Evolving, innovating, and revolutionary changes in cardiovascular imaging: We've only just begun!

In this review, we highlight the need for innovation and creativity to reinvent the field of nuclear cardiology. Revolutionary ideas brought forth today are needed to create greater value in patient care and highlight the need for more contemporary evidence supporting the use of nuclear cardiology practices. We put forth discussions on the need for disruptive innovation in imaging-guided care that places the imager as a central force in care coordination. Value-based nuclear cardiology is defined as care that is both efficient and effective. Novel testing strategies that defer testing in lower risk patients are examples of the kind of innovation needed in today's healthcare environment. A major focus of current research is the evolution of the importance of ischemia and the prognostic significance of non-obstructive atherosclerotic plaque and coronary microvascular dysfunction. Embracing novel paradigms, such as this, can aid in the development of optimal strategies for coronary disease management. We hope that our article will spurn the field toward greater innovation and focus on transformative imaging leading the way for new generations of novel cardiovascular care.

Independent prognostic value of left ventricular contractile reserve and chronotropic response in patients with reduced left ventricular ejection fraction undergoing vasodilator stress myocardial perfusion imaging with Rb-82 positron emission tomography

Objectives

We evaluated the prognostic value of heart rate reserve (ΔHR) and left ventricular ejection fraction reserve (ΔLVEF) among patients with systolic dysfunction.

Background

Inadequate ΔHR (maximal stress HR - resting HR) and ΔLVEF (LVEF at stress - LVEF at rest) in response to stress are associated with adverse cardiac events. However, the significance of an abnormal ΔHR and ΔLVEF in patients with systolic dysfunction has not been described.

Methods and results

We performed a retrospective analysis of patients with rest LVEF < 45% who underwent dipyridamole stress-rest gated Rb-82 PET myocardial perfusion imaging (PET-MPI) at the Cleveland Clinic between 2006 and 2009. Stress LVEF and volumes were calculated using commercially available software (4DM). A Cox proportional hazards model (CPH) was used to examine the association between ΔLVEF, ΔHR, and all-cause death (ACD). Among 461 patients (mean age 65.7 ± 11.3 years, 82% men) 167 experienced ACD (median follow-up 1045 days). Survival was reduced among patients with ΔHR < 0 (1090 vs. 1300 days, P = 0.04) and ΔLVEF < 0 (1002 vs. 1057 days, P = 0.03). In a CPH after adjusting for confounding variables, ΔHR ≤ 0 and ΔLVEF ≤ 0 were associated with reduced survival (hazard ratio 0.93, P < 0.01 and 0.84, P = 0.01, respectively) with an interaction between age and ΔHR (χ2 = 8.1, P < 0.01). Our model predicts that the magnitude of ΔHR is associated with improved survival among younger patients. For any given ΔLVEF the magnitude of ΔHR has a greater positive effect on survival among younger patients.

Conclusion

Both ΔHR and ΔLVEF during pharmacologic stress PET-MPI provide incremental value in predicting ACD among patients with systolic dysfunction.

Ascending Aortic Dimensions in Former National Football League Athletes

BACKGROUND

Ascending aortic dimensions are slightly larger in young competitive athletes compared with sedentary controls, but rarely >40 mm. Whether this finding translates to aortic enlargement in older, former athletes is unknown.

METHODS AND RESULTS

This cross-sectional study involved a sample of 206 former National Football League (NFL) athletes compared with 759 male subjects from the DHS-2 (Dallas Heart Study-2; mean age of 57.1 and 53.6 years, respectively, P<0.0001; body surface area of 2.4 and 2.1 m², respectively, P<0.0001). Midascending aortic dimensions were obtained from computed tomographic scans performed as part of a NFL screening protocol or as part of the DHS. Compared with a population-based control group, former NFL athletes had significantly larger ascending aortic diameters (38±5 versus 34±4 mm; P<0.0001). A significantly higher proportion of former NFL athletes had an aorta of >40 mm (29.6% versus 8.6%; P<0.0001). After adjusting for age, race, body surface area, systolic blood pressure, history of hypertension, current smoking, diabetes mellitus, and lipid profile, the former NFL athletes still had significantly larger ascending aortas (P<0.0001). Former NFL athletes were twice as likely to have an aorta >40 mm after adjusting for the same parameters.

CONCLUSIONS

Ascending aortic dimensions were significantly larger in a sample of former NFL athletes after adjusting for their size, age, race, and cardiac risk factors. Whether this translates to an increased risk is unknown and requires further evaluation.

Discordance between 'actual' and 'scheduled' check-in times at a heart failure clinic

Introduction

A 2015 Institute Of Medicine statement “Transforming Health Care Scheduling and Access: Getting to Now”, has increased concerns regarding patient wait times. Although waiting times have been widely studied, little attention has been paid to the role of patient arrival times as a component of this phenomenon. To this end, we investigated patterns of patient arrival at scheduled ambulatory heart failure (HF) clinic appointments and studied its predictors. We hypothesized that patients are more likely to arrive later than scheduled, with progressively later arrivals later in the day.

Methods and results

Using a business intelligence database we identified 6,194 unique patients that visited the Cleveland Clinic Main Campus HF clinic between January, 2015 and January, 2017. This clinic served both as a tertiary referral center and a community HF clinic. Transplant and left ventricular assist device (LVAD) visits were excluded. Punctuality was defined as the difference between ‘actual’ and ‘scheduled’ check-in times, whereby negative values (i.e., early punctuality) were patients who checked-in early. Contrary to our hypothesis, we found that patients checked-in late only a minority of the time (38% of visits). Additionally, examining punctuality by appointment hour slot we found that patients scheduled after 8AM had progressively earlier check-in times as the day progressed (P < .001 for trend). In both a Random Forest-Regression framework and linear regression models the most important risk-adjusted predictors of early punctuality were: later in the day appointment hour slot, patient having previously been to the hospital, age in the early 70s, and white race.

Conclusions

Patients attending a mixed population ambulatory HF clinic check-in earlier than scheduled times, with progressive discrepant intervals throughout the day. This finding may have significant implications for provider utilization and resource planning in order to maximize clinic efficiency. The impact of elective early arrival on patient’s perceived wait times requires further study.

Regional Variation in Technetium Pyrophosphate Uptake in Transthyretin Cardiac Amyloidosis and Impact on Mortality

OBJECTIVES

This study sought to investigate the regional uptake of technetium 99m-pyrophosphate (TcPYP) in transthyretin cardiac amyloidosis (ATTR) and its association with mortality.

BACKGROUND

TcPYP nuclear scintigraphy is a diagnostic and prognostic tool in ATTR. Echocardiography has identified a pattern of regional variation in longitudinal strain (LS) with a gradient of improved strain from base to apex in ATTR.

METHODS

Consecutive patients with ATTR were evaluated who underwent TcPYP nuclear scintigraphy with planar and attenuation corrected single-photon emission computed tomography (SPECT). Heart-to-contralateral lung (H/CL) ratio was calculated on planar images, and left ventricular (LV) uptake was determined in each of the 17 segments using SPECT. A measure of apical-sparing of myocardial TcPYP uptake, termed the apical-sparing ratio (ASR), was calculated as basal + mid / apical counts.

RESULTS

Overall, 54 patients with ATTR (age 78 ± 9 years, 76% male, 31% hereditary ATTR) were analyzed. There was increased TcPYP uptake in basal and mid relative to apical LV segments, and an apical-sparing LS pattern on echocardiography. The right ventricle similarly showed greater uptake in basal segments. There were 26 deaths over 1.8 years median follow-up. The ASR of TcPYP uptake was associated with age-adjusted all-cause mortality (p = 0.013) with worse prognosis seen at levels <2.75. Global LS was also prognostic (p = 0.01), whereas H/CL ratio and total LV uptake indexed to blood pool were not (p = 0.772 and p = 0.850, respectively). The prognostic utility of the ASR persisted in multivariable modeling (p = 0.003), whereas global LS did not.

CONCLUSIONS

There is decreased TcPYP uptake in apical as compared to mid and basal segments in the LV, mimicking apical-sparing LS seen on echocardiography. Regional distribution of LV TcPYP uptake is associated with mortality, whereas overall amount of uptake as measured by H/CL ratio and indexed LV SPECT uptake is not.

The elusive role of myocardial perfusion imaging in stable ischemic heart disease: Is ISCHEMIA the answer?

The assessment of ischemia through myocardial perfusion imaging (MPI) is widely accepted as an index step in the diagnostic evaluation of stable ischemic heart disease (SIHD). Numerous observational studies have characterized the prognostic significance of ischemia extent and severity. However, the role of ischemia in directing downstream SIHD care including coronary revascularization has remained elusive as reductions in ischemic burden have not translated to improved clinical outcomes in randomized trials. Importantly, selection bias leading to the inclusion of many low risk patients with minimal ischemia have narrowed the generalizability of prior studies along with other limitations. Accordingly, an ongoing randomized controlled trial entitled ISCHEMIA (International Study of Comparative Health Effectiveness with Medical and Invasive Approaches) will compare an invasive coronary revascularization strategy vs a conservative medical therapy approach among stable patients with moderate to severe ischemia. The results of ISCHEMIA may have a substantial impact on the management of SIHD and better define the role of MPI in current SIHD pathways of care.

Prognostic Impact of Extent, Severity, and Heterogeneity of Abnormalities on 18F-FDG PET Scans for Suspected Cardiac Sarcoidosis

OBJECTIVES

This study sought to evaluate the incremental value of quantifying the extent and severity of myocardial perfusion and ¹⁸F-labeled fluorodeoxyglucose (FDG) abnormalities in predicting adverse outcomes among patients with suspicion for cardiac sarcoidosis (CS).

BACKGROUND

Positron emission tomography (PET) with FDG is a key component of the noninvasive assessment of patients with suspected CS. However, the optimal method for image interpretation has not been defined.

METHODS

A retrospective analysis was performed of 203 patients who underwent perfusion and FDG-PET imaging to evaluate for CS. Imaging findings were scored by conventional 3-category methods (normal perfusion and metabolism, abnormal perfusion or metabolism, abnormal perfusion and metabolism) and by summed scores using the 17-segment model to represent extent and severity of disease. Heterogeneity of metabolism was quantified using the coefficient of variation (SD divided by the mean) of FDG uptake. Multivariable Cox models were developed to assess associations between imaging findings and adverse events (death, heart transplant, or ventricular arrhythmia requiring defibrillation).

RESULTS

The indication for FDG-PET was ventricular arrhythmia in 69 (34%), heart block in 16 (8%), cardiomyopathy in 54 (27%), and other indications in 64 (32%). There were 63 patients who developed adverse events over a mean follow-up of 1.8 years. After robust adjustment, only the summed score in segments with a perfusion-metabolism mismatch and the coefficient of variation were important prognostically (p = 0.029 and p = 0.041, respectively).

CONCLUSIONS

Quantitative measures of extent and severity of perfusion-metabolism mismatch and coefficient of variation of FDG uptake provide an incremental prognostic advantage in patients undergoing FDG-PET for CS. These results support the use of a more detailed analysis of imaging findings, as is conventional in coronary artery disease.

Efficacy of Chemotherapy for Light-Chain Amyloidosis in Patients Presenting With Symptomatic Heart Failure

BACKGROUND

Light-chain amyloidosis (AL) with cardiac involvement carries a poor prognosis; median untreated survival is <6 months. Three-drug therapy with bortezomib, dexamethasone, and an alkylating agent (BDex+AA) is associated with improved biomarker response rates in AL amyloidosis.

OBJECTIVES

This study sought to evaluate the effect of BDex+AA as a first-line treatment strategy on mortality in patients with symptomatic heart failure from AL cardiac amyloidosis.

METHODS

Patients newly diagnosed with symptomatic New York Heart Association (NYHA) functional class ≥II heart failure due to AL amyloidosis were retrospectively studied. Initial treatment strategy was adjudicated and propensity score analysis was used to adjust for the nonrandomized allocation of treatments. Survival was assessed using a Cox proportional hazards model after adjusting for the propensity score for receiving treatment, age, NYHA functional class, and ejection fraction.

RESULTS

Among 106 treated patients (age 64.6 ± 11.3 years, 63% male, 76% lambda subtype), 40 received the 3-drug regimen and 66 received other regimens. Mortality was 65% overall, 48% in the BDex+AA cohort (median survival time 821 days), and 76% in patients who received other regimens (median survival time 223 days). Initial treatment with BDex+AA was associated with decreased mortality after multivariable adjustment (hazard ratio: 0.209; 95% confidence interval: 0.069 to 0.636; p = 0.006). This association remained after further adjustment for components of the Mayo Stage.

CONCLUSIONS

Use of BDex+AA in the treatment of AL amyloidosis in patients presenting with symptomatic heart failure is associated with improved survival after adjusting for clinical variables.

Update on Treatment in Cardiac Sarcoidosis

OPINION STATEMENT

The prevalence of cardiac sarcoidosis has exponentially increased over the past decade, primarily due to increased awareness and diagnostic modalities for the disease entity. Despite an expanding patient cohort, the optimal management of cardiac sarcoidosis remains yet to be established with a significant lack of prospective trials to support current practice. Corticosteroids remain first-line treatment of this disorder, and we recommend that immunosuppressive therapy should be initiated in all patients diagnosed with cardiac sarcoidosis. Additional pharmacotherapy may be necessary based on disease manifestations and response to treatment. The use of nuclear imaging with ¹⁸fluorodeoxyglucose (¹⁸FDG) positron emission tomography (PET) to guide treatment has become more common, but lacks rigorous data from larger cohorts. Whether an improvement in inflammatory burden as assessed by ¹⁸FDG-PET is correlated with clinical outcomes is as yet unproven. Device therapy with implantable-cardioverter defibrillators should be considered in all cardiac sarcoidosis patients for either primary or secondary prevention of ventricular arrhythmias and cardiac death.

Prognostic Role of Serum Chloride Levels in Acute Decompensated Heart Failure

BACKGROUND

Acute decompensated heart failure (ADHF) can be complicated by electrolyte abnormalities, but the major focus has been concentrated on the clinical significance of serum sodium levels.

OBJECTIVES

This study sought to determine the prognostic significance of serum chloride levels in relation to serum sodium levels in patients with ADHF.

METHODS

We reviewed 1,318 consecutive patients with chronic heart failure admitted for ADHF to the Cleveland Clinic between July 2008 and December 2013. We also validated our findings in an independent ADHF cohort from the University of Pennsylvania (n = 876).

RESULTS

Admission serum chloride levels during hospitalization for ADHF were independently and inversely associated with long-term mortality (hazard ratio [HR] per unit change: 0.94; 95% confidence interval [CI]: 0.92 to 0.95; p < 0.001). After multivariable risk adjustment, admission chloride levels remained independently associated with mortality (HR per unit change: 0.93; 95% CI: 0.90 to 0.97; p < 0.001) in contrast to admission sodium levels, which were no longer significant (p > 0.05). Results were similar in the validation cohort in unadjusted (HR per unit change for mortality risk within 1 year: 0.93; 95% CI: 0.91 to 0.95; p < 0.001) and multivariable risk-adjusted analysis (HR per unit change for mortality risk within 1 year: 0.95; 95% CI: 0.92 to 0.99; p = 0.01).

CONCLUSIONS

These observations in a contemporary advanced ADHF cohort suggest that serum chloride levels at admission are independently and inversely associated with mortality. The prognostic value of serum sodium in ADHF was diminished compared with chloride.

Assessing Level of Agreement for Atherosclerotic Cardiovascular Disease Risk Categorization Between Coronary Artery Calcium Score and the American College of Cardiology/American Heart Association Cardiovascular Prevention Guidelines and the Potential Impact on Treatment Recommendations

The 2013 American College of Cardiology/American Heart Association cardiovascular prevention guidelines use a new pooled cohort equation (PCE) to predict 10-year risk of atherosclerotic cardiovascular disease (ASCVD) events which form the basis of treatment recommendations. Coronary artery calcium score (CACS) has been proposed as a means to assess atherosclerotic risk. We sought to study the level of agreement in predicted ASCVD risk by CACS and PCE-calculated models and the potential impact on therapy of additional CACS testing. We studied 687 treatment naive, consecutive patients (mean age 53.5 years, 72% men) who had a CACS study at our institution. Clinical and imaging data were recorded. ASCVD risk was calculated using the published PCE-based algorithm. CACS-based risk was categorized by previously published recommendations. Risk stratification comparisons were made and level of agreement calculated. In the cohort, mean ASCVD PCE-calculated risk was 5.3 ± 5.2% and mean CACS was 80 ± 302 Agatston units (AU). Of the intermediate PCE-calculated risk (5% to <7.5%) cohort, 85% had CACS <100 AU. Of the cohort categorized as reasonable to treat per the ASCVD prevention guidelines, 40% had a CACS of 0 AU and an additional 44% had CACS >0 but <100 AU. The level of agreement between the new PCE model of ASCVD risk and demonstrable coronary artery calcium is low. CACS testing may be most beneficial in those with an intermediate risk of ASCVD (PCE-calculated risk of 5% to <7.5%) where, in approximately half of patients, CACS testing significantly refined risk assessment primarily into a very low-risk category.