUND

To evaluate accelerated multi-contrast volumetric imaging with isotropic resolution reconstructed using low-rank and spatially varying edge-preserving constrained compressed sensing parallel imaging reconstruction (CP-LASER), for assessing infarct heterogeneity on post-infarction patients as a precursor to studies of utility for predicting ventricular arrhythmias.

METHODS

Eleven patients with prior myocardial infarction were included in the study. All subjects underwent cardiovascular magnetic resonance (CMR) scans including conventional two-dimensional late gadolinium enhancement (2D LGE) and three-dimensional multi-contrast late enhancement (3D MCLE) post-contrast. The extent of the infarct core and peri-infarct gray zone of a limited mid-ventricular slab were derived respectively by analyzing MCLE images with an isotropic resolution of 2.2 mm and an anisotropic resolution of 2.2×2.2×8.8 mm 3 , and LGE images with a resolution of 1.37×2.7×8 mm 3 ; the respective measures across all subjects were statistically compared.

RESULTS

Using 3D MCLE, the infarct core size measured with isotropic resolution was similar to that measured with anisotropic resolution, while the peri-infarct gray zone size measured with isotropic resolution was smaller than that measured with anisotropic resolution ( p<0.001 , Cohen's dz=1.33 ). Isotropic 3D MCLE yielded a significantly smaller measure of the peri-infarct gray zone size than conventional 2D LGE ( p=0.0016 , Cohen's dz=1.20 ). Overall, we have successfully shown the utility of isotropic 3D MCLE in a pilot patient study. Our results suggest that smaller voxels lead to more accurate differentiation between isotropic 3D MCLE-derived gray zone and core infarct because of diminished partial volume effect.

CONCLUSION

The CP-LASER accelerated 3D MCLE with isotropic resolution can be used in patients and yields excellent delineation of infarct and peri-infarct gray zone characteristics.

Cine and late gadolinium enhancement MRI registration and automated myocardial infarct heterogeneity quantification

PURPOSE

To develop an approach for automated quantification of myocardial infarct heterogeneity in late gadolinium enhancement (LGE) cardiac MRI.

METHODS

We acquired 2D short-axis cine and 3D LGE in 10 pigs with myocardial infarct. The 2D cine myocardium was segmented and registered to the LGE images. LGE image signal intensities within the warped cine myocardium masks were analyzed to determine the thresholds of infarct core (IC) and gray zone (GZ) for the standard-deviation (SD) and full-width-at-halfmaximum (FWHM) methods. The initial IC, GZ, and IC + GZ segmentations were postprocessed using a normalized cut approach. Cine segmentation and cine-LGE registration accuracies were evaluated using dice similarity coefficient and average symmetric surface distance. Automated IC, GZ, and IC + GZ volumes were compared with manual results using Pearson correlation coefficient (r), Bland-Altman analyses, and intraclass correlation coefficient.

RESULTS

For n = 87 slices containing scar, we achieved cine segmentation dice similarity coefficient = 0.87 ± 0.12, average symmetric surface distance = 0.94 ± 0.74 mm (epicardium), and 1.03 ± 0.82 mm (endocardium) in the scar region. For cine-LGE registration, dice similarity coefficient was 0.90 ± 0.06 and average symmetric surface distance was 0.72 ± 0.39 mm (epicardium) and 0.86 ± 0.53 mm (endocardium) in the scar region. For both SD and FWHM methods, automated IC, GZ, and IC + GZ volumes were strongly (r > 0.70) correlated with manual measurements, and the correlations were not significantly different from interobserver correlations (P > .05). The agreement between automated and manual scar volumes (intraclass correlation coefficient = 0.85-0.96) was similar to that between two observers (intraclass correlation coefficient = 0.81-0.99); automated scar segmentation errors were not significantly different from interobserver segmentation differences (P > .05).

CONCLUSIONS

Our approach provides fully automated cine-LGE MRI registration and LGE myocardial infarct heterogeneity quantification in preclinical studies.

Use of Cardiac Noninvasive Testing After Emergency Department Discharge: Association of Hospital Network Testing Intensity and Outcomes in Ontario, Canada

Background

The relationship between noninvasive cardiac diagnostic testing intensity and downstream clinical outcomes is unclear. Our objective was to examine the relationship between hospital network noninvasive cardiac diagnostic testing intensity and downstream clinical outcomes in patients who were discharged from the emergency department after assessment for chest pain.

Methods and Results

We employed a retrospective cohort study design of 387 809 patients evaluated for chest pain in the emergency department between April 1, 2010 and March 31, 2016. Hospital networks were divided into tertiles based on usage of noninvasive cardiac diagnostic testing. The primary outcome was a composite of acute myocardial infarction or all‐cause mortality. Adjusted Cox proportional hazards models were used to compare the hazard of the composite outcome of myocardical infarction and/or all‐cause mortality between the tertiles. After adjustment for clinically relevant covariates, patients evaluated for chest pain in intermediate noninvasive cardiac diagnostic testing usage tertile hospital networks did not have significantly different hazards of the composite outcome when compared with those evaluated in low usage tertile hospital networks >90 days (hazard ratio [HR], 1.00; 95% CI, 0.83–1.21), 6 months (HR, 1.07; 95% CI, 0.92–1.24), and 1 year (HR, 1.03; 95% CI, 0.94–1.14). Patients evaluated in the high usage tertile also did not have significantly different hazards of the composite outcome compared with those evaluated in the low usage tertile at 90 days (HR, 0.98; 95% CI, 0.80–1.19), 6 months (HR, 1.01; 95% CI, 0.87–1.17); and 1 year (HR, 0.95; 95% CI, 0.86–1.05).

Conclusions

Our population‐based study demonstrated that high noninvasive cardiac diagnostic testing use intensity was not associated with reductions in downstream myocardial infarction or all‐cause mortality.

Cardiac computed tomography and magnetic resonance imaging vs. transoesophageal echocardiography for diagnosing left atrial appendage thrombi

Aims

Transoesophageal echocardiography (TOE) is the gold standard for identification of left atrial appendage (LAA) thrombi. However, TOE is semi-invasive and cannot be performed in certain patients. Left atrial appendage thrombi can also be identified by cardiac computed tomography (CCT) and cardiac magnetic resonance imaging (CMR); however, the diagnostic performance of these techniques vs. TOE is unclear.

Methods and results

We performed a systematic review and meta-analysis of 22 CCT and 4 CMR studies comparing diagnostic performance to TOE for identification of LAA thrombi. Meta-regression was performed to determine whether expected sensitivity and specificity differed between early and delayed image acquisition protocols for CCT vs. TOE and between CCT and CMR. Cardiac computed tomography demonstrated sensitivity and specificity of 0.99 [confidence interval (CI 0.93-1.00)] and 0.94 (CI 0.90-0.97) respectively vs. TOE. A subgroup analysis comparing early vs. delayed protocol CCT imaging was performed showing no significant differences in sensitivity (P-value = 0.17) however improved specificity of the delayed imaging protocols (P-value = 0.04). Cardiac magnetic resonance imaging demonstrated sensitivity and specificity of 0.80 (CI 0.63-0.91) and 0.98 (CI 0.97-0.99), respectively when compared to TOE. There was no significant difference in sensitivity or specificity between CMR and CCT (P-values 0.996 and 0.484, respectively).

Conclusion

Cardiac computed tomography and CMR had good to excellent sensitivity and specificity vs. TOE. Further, there was no significant difference in the sensitivity and specificity of CCT vs. CMR, suggesting that both modalities can be considered reasonable alternatives to TOE in the identification of LAA thrombi. Cardiac magnetic resonance imaging may be especially beneficial when TOE and CCT cannot be performed.

Novel Combined Clinical and Research Protocol to Reduce Wait Times for Cardiac Magnetic Resonance

Cardiac magnetic resonance (CMR) is the gold-standard diagnostic test to evaluate the heart when it begins to fail, a condition known as heart failure. However, wait times for CMR often exceed nine months, leading to delays in diagnosis and subsequent management of patients. In May 2016, we implemented an intervention at our institution where combined clinical and research CMR scans were performed on a research magnetic resonance imaging (MRI) machine, leading to an approximate 45% reduction in clinical wait times. Extension of our experience to other centres across Canada and beyond can reduce wait times and help bring them in line with local/national targets.

Clinical Effectiveness of Cardiac Noninvasive Diagnostic Testing in Outpatients Evaluated for Stable Coronary Artery Disease

Background

Despite more than 4 million cardiac noninvasive diagnostic tests (NIT) being performed annually for stable coronary artery disease in the United States, it is unclear whether they are associated with downstream improvements in outcomes when compared with no testing. We sought to determine whether NIT was associated with reduced downstream major adverse cardiovascular events when compared with not testing.

Methods and Results

We conducted a population‐based study of ≈1.5 million patients undergoing chest pain evaluation in Ontario, Canada. Patients were categorized into NIT and no‐testing groups. Cause‐specific proportional hazards models were used to compare the rate of major adverse cardiovascular events (composite outcome of unstable angina, acute myocardial infarction or cardiovascular mortality and each constituent) between the 2 groups after adjusting for clinically relevant covariates. The rate of the composite outcome was ≈25% lower for patients undergoing noninvasive testing (hazard ratio [HR], 0.77; 95% CI, 0.75–0.79). The benefits of testing were consistent for all 3 constituents of the composite; unstable angina (HR, 0.87; 95% CI, 0.82–0.93 for the NIT versus the no‐testing group), myocardial infarction (HR, 0.83; 95% CI, 0.79–0.86 for the NIT versus the no‐testing group) and cardiovascular mortality (HR, 0.68; 95% CI, 0.65–0.72 for the NIT versus the no‐testing group).

Conclusions

Our large population‐based study reports an ≈25% reduction in major adverse cardiovascular events that was independently associated with NIT in outpatients being evaluated for stable angina. This study demonstrates the prognostic importance of NIT versus no testing on the health of contemporary populations.

Cardiac Rehabilitation During the COVID-19 Era: Guidance on Implementing Virtual Care

Cardiac rehabilitation programs across Canada have suspended in-person services as a result of large-scale physical distancing recommendations designed to flatten the COVID-19 pandemic curve. Virtual cardiac rehabilitation (VCR) offers an alternate mechanism of care delivery, capable of providing similar patient outcomes and safety profiles compared with centre-based programs. To minimize care gaps, all centres should consider developing and implementing a VCR program. The process of this rapid implementation, however, can be daunting. Centres should initially focus on the collation, utilization, and repurposing of existing resources, equipment, and technology. Once established, programs should then focus on ensuring that quality indicators are met and care processes are protocolized. This should be followed by the development of sustainable VCR solutions to account for care gaps that existed before COVID-19, and to improve cardiac rehabilitation delivery, moving forward. This article reviews the potential challenges and obstacles of this process and aims to provide pragmatic guidance to aid clinicians and administrators during this challenging time.

Guiding Cardiac Care During the COVID-19 Pandemic: How Ethics Shapes Our Health System Response

The COVID-19 pandemic has raised ethical questions for the cardiovascular leader and practitioner. Attention has been redirected from a system that focuses on individual patient benefit toward one that focuses on protecting society as a whole. Challenging resource allocation questions highlight the need for a clearly articulated ethics framework that integrates principled decision making into how different cardiovascular care services are prioritized. A practical application of the principles of harm minimisation, fairness, proportionality, respect, reciprocity, flexibility, and procedural justice is provided, and a model for prioritisation of the restoration of cardiovascular services is outlined. The prioritisation model may be used to determine how and when cardiovascular services should be continued or restored. There should be a focus on an iterative and responsive approach to broader health care system needs, such as other disease groups and local outbreaks.

Trends in cardiovascular care and event rates among First Nations and other people with diabetes in Ontario, Canada, 1996-2015

BACKGROUND

Rates of cardiovascular disease among people with diabetes have declined over the last 20-30 years. To determine whether First Nations people have experienced similar declines, we compared time trends in rates of cardiac event and disease management among First Nations people with diabetes and other people with diabetes in Ontario, Canada.

METHODS

We conducted a retrospective cohort study of patients aged 20 to 105 years with diabetes between 1996 and 2015, using linked health administrative databases. Outcomes compared were the annual incidence of each admission to hospital for myocardial infarction and heart failure, and death owing to ischemic heart disease. Management indicators were coronary revascularization and prescription rates for cardioprotective medications. Overall rates and annual percent changes were compared using Poisson regression.

RESULTS

Incidence rates for all cardiac outcomes decreased over the study period. The greatest relative annual decline among First Nations men and women were observed in ischemic heart disease death (4.4%, 95% confidence interval [CI] 3.0 to 5.9) and heart failure (5.4%, 95% CI 4.5 to 6.4), respectively. Among other men and women, the greatest annual declines were seen in ischemic heart disease death (6.3%, 95% CI 6.1 to 6.5 and 7.3%, 95% CI 7.1 to 7.6, respectively). However, all absolute cardiac event rates were higher among First Nations people (p < 0.001). Coronary artery revascularization procedures and prescriptions for cardioprotective medications increased among First Nations people, while only prescriptions increased among other people.

INTERPRETATION

Over the last 20 years, the incidence of cardiac events has declined among First Nations people with diabetes, but remains higher than other people with diabetes in Ontario. For continued reductions in incidence, future efforts need to recognize First Nations people's unique social and cultural determinants of health.

Clinical Effectiveness of Cardiac Noninvasive Diagnostic Testing in Patients Discharged From the Emergency Department for Chest Pain

Background

More than 4 million cardiac noninvasive diagnostic tests are performed annually in the United States. However, questions remain regarding their effectiveness in improving clinical outcomes. We sought to evaluate whether noninvasive diagnostic tests were associated with lower rates of myocardial infarction or cardiovascular death when compared with no testing.

Methods and Results

We performed a retrospective, population‐based cohort study of adults evaluated for chest pain and discharged home from an emergency department in Ontario, Canada. Propensity score matching was employed to reduce confounding between the testing and nontesting groups. There were 370 863 patients evaluated in our cohort. Rates of the composite outcome were low for both groups after propensity‐score matching (0.29% and 0.78% for the nontesting group at 90 days and 1 year, respectively, and 0.34% and 0.68% for the noninvasive diagnostic test group at 90 days and 1 year respectively). Over 1 year, patients undergoing noninvasive diagnostic testing had a small but statistically significant lower hazard of developing the composite outcome of myocardial infarction or cardiovascular mortality (hazard ratio, 0.87; 95% CI, 0.78–0.96 [P<0.01]), which appears to be driven by the high‐risk subgroup (hazard ratio, 0.75; 95% CI, 0.61–0.92 [P<0.01]).

Conclusions

We report a lower observed rate of the composite outcome of cardiovascular death or myocardial infarction associated with noninvasive diagnostic testing following evaluation for chest pain in the emergency department. This lower rate was driven by the high‐risk subgroup. These results suggest that risk‐based testing should be considered for patients discharged from the emergency department for chest pain.

Comparison of Cardiovascular Risk Factors and Outcomes Among Practicing Physicians vs the General Population in Ontario, Canada

IMPORTANCE

Although cardiovascular disease is the leading cause of death in most developed countries, little is known about current physicians' cardiovascular health and outcomes.

OBJECTIVE

To compare cardiac risk factor burden, health services use, and major cardiovascular event incidence between physicians and the general population.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study used data from practicing physicians and nonphysicians without cardiovascular disease aged 40 to 75 years in Ontario, Canada. Cohorts were assembled beginning January 1, 2008, and were followed up to December 31, 2015. Data analysis was performed between November 2017 and September 2019.

EXPOSURE

Being a practicing physician.

MAIN OUTCOMES AND MEASURES

The primary outcome was 8-year incidence of a major cardiovascular event (ie, cardiovascular death or hospitalization for myocardial infarction, stroke, heart failure, or coronary revascularization). Secondary outcomes included health services used, such as physician assessments and guideline-recommended tests.

RESULTS

The cohort comprised 17 071 physicians (mean [SD] age, 53.3 [8.8] years; 11 963 [70.1%] men) and 5 306 038 nonphysicians (mean [SD] age, 53.7 [9.5] years; 2 556 044 [48.2%] men). Physicians had significantly lower baseline rates of hypertension (16.9% vs 29.6%), diabetes (5.0% vs 11.3%), and smoking (13.1% vs 21.6%), while having better cholesterol profiles (total cholesterol levels >240 mg/dL, 13.3% vs 16.5%; low-density lipoprotein cholesterol >130 mg/dL, 33.2% vs 36.8%); age- and sex-adjusted differences were even larger. Physicians also had lower rates of periodic health examinations (58.9% [95% CI, 57.5%-60.4%] vs 67.9% [95% CI, 67.8%-67.9%]), hyperlipidemia screening (76.3% [95% CI, 74.7%-78.0%] vs 83.8% [95% CI, 83.7%-83.9%]), and diabetes screening (79.0% [95% CI, 77.3%-80.8%] vs 85.3% [95% CI, 85.2%-85.4%]), but higher rates of cardiologist consultations (25.2% [95% CI, 24.2%-26.3%] vs 19.5% [95% CI, 19.4%-19.5%]). The 8-year age- and sex-standardized primary outcome incidence was 4.4 major cardiovascular events per 1000 person-years for physicians and 7.1 major cardiovascular events per 1000 person-years for the general population. After adjusting for age, sex, socioeconomic status, and cardiac risks and comorbidities, physicians had a 22% lower hazard (hazard ratio, 0.78; 95% CI, 0.72-0.85) of experiencing the primary outcome compared with the general population.

CONCLUSIONS AND RELEVANCE

Practicing physicians in Ontario had fewer cardiovascular risk factors, underwent less preventive testing, and were less likely to experience major adverse cardiovascular outcomes than the general population.

Use of the Valve Visualization on Echocardiography Grade Tool Improves Sensitivity and Negative Predictive Value of Transthoracic Echocardiogram for Exclusion of Native Valvular Vegetation

BACKGROUND

Transesophageal echocardiography (TEE) remains the preferred test to rule out infective endocarditis (IE) but is resource intensive and carries risk. Multiple studies report low sensitivity of transthoracic echocardiography (TTE) for detection of IE; however, these studies did not account for TTE quality. We test the validity of a simple valve visualization grading tool to stratify TTEs by quality and determine whether a high-quality TTE may be used to exclude valvular vegetation and forgo the need for TEE.

METHODS

The Valve Visualization on Echocardiography Grade (VEG) tool scores the TTE from 0 to 10 based on leaflet visualization and valve leaflet clarity. The tool was retrospectively applied to 309 sequential patients who underwent both TTE and TEE at an academic teaching hospital between 2011 and 2015. The TEE report was the gold standard for presence or absence of vegetation. Patients with prosthetic valves and pacemaker wires were excluded. Sensitivity of TTE for detecting vegetation was calculated at each VEG score, and the optimal cutoff was identified.

RESULTS

A total of 309 patients were included in the analysis. Among the 216 negative TTEs, 19 (9%) had a positive TEE. The median VEG score was 4. A VEG score cutoff >6 provided optimal sensitivity and was used as the cutoff. Overall, 75 (25%) patients had a VEG score >6, and 234 (75%) had a score ≤6. Sensitivity and negative predictive value for IE were higher in the VEG >6 versus VEG ≤6 group (sensitivity 96% vs 66%, negative predictive value 97.5% vs 90%; P < .05). The false-negative rate was lower (2.5% vs 10%; P = .04) in VEG > 6 versus VEG ≤ 6 groups, respectively.

CONCLUSIONS

Leaflet visualization and valve leaflet clarity are important components in the TTE evaluation of patients with suspected IE. This study demonstrates that the better the valve leaflets are visualized on TTE (as represented in this population by a score >6), the higher the confidence one can have that the TTE will not be falsely negative for vegetation(s) when vegetation(s) are not noted on these TTEs. If validated in future prospective studies, this may reduce the need to perform an invasive TEE in selected patients undergoing evaluation for native valve IE.

Profiling Hospital Performance on the Basis of Readmission After Transcatheter Aortic Valve Replacement in Ontario, Canada

Background

Readmission rates are a widely accepted quality indicator. Our objective was to develop models for calculating case‐mixed adjusted readmission rates after transcatheter aortic valve replacement for the purpose of profiling hospitals.

Methods and Results

In this population‐based study in Ontario, Canada, we identified all transcatheter aortic valve replacement procedures between April 1, 2012, and March 31, 2016. For each hospital, we first calculated 30‐day and 1‐year risk‐standardized (predicted versus expected) readmission rates, using 2‐level hierarchical logistic regression models, including clustering of patients within hospitals. We also calculated the risk‐adjusted (observed versus expected) readmission rates, accounting for the competing risk of death using a Fine‐Gray competing risk model. We categorized hospitals into 3 groups: those performing worse than expected, those performing better than expected, or those performing as expected, on the basis of whether the 95% CI was above, below, or included the provincial average readmission rate respectively. Our cohort consisted of 2129 transcatheter aortic valve replacement procedures performed at 10 hospitals. The observed readmission rate was 15.4% at 30 days and 44.2% at 1 year, with a range of 10.9% to 21.7% and 38.8% to 55.0%, respectively, across hospitals. Incorporating the competing risk of death translated into meaningful different results between models; as such, we concluded that the risk‐adjusted readmission rate was the preferred metric. On the basis of the 30‐day risk‐adjusted readmission rate, all hospitals performed as expected, with a 95% CI that included the provincial average. However, we found that there was significant variation in 1‐year risk‐adjusted readmission rate.

Conclusions

There is significant interhospital variation in 1‐year adjusted readmission rates among hospitals, suggesting that this should be a focus for quality improvement efforts in transcatheter aortic valve replacement.

Variation in Revascularization Practice and Outcomes in Asymptomatic Stable Ischemic Heart Disease

OBJECTIVES

The aims of this study were to assess variation in revascularization of asymptomatic patients with stable ischemic heart disease, identify the predictors of variation, and determine if it was associated with clinical outcomes.

BACKGROUND

Management of stable ischemic heart disease in asymptomatic patients with obstructive coronary artery disease is controversial, potentially leading to practice variation.

METHODS

A retrospective observational cohort study was performed using population-based data from Ontario, Canada, in patients with asymptomatic stable ischemic heart disease and obstructive coronary artery disease. The cohort was divided on the basis of treatment strategy: revascularization or medical therapy. Hospitals were allocated into tertiles of their revascularization ratio. Outcomes included death and nonfatal myocardial infarction. Hierarchical logistic regression was used to assess the predictors of revascularization, with median odds ratios used to quantify variation. Proportional hazards models were used to determine the association between management strategy and outcomes.

RESULTS

The cohort included 9,897 patients, 47% treated with medical therapy and 53% with revascularization. Between hospitals, 2-fold variation existed in the ratio of revascularized to medically treated patients. However, the variation across hospitals was not explained by patient, physician, or hospital factors (median odds ratio in null model: 1.25; median odds ratio in full model: 1.31). Revascularization was associated with a hazard ratio of 0.81 (95% confidence interval: 0.69 to 0.96) for death and a hazard ratio of 0.58 (95% confidence interval: 0.46 to 0.73) for myocardial infarction, with this benefit consistent across tertiles of revascularization ratio.

CONCLUSIONS

Wide variation was observed in revascularization practice that was not explained by known factors. Despite this variation, a clinical benefit was observed with revascularization that was consistent across hospitals.

Validation of billing code combinations to identify cardiovascular magnetic resonance imaging scans in Ontario, Canada: a retrospective cohort study

OBJECTIVES

Cardiovascular magnetic resonance (CMR) imaging is the gold-standard test for the assessment of heart function. Despite its importance, many jurisdictions lack specific billing codes that can be used to identify patient receipt of CMR in administrative databases, limiting the ability to perform 'big data' CMR studies. Our objective was to identify the optimal billing code combination to identify patients who underwent CMR using administrative data in Ontario.

DESIGN

Retrospective cohort study.

SETTING

Quaternary care academic referral centre in Ontario, Canada.

PARTICIPANTS

We tested all billing code combinations in order to identify the optimal one to determine receipt of CMR. The reference gold standard was a list of all cardiothoracic magnetic resonance scans performed at Sunnybrook Health Sciences Centre between 1 January 2014 and 31 December 2016, verified by chart audit. We assessed the diagnostic performance (accuracy, sensitivity, specificity, positive predictive value and negative predictive value) for all code combinations.

RESULTS

Our gold-standard cohort consisted of 2339 thoracic MRIs that were performed at Sunnybrook Health Sciences Centre from 1 January 2014 to 31 December 2016. Of these, 2139 (91.5%) were CMRs and 200 (8.5%) were chest MRIs. We identified the most accurate billing combination for the determination of patient receipt of CMR. This combination resulted in an accuracy of 95.3% (95% CI 94.4% to 96.2%), sensitivity of 97.4% (95% CI 96.6% to 98.1%), specificity of 86.4% (95% CI 83.1% to 89.6%), positive predictive value of 96.9% (95% CI 96.1% to 97.6%) and negative predictive value of 88.4% (95% CI 85.4% to 91.5%).

CONCLUSIONS

Our study is the first to verify the ability to accurately identify patient receipt of CMR using administrative data, facilitating more robust population-based CMR studies in the future.

Abstract 165: Temporal Trends in FFR Utilization in Patients Undergoing Coronary Angiography: A Population Based Study

Background: Invasive fractional flow reserve (FFR) has emerged as an important tool to identify a subset of patients in whom coronary revascularization may be beneficial. Our objective was to evaluate temporal trends in FFR utilization.

Methods: In this population-based study, we identified all coronary angiograms in the CorHealth Ontario Cardiac Registry between January 1 st , 2010 to December 31 st , 2015. The primary and secondary outcomes were the age-sex adjusted monthly rate of FFR per 100,000 population and per 100 angiograms respectively. Piecewise regression analysis was used to evaluate the temporal trends in FFR utilization, for the entire cohort, and then stratified by indication (stable coronary disease (SCAD) versus acute coronary syndrome (ACS)).

Results: The study cohort included 379,688 angiograms, of which 122,571 were for SCAD (32%), and 134,769 were for ACS (35%). FFR was performed in 3.2% of all angiograms (4.6% in SCAD; 2.7% in ACS). Monthly age-sex adjusted FFR utilization rates increased significantly over the study period, from 0.4 to 2.1 per 1000,000 people/month. The monthly FFR utilization rate per 100 angiograms increased from 1.3 to 4.8 per 100 angiograms/month; however, the proportion of positive FFR results was relatively constant at 27%. There was a more dramatic increase in the use of FFR in the SCAD (1.4 to 7.5 per 100 angiograms/month) compared to the ACS population (1.3 to 3.4 per 100 angiograms/month).

Conclusions: Over time, there was a 5-fold increase in the use of FFR in patients across Ontario, which was predominantly driven by use in patients with SCAD. Case selection for FFR use was relatively unchanged with approximately a quarter of FFR cases being positive over time.

Appropriate utilization of cardiac magnetic resonance for the assessment of heart failure and potential associated cost savings

BACKGROUND

The rapid growth in cardiac imaging utilization has led to the development of appropriate use criteria (AUC) in an effort to control costs. Recently, cardiac MRI has developed into a valuable modality in the evaluation of cardiac disease. However, there are no studies examining the appropriate use of cardiac MRI in clinical practice.

PURPOSE

To determine the appropriate utilization of cardiac MRI in a large quaternary care institution and to compare percentages of appropriate utilization pre- and postpublication of the AUC document. We hypothesized that percentages of appropriate cardiac MRI utilization will be similar to those of other comparable cardiac imaging modalities and that there would be a significant change in appropriate use pre- and post-AUC publication.

STUDY TYPE

Retrospective cohort study.

POPULATION

In all, 2032 consecutive patients undergoing cardiac MRI for the assessment of heart failure between 2012-2016.

FIELD STRENGTH

1.5T.

ASSESSMENT

Data were collected and an appropriateness category was assigned for each cardiac MRI.

STATISTICAL TESTS

Rates of major cardiac risk factors were compared between those undergoing cardiac MRIs pre- and post-AUC using the chi-square and the Mann-Whitney tests for categorical and continuous variables, respectively. Appropriateness classification was compared pre- and post-AUC publication using the chi-square test.

RESULTS

There were no significant differences in the prevalence of major cardiovascular risk factors before and after publication of the AUC. 95.5% of all cardiac MRIs were appropriate based on the AUC. Further, there was a significant difference when comparing the appropriateness classification before and after publication of the AUC (P = 0.0003), potentially associated with annual cost savings of ∼$14.8 million.

DATA CONCLUSION

We report a very high percentage of appropriate use of cardiac MRI and a significant increase in the proportion of tests classified as appropriate after AUC publication.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2019;49:e132-e138.

The State of Cardiovascular Magnetic Resonance Imaging in Canada: Results from the CanSCMR Pan-Canadian Survey

Over the past 25 years, cardiovascular magnetic resonance imaging (CMR) has developed into an increasingly valuable imaging modality. CMR is now a routine clinical tool for the evaluation of cardiovascular structure and function. However, current patterns in the utilization of CMR in Canada are unknown as are data on important issues such as wait times and appropriate use of this technology. To address these issues, we sought to perform a staged pan-Canadian Survey to initiate dialogue regarding the utilization and appropriate use of CMR in Canada. Two surveys were sent out to participants involved with the performance of CMR at tertiary care referral centres across Canada, one in 2015 and the other in 2017. Questions for both surveys were vetted by the executive committee of the Canadian Society for Cardiovascular Magnetic Resonance and were distributed to sites identified through Canadian Society for Cardiovascular Magnetic Resonance memberships. Descriptive statistics were used to summarize data. Twenty-one sites participated in the 2015 survey and 17 in the 2017 survey. Our results highlighted that most participants believe that CMR is an important component in the clinical decision-making process. They also exposed important issues such as excessive and seemingly worsening wait times for CMR and suggested potential drivers of this phenomenon. Finally, our results confirm ongoing challenges in the imaging community in meeting quality assurance guidelines aimed at documenting appropriate use criteria. Researchers and policy makers should focus on mechanisms aimed to reduce wait times as well as increase use of appropriate use criteria.

Comparison of Anatomic and Clinical Outcomes in Patients Undergoing Alternative Initial Noninvasive Testing Strategies for the Diagnosis of Stable Coronary Artery Disease

Background

The optimal initial noninvasive diagnostic testing strategy for stable coronary artery disease (CAD) is unknown. Although American guidelines recommend an exercise stress test as the first‐line test, European guidelines suggest that stress imaging (myocardial perfusion imaging or stress echocardiography) or coronary computed tomography angiography may be preferable. Understanding the relationship between the initial strategy and downstream yield of obstructive CAD and major adverse cardiac events may provide insight as to the optimal strategy.

Methods and Results

We conducted a population‐based retrospective cohort study of adults in Ontario, Canada, using health administrative and clinical data. The relationship between the initial testing strategy and obstructive CAD on invasive angiography was examined. Patients were then followed from their angiogram onward to determine whether they developed a composite end point of major adverse cardiac events. After adjusting for covariates, patients with initial myocardial perfusion imaging (odds ratio: 0.92; 95% confidence interval, 0.85, 1.00), coronary computed tomography angiography (odds ratio: 1.51; 95% confidence interval, 0.91, 2.49), or stress echo (odds ratio: 0.95; 95% confidence interval, 0.84, 1.08) did not a have significantly different yield of obstructive CAD compared with those with an initial exercise stress test. Furthermore, there was no significant difference in downstream major adverse cardiac events after invasive angiography among the 4 initial testing strategies after adjusting for clinically relevant covariates.

Conclusions

Our study found no evidence to suggest significant differences in either yield of obstructive CAD or downstream major adverse cardiac events in patients undergoing an initial noninvasive testing strategy with stress or anatomical imaging compared with those undergoing an initial exercise stress test.

Impact of the Publication of Appropriate Use Criteria on Utilization Rates of Myocardial Perfusion Imaging Studies in Ontario, Canada: A Population-Based Study

BACKGROUND

Concern regarding overutilization of cardiac imaging has led to the development of appropriate use criteria (AUC). Myocardial perfusion imaging (MPI) is one of the most commonly used cardiac imaging modalities worldwide. Despite multiple iterations of AUC, there is currently no evidence regarding their real-world impact on population-based utilization rates of MPI. Our goal was to assess the impact of the AUC on rates of MPI in Ontario, Canada. We hypothesized that publication of the AUC would be associated with a significant reduction in MPI rates.

METHODS AND RESULTS

We conducted a retrospective cohort study of the adult population of Ontario from January 1, 2000, to December 31, 2015. Age- and sex-standardized rates were compared from 4 different periods intersected by 3 published iterations of the AUC. Overall, 3 072 611 MPI scans were performed in Ontario during our study period. The mean monthly rate increased from 14.1/10 000 in the period from January 2000 to October 2005 to 18.2/10 000 between November 2005 and June 2009. After this point in time, there was a reduction in rates, falling to a mean monthly rate of 17.1/10 000 between March 2014 and December 2015. Time series analysis revealed that publication of the 2009 AUC was associated with a significant reduction in MPI rates (P<0.001). This translated into ≈88 849 fewer MPI scans at a cost savings of ≈72 million Canadian dollars.

CONCLUSIONS

Our results reflect a potential real-world impact of the 2009 MPI AUC by demonstrating evidence of a significant effect on population-based rates of MPI.