Heart Rate Variability for Risk Assessment of Myocardial Ischemia in Patients Without Known Coronary Artery Disease: The HRV-DETECT (Heart Rate Variability for the Detection of Myocardial Ischemia) Study

Background

Detecting significant coronary artery disease (CAD) in the general population is complex and relies on combined assessment of traditional CAD risk factors and noninvasive testing. We hypothesized that a CAD‐specific heart rate variability (HRV) algorithm can be used to improve detection of subclinical or early ischemia in patients without known CAD.

Methods and Results

Between 2014 and 2018 we prospectively enrolled 1043 patients with low to intermediate pretest probability for CAD who were screened for myocardial ischemia in tertiary medical centers in the United States and Israel. Patients underwent 1‐hour Holter testing, with immediate HRV analysis using the HeartTrends DyDx algorithm, followed by exercise stress echocardiography (n=612) or exercise myocardial perfusion imaging (n=431). The threshold for low HRV was identified using receiver operating characteristic analysis based on sensitivity and specificity. The primary end point was the presence of myocardial ischemia detected by exercise stress echocardiography or exercise myocardial perfusion imaging. The mean age of patients was 61 years and 38% were women. Myocardial ischemia was detected in 66 (6.3%) patients. After adjustment for CAD risk factors and exercise stress testing results, low HRV was independently associated with a significant 2‐fold increased likelihood for myocardial ischemia (odds ratio, 2.00; 95% CI, 1.41–2.89 [P=0.01]). Adding HRV to traditional CAD risk factors significantly improved the pretest probability for myocardial ischemia.

Conclusions

Our data from a large prospective international clinical study show that short‐term HRV testing can be used as a novel digital‐health modality for enhanced risk assessment in low‐ to intermediate‐risk individuals without known CAD.

Clinical Trial Registration

URL: http://www.ClinicalTrials.gov. Unique identifiers: NCT01657006, NCT02201017).

Feasibility study of a novel general purpose CZT-based digital SPECT camera: initial clinical results

Background

The performance of a prototype novel digital single-photon emission computed tomography (SPECT) camera with multiple pixelated CZT detectors and high sensitivity collimators (Digital SPECT; Valiance X12 prototype, Molecular Dynamics) was evaluated in various clinical settings.

Images obtained in the prototype system were compared to images from an analog camera fitted with high-resolution collimators. Clinical feasibility, image quality, and diagnostic performance of the prototype were evaluated in 36 SPECT studies in 35 patients including bone (n = 21), brain (n = 5), lung perfusion (n = 3), and parathyroid (n = 3) and one study each of sentinel node and labeled white blood cells. Images were graded on a scale of 1–4 for sharpness, contrast, overall quality, and diagnostic confidence.

Results

Digital CZT SPECT provided a statistically significant improvement in sharpness and contrast in clinical cases (mean score of 3.79 ± 0.61 vs. 3.26 ± 0.50 and 3.92 ± 0.29 vs. 3.34 ± 0.47 respectively, p < 0.001 for both). Overall image quality was slightly higher for the digital SPECT but not statistically significant (3.74 vs. 3.66).

Conclusion

CZT SPECT provided significantly improved image sharpness and contrast compared to the analog system in the clinical settings evaluated. Further studies will evaluate the diagnostic performance of the system in large patient cohorts in additional clinical settings.

Twenty-four-hour ambulatory electrocardiography in elderly subjects: prevalence of various arrhythmias and prognostic implications (report from the Bronx Longitudinal Aging Study)

Functional, ambulatory, community-dwelling subjects (n = 423, aged 75 to 85 years) underwent baseline 24-hour ambulatory electrocardiography (ECG) examinations as part of the Bronx Aging Study, a 10-year prospective cohort study designed to identify risk factors and disease markers for cardiovascular, cerebrovascular, and dementia illnesses in old people. Premature ventricular contractions were the most commonly observed arrhythmia noted (93% of subjects), with a low prevalence of nonsustained ventricular tachycardia (5%), paroxysmal atrial tachycardia (13%), atrial fibrillation (4%), and atrioventricular blocks (4%). A 24-hour sinus rate of < 60 beats/min was noted in 13% of subjects, and 11% of subjects were noted to have transient episodes of severe bradycardia (< 40 beats/min). In a multivariate analysis, nonsustained ventricular tachycardia was an independent predictor of death (p = 0.015; relative risk [RR] 2.8; 95% confidence interval [CI] 1.4 to 5.8) and myocardial infarction (p = 0.031; RR 3.2; CI 1.2 to 9.4). Transient atrioventricular block was an independent predictor of stroke (p - 0.0006; RR 9.7; CI 3.3 to 28.9), as was sinus bradycardia over a 24-hour period (p = 0.033; RR 2.7; CI 1.2 to 6.4). Ventricular tachycardia approached significance as an independent predictor of multiinfarct dementia (p = 0.052; RR 6.3; CI 1.4 to 28.7). Episodes of paroxysmal atrial fibrillation, a trial tachycardia, and severe bradycardia were not associated with adverse outcomes. Some arrhythmias found on the ambulatory ECG in very old subjects can predict an increased risk for subsequent death, myocardial infarction, stroke, and multiinfarct dementia.

Differences in Mortality of New-Onset (De-Novo) Acute Heart Failure Versus Acute Decompensated Chronic Heart Failure

Minimal attention has been paid to understanding the implications of the chronicity of heart failure (HF) diagnosis on prognosis of hospitalized patients with acute HF (AHF). We aimed to assess the differences in outcomes between hospitalized patients with AHF that are new-onset (de-novo) AHF and acutely decompensated chronic HF (ADCHF). We analyzed data of 2,328 patients with AHF, who were enrolled in the HF survey in Israel. Patients were classified into de-novo AHF and ADCHF. A total of 721 (31%) patients were classified as de-novo AHF and 1,607 (69%) patients were classified as ADCHF. Patients with de-novo AHF were more likely to be younger, with fewer co-morbidities represented by lower Charlson index, and less likely to have past myocardial infarction as well as coronary revascularization. At 30 days mortality rates were similar in both groups (9% vs 8% in de-novo AHF and ADCHF, respectively). Survival analysis showed that at 1 and 10 years the all-cause mortality rates were significantly higher in patients with ADCHF (33% vs 22% and 90% vs 72%, 1 and 10 years, log-rank p < 0.001, respectively). Consistently, multivariable analysis showed that patients with ADCHF had an independently 58% and 48%, higher mortality risk at 1 and 10 years, respectively, (1-year hazard ratio = 1.58; 95% confidence interval 1.05 to 2.38, p = 0.03; 10-year hazard ratio = 1.48; 95% confidence interval = 1.23 to 2.77; p < 0.001). In conclusion, previous history of HF is an independent predictor of 1-year and 10-year mortality after hospitalization for AHF. Distinction between de-novo AHF and ADCHF may improve our understanding and risk stratification of patients with AHF.

The prognostic significance of improvement in exercise capacity in heart failure patients who participate in cardiac rehabilitation programme

Introduction There are limited contemporary data regarding the association between improvement in cardiovascular fitness in heart failure patients who participate in a cardiac rehabilitation programme and the risk of subsequent hospitalisations. Methods The study population comprised 421 patients with heart failure who participated in our cardiac rehabilitation programme between the years 2009 and 2016. All were evaluated by a standard exercise stress test before initiation, and underwent a second exercise stress test on completion of 3 ± 1 months of training. Participants were dichotomised by fitness level at baseline, according to the percentage of predicted age and sex norms achieved. Each group was further divided according to its degree of functional improvement, between the baseline and the follow-up exercise stress test. Major improvement was defined as improvement above the median value in each group. The combined primary endpoint was cardiac hospitalisation or all-cause mortality. Results A total of 211 (50%) patients had low baseline fitness (<73% (median)) for age and sex-predicted metabolic equivalents of task value. Compared to patients with higher fitness, those with a low baseline fitness were more commonly smokers, had diabetes and were obese ( P < 0.05 for all). Multivariable Cox proportional hazard regression analysis showed that, independent of baseline capacity, an improvement of 5% of predicted fitness was associated with a corresponding 10% reduced risk of cardiac hospitalisation or all-cause mortality ( P < 0.001). Conclusion In heart failure patients participating in a cardiac rehabilitation programme, improved cardiovascular fitness is associated with reduced mortality or cardiac hospitalisation risk during long-term follow-up, independent of baseline fitness.

Echocardiographic comparison of left ventricular structure and function in hypertensive patients with primary aldosteronism and essential hypertension

BACKGROUND

In experimental renovascular hypertension, aldosterone has been implicated in myocardial remodeling and fibrosis, but it is uncertain whether excess aldosterone effects left ventricular structure and function in hypertensive patients.

METHODS

Hypertensive patients from the Cardiovascular Center of the New York Presbyterian Hospital-Weill Cornell Medical Center in New York and the Russian Cardiovascular Research Institute, Moscow, Russia, were studied. The sample included 35 patients with primary aldosteronism and 35 controls with essential hypertension matched for age, gender, and blood pressure (BP). Left ventricular (LV) mass, endocardial and midwall fractional shortening, and circumferential end-systolic stress were calculated. The observed/predicted midwall shortening ratio was used as an index of LV performance corrected for afterload.

RESULTS

Primary aldosteronism and essential hypertension patients had comparable LV dimensions, wall thickness, mass, mass/body surface area, and mass/height. Endocardial and midwall fractional shortening, and afterload-corrected midwall shortening were similar in primary aldosteronism and essential hypertension groups from both clinics. Moreover, logistic regression analysis using BP, body mass index, height, gender, and center as covariates failed to identify statistical differences in LV geometry or systolic function between primary aldosteronism and essential hypertension patients.

CONCLUSIONS

Patients with primary aldosteronism, a state characterized by chronic aldosterone excess, had similar LV geometry and systolic function compared to essential hypertension patients matched for age, gender, and BP. This argues against important independent associations between aldosterone and these aspects of LV response to human hypertension.

The addition of vildagliptin to metformin prevents the elevation of interleukin 1ß in patients with type 2 diabetes and coronary artery disease: a prospective, randomized, open-label study

BACKGROUND

Patients with type 2 diabetes present with an accelerated atherosclerotic process. Animal evidence indicates that dipeptidyl peptidase-4 inhibitors (gliptins) have anti-inflammatory and anti-atherosclerotic effects, yet clinical data are scarcely available.

DESIGN AND METHODS

A prospective, randomized, open-label study was performed in 60 patients with coronary artery disease (CAD) and type 2 diabetes, who participated in a cardiac rehabilitation program. After a washout period of 3 weeks, patients were randomized in a 2:1 ratio to receive combined vildagliptin/metformin therapy (intervention group: n = 40) vs. metformin alone (control group: n = 20) for a total of 12 weeks. Blinded assessment of interleukin-1ß (IL-1ß, the primary endpoint), hemoglobin A1c (HbA1c), and high sensitivity C reactive protein (hsCRP), were performed at baseline and after 12 weeks.

RESULTS

Mean age of study patients was 67 ± 9 years, 75% were males, and baseline HbA1c and inflammatory markers levels were similar between the two groups. At 12 weeks of follow up, levels of IL-1ß, hsCRP, and HbA1c were significantly lower in the intervention group as compared with the control group. There was a continuous elevation of IL-1ß among the control group, which was not observed in the intervention group (49 vs. 4%, respectively; p < 0.001). The hsCRP was lowered by 60% in the vildagliptin/metformin group vs. 23% in the metformin group (p < 0.01). Moreover, a significant relative reduction of the HbA1c was seen in the intervention group (7% reduction, p < 0.03).

CONCLUSION

The addition of vildagliptin to metformin treatment in patients with type 2 diabetes and CAD led to a significant suppression of the IL-1ß elevation during follow up. A significant relative reduction of hsCRP and HbA1c in the intervention group was also observed. Trial registration NCT01604213.

Comparison of the usefulness of heart rate variability versus exercise stress testing for the detection of myocardial ischemia in patients without known coronary artery disease

Heart rate variability (HRV) has been shown to be attenuated in patients with coronary artery disease (CAD) and may, therefore, be possibly used for the early detection of myocardial ischemia. We aimed to evaluate the diagnostic yield of a novel short-term HRV algorithm for the detection of myocardial ischemia in subjects without known CAD. We prospectively enrolled 450 subjects without known CAD who were referred to tertiary medical centers for exercise stress testing (EST) with single-photon emission computed tomography myocardial perfusion imaging (MPI). All subjects underwent 1-hour Holter testing with subsequent HRV analysis before EST with MPI. The diagnostic yield of HRV analysis was compared with EST, using MPI as the gold standard for the noninvasive detection of myocardial ischemia. All subjects had intermediate pretest probability for CAD. Mean age was 62 years, 38% were women, 51% had hypertension, and 25% diabetes mellitus. HRV analysis showed superior sensitivity (77%) compared with standard EST (27%). After multivariate adjustment, HRV was independently associated with an 8.4-fold (p <0.001) increased likelihood for the detection of myocardial ischemia by MPI, whereas EST did not show a statistically significant association with a positive MPI (odds ratio 2.1; p = 0.12). Of subjects who were referred for subsequent coronary angiography, the respective sensitivities of HRV and EST for the detection of significant CAD were 73% versus 26%. Our data suggest that HRV can be used as an important noninvasive technique for the detection of myocardial ischemia in subjects without known CAD, providing superior sensitivity to conventional EST in this population.

Endothelial function predicts 1-year adverse clinical outcome in patients hospitalized in the emergency department chest pain unit

BACKGROUND

Endothelial function is a marker for cardiovascular risk. Thus, abnormal endothelial function may be associated with adverse 1-year outcome in patients presenting to the emergency department chest pain unit (CPU).

METHODS

Following endothelial function testing, using EndoPAT 2000 in 300 consecutive subjects with chest pain and no history of coronary artery disease (CAD) presenting to CPU, patients underwent coronary computerized tomographic angiography (CCTA) or single-photon emission computed tomography according to availability.

RESULTS

Mean 10-year Framingham risk score (FRS) was 6.6±5.9%, median reactive hyperemia index (RHI) as a measure of endothelial function 2.08 and mean was 2.0±0.4. During a 1-year follow-up, the 20 (6.6%) patients who developed major adverse cardiovascular end-points (MACE), including all-cause mortality, non-fatal myocardial infarction, hospitalization for heart failure or angina pectoris, stroke, coronary artery bypass grafting and percutaneous coronary interventions, had higher 10-year FRS (10.5±8.2% vs 6.3±5.7%; p<0.001), lower baseline RHI (1.43±0.41 vs 2.10±0.44; p<0.001) and a greater extent of coronary atherosclerosis lesions (70% vs 3.9%, p<0.001) in the CPU CCTA, compared to those without MACE. RHI≤the median was associated with higher 1-year MACE (13% vs 0.7%, p<0.001) compared to RHI>the median. Multivariate analysis demonstrated that RHI≤the median is an independent predictor of coronary atherosclerosis lesions in the CPU CCTA (OR 5.98, 95% CI 03.29-10.88; p<0.001) and 1-year MACE (OR 15.207, 95% CI 2.00-115.33; p<0.01).

CONCLUSIONS

Our findings suggest that non-invasive endothelial function testing may have clinical utility in triaging patients in the CPU and in predicting 1-year MACE.

Impaired Fasting Glucose Is the Major Determinant of the 20-Year Mortality Risk Associated With Metabolic Syndrome in Nondiabetic Patients With Stable Coronary Artery Disease

Background

We wanted to explore the association of metabolic syndrome (MetS) versus its individual components with 20‐year all‐cause mortality among patients with stable coronary artery disease.

Methods and Results

The cohort comprised 12 403 nondiabetic patients with stable coronary artery disease who were enrolled in the Bezafibrate Infarction Prevention Registry between February 1990 and October 1992 and followed up through December 2014. The study cohort was divided into 4 groups: patients without MetS or impaired fasting glucose (IFG), patients with IFG but without MetS, patients with MetS but without IFG, and patients with both MetS and IFG. Kaplan‐Meier survival analysis showed that at 20 years of follow‐up, the rates of all‐cause mortality were the highest among patients with both MetS and IFG (66%). Patients with IFG without MetS experienced a significantly higher mortality rate compared with those with MetS without IFG (61% versus 56%; log‐rank P<0.001). Multivariable Cox proportional hazard analysis showed that the final Cox model demonstrated that the additive effect of MetS (hazard ratio, 1.13; 95% confidence interval, 1.1–1.16; P=0.02) and IFG (hazard ratio, 1.54; 95% confidence interval, 1.46–1.62; P<0.001) on 20 years mortality was nonsignificant (hazard ratio, 1.01; 95% confidence interval, 0.93–1.11; P=0.69). IFG was associated with the most pronounced increase in mortality risk among the individual components (hazard ratio, 1.22; 95% confidence interval, 1.14–1.3; P<0.001).

Conclusions

Our findings suggest that IFG alone is a major independent predictor of long‐term mortality among patients with stable coronary artery disease versus other components of the MetS.

CHADS2 and CHA2DS2-VASc scores as predictors of platelet reactivity in acute coronary syndrome

BACKGROUND

Platelet function testing (PFT) in patients treated with P2Y₁₂ inhibitors has been widely evaluated for the prediction of stent thrombosis, myocardial infarction, and bleeding events following percutaneous coronary intervention (PCI) in acute coronary syndrome (ACS). Thus, PFT-guided treatment could positively affect patient outcomes. Data regarding clinical parameters for predicting platelet reactivity in ACS patients are limited. Therefore, our study aims to evaluate CHADS2 and CHA2DS2-VASc scores as predictors for platelet reactivity in ACS patients.

METHODS

Two hundred and ninety-one consecutive patients who underwent PCI and were treated with aspirin and clopidogrel due to ACS were tested for their CHADS2, CHA2DS2-VASc scores and platelet reactivity using adenosine diphosphate (ADP)-induced aggregation (conventional aggregometry). Patients were classified into groups according to their CHADS2 and CHA2DS2-VASc scores. Low-risk group (0-1 score) for CHADS2 and CHA2DS2-VASc scores and high-risk group (2-6, 2-9) for CHADS2 and CHA2DS2-VASc scores, respectively. Furthermore, platelet reactivity in each group were compared (low CHADS2 group vs high CHADS2 group, and low CHA2DS2-VASc vs high CHA2DS2-VASc). Platelet reactivity was defined as low platelet reactivity (<19 U), optimal platelet reactivity [(OPR); 19-46 U], and high on-treatment platelet reactivity [(HPR); >46 U]. Thereafter receiver operating characteristic curve analysis was conducted to verify whether CHADS2 and CHA2DS2-VASc scores could predict platelet reactivity.

RESULTS

Low CHADS2 and CHA2DS2-VASc scores were significantly correlated with lower mean platelet ADP-induced aggregation as compared with high CHADS2 and CHA2DS2-VASc scores [45.5 U (± 16) vs. 54.8 U (±15) and 44.2 U (±16) vs. 51.0 U (±17), respectively, p = 0.01 for both].

CONCLUSION

In ACS patients treated with clopidogrel following PCI, high CHADS2 and CHA2DS2-VASc scores correlated with HPR and lower scores correlated with OPR. Further studies are needed to evaluate our findings' clinical implications.

A new cardiac phantom for dynamic SPECT

BACKGROUND

In recent years, with the advance of myocardial blood flow (MBF) measurement capability in dynamic single photon emission computerized tomography (SPECT) systems, significant effort has been devoted to validation of the new capability. Unfortunately, the mechanical phantoms available for the validation process lack essential features-they either have a constant radiotracer concentration or they have rigid (static) walls unable to simulate cardiac beating.

METHODS AND RESULTS

We have developed a mechanical cardiac phantom that is able to mimic physiological radiotracer variation in the left ventricle (LV) cavity and in the myocardium (M), while performing beating-like motion. We have also developed a mathematical model of the phantom, allowing a description of the radiotracer concentrations in both regions (LV, M) as a function of time, which served as a tool for experiment planning and to accurately mimic physiological-like time-activity curves (TACs). A net retention model for the phantom was also developed, which served to compute the theoretical (i.e., expected) MBF of the phantom from measured quantities only, and thus validate the MBF reported by the SPECT system. In this paper, phantom experiments were performed on a GE Discovery NM 530c SPECT system.

CONCLUSIONS

A novel dynamic cardiac phantom for emission tomography has been developed. The new phantom is capable of producing a wide range of TACs that can mimic physiological (and potentially in the future, pathological) curves, similar to those observed in dynamic SPECT systems. SPECT-reported MBF values were validated against known (measured) activity of the injected radiotracer from phantom experiments, which allowed to determine the accuracy of the GE Discovery 530c SPECT system.

Sex differences of patients with acute chest pain evaluated through a chest pain unit

BACKGROUND

Although sex disparities between patients with acute myocardial infarction are well known, the data regarding sex differences among symptomatic patients with acute chest pain (ACP) are limited.

METHODS

We retrospectively evaluated the records of 1000 consecutive patients with ACP and hospitalized in a tertiary medical center chest pain unit (CPU). Patients were divided according to sex. The primary outcome was defined as a composite end point of readmission because of chest pain, incidence of acute coronary syndrome, revascularization, and death at 90 days and 1 year.

RESULTS

Overall, 673 men and 327 women were included in the current analysis. There was no difference in regard to sex for patients who underwent noninvasive evaluation, (87.8 vs. 87.3%, P = 0.85, for female vs. male, respectively). Among patients who underwent coronary computed tomography angiography, women were less likely to have significant coronary artery disease (CAD) (4.2 vs. 11.3%, P = 0.005). Similarly, women had fewer significant findings (4.4 vs. 7.6%, P = 0.007) on myocardial perfusion imaging. Consequently, fewer women underwent angiography (8 vs. 14%, P = 0.006) and revascularization (2.8 vs. 7.3%, P = 0.004). During follow-up, sex was not associated with the development of the primary composite outcome [odds ratio (OR) 0.91, 95% confidence interval (CI) 0.39-2.09, P-value = 0.82 and OR 1.16, 95% CI 0.65-2.06, P-value = 0.59 for 90-day and 1-year follow-up, respectively].

CONCLUSION

Evaluation of patients through a CPU enables comparable noninvasive evaluation, appropriate utilization of invasive assessment with similar outcomes during the short and intermediate follow-up period regardless of patients' sex.

Early post-stress decrease in cardiac performance by impedance cardiography and its relationship to the severity and extent of ischemia by myocardial perfusion imaging

Background

While single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is a well-established noninvasive procedure for the evaluation of patients with coronary artery disease (CAD), it is unable to detect the presence of, or underestimates the extent of CAD in certain patients. We aimed to show that a bio-impedance device can detect early post-stress changes in several hemodynamic parameters, thereby serving as a potential marker for the presence of significant ischemia.

Methods

Prospectively enrolled patients, referred to our Medical Center for clinically-indicated MPI, underwent testing using a Non-Invasive Cardiac System (NICaS) before and immediately after exercise. The differences between rest and stress hemodynamic parameters were compared with the severity and extent of myocardial ischemia by MPI. The study included 198 patients; mean age was 62 years, 26% were women, 54% had hypertension, and 29% diabetes mellitus. Of them, 188 patients had ≤10%, and 10 had > 10% of myocardial ischemia.

Results

In the first group, there was a significantly greater increase in post-exercise stroke index, stroke work index, cardiac index and cardiac power index (19.2, 29.1, 90.5 and 107%, respectively) compared with the second group (− 2.7, 3.8, 43.7 and 53.5%, respectively), as well as a significantly greater decrease in total peripheral resistance index (− 38.7% compared with − 16.3%), with corresponding p values of 0.015, 0.017, 0.040, 0.016, and < 0.001, respectively.

Conclusions

Our data suggest that immediate post-stress changes in several hemodynamic parameters, detected by the NICaS, can be used as an important adjunct to SPECT MPI for the early detection of myocardial ischemia.

Poor outcome among patients undergoing myocardial perfusion imaging with intermediate-zone troponin

BACKGROUND

Intermediate zone troponin elevation is defined as one to five times the upper limit of normal. Approximately half the patients presenting with chest pain to the emergency department have initial intermediate zone troponin.

OBJECTIVES

We aimed to investigate the long-term outcome of patients hospitalized with chest pain and intermediate zone troponin elevation.

METHODS

We investigated 8269 patients hospitalized in a tertiary center with chest pain. All patients had serial measurements of troponin during hospitalization. Patients were divided into three groups based on their initial troponin levels: negative troponin (N = 6112), intermediate zone troponin (N = 1329) and positive troponin (N = 828). All patients underwent myocardial perfusion imaging (MPI) as part of the initial evaluation.

RESULTS

Mean age of the study population was 68 ± 11, of whom 36% were women. Patients with an intermediate zone troponin were older, more likely to be males, and with significantly more cardiovascular co-morbidities. Multivariate analysis adjusted for age, gender, cardiovascular risk factors, and abnormal MPI result found that patients with intermediate zone troponin had a 70% increased risk of re-hospitalization at 1 year (HR 1.70, 95%CI 1.48-1.96, p-value < 0.001) and 5.3 times higher risk of total mortality at 1-year (HR 5.33, 95%CI 3.65-7.78, p-value < 0.001). sub-group analysis found that among the intermediate zone troponin group, patients with double intermediate zone troponin had the poorest outcome.

CONCLUSIONS

Intermediate zone troponin elevation is an independent risk factor associated with adverse outcomes and therefore patients with an initial value in this range should be closely monitored and aggressively managed.

Dose-consistent dynamic SPECT

BACKGROUND

Coronary flow reserve (CFR) values measured by dynamic SPECT systems are typically consistent with other modalities (e.g., PET). However, large discrepancies are often observed for individual patients. Positioning of the region-of-interest (ROI), representing the arterial input function (AIF) could explain some of these discrepancies. We explored the possibility of positioning the ROI in a manner that evaluates its consistency with patient-based injected radiotracer doses.

METHODS

Dose-consistent dynamic SPECT methodology was introduced, and its application was demonstrated in a twenty-patient clinical study. The effect of various ROI positions was investigated and comparison to myocardial perfusion imaging was performed.

RESULTS

Mean AIF ratios were consistent with the injected dose ratios for all examined ROI positions. Good agreement (> 80%) between total perfusion deficit and CFR was found in the detection of obstructive CAD patients for all ROIs considered. However, for individual patients, significant dependence on ROI position was observed (altering CFR by typically 30%). The proposed methodology's uncertainty was evaluated (~ 7%) and found to be smaller than the variability due to choice of ROI position.

CONCLUSION

Dose-consistent dynamic SPECT may contribute to evaluating uncertainty of CFR measurements and may potentially decrease uncertainty by allowing improved ROI positioning for individual patients.

Pericardial Involvement in ST-Segment Elevation Myocardial Infarction as Detected by Cardiac MRI

Background

Post myocardial infarction pericarditis is considered relatively rare in the current reperfusion era. The true incidence of pericardial involvement may be underestimated since the diagnosis is usually based on clinical and echocardiographic parameters.

Objectives

This study aims to document the incidence, extent, and prognostic implication of pericardial involvement in ST-segment elevation myocardial infarction (PISTEMI) using cardiac MRI (CMR).

Methods

One hundred and eighty-seven consecutive ST-segment elevation myocardial infarction patients underwent CMR on day 5 ± 1 following admission, including steady-state free precession (SSFP) and late Gadolinium enhancement (LGE) sequences. Late Gadolinium enhancement and microvascular obstruction (MVO) were quantified as a percentage of left ventricular (LV) mass. Late Gadolinium enhancement was graded for transmurality according to the 17 AHA left ventricle (LV) segment model (LGE score). Late pericardial enhancement (LPE), the CMR evidence of pericardial involvement, was defined as enhanced pericardium in the LGE series and was retrospectively recorded as present or absent according to the 17 AHA segments. Late pericardial enhancement was evaluated adjacent to the LV, the right ventricle, and both atria. Clinical, laboratory, angiographic, and echocardiographic data were collected. Clinical follow-up for major adverse cardiac events (MACE) was documented and correlated with CMR indices, including LGE, MVO, and LPE.

Results

Late pericardial enhancement (LPE+) was documented in 77.5% of the study cohort. A strong association was found between LPE and the degree and extent of myocardial injury (LGE, MVO). Both LGE and MVO were significantly correlated with increased MACE on follow-up. On the contrary, LPE presence, either adjacent to the LV or the other cardiac chambers, was associated with a lower MACE rate in a median of 3 years of follow-up HR 0.39, 95% CI (0.21–0.7), p = 0.002, and HR 0.48, 95% CI (0.26–0.9), p = 0.02, respectively.

Conclusions

Prognostic implication of pericardial involvement in ST-segment elevation myocardial infarction was documented by CMR in 77.5% of our STEMI cohort. Late pericardial enhancement presence correlated significantly with the extent and severity of the myocardial damage. Unexpectedly, it was associated with a considerably lower MACE rate in the follow-up period.

Validation of advanced hybrid SPECT/CT system using dynamic anthropomorphic cardiac phantom

OBJECTIVE

Myocardial blood flow (MBF) assessment can provide incremental diagnostic and prognostic information and thus the validation of dynamic SPECT is of high importance. We recently developed a novel cardiac phantom for dynamic SPECT validation and compared its performance against the GE Discovery NM 530c. We now report its use for validation of a new hybrid SPECT/CT System featuring advanced cadmium zinc telluride (CZT) technology in a ring array detector design (StarGuide™, GE HealthCare).

METHODS

Our recently developed cardiac phantom with injected technetium-99m radiotracer was used to create physiological time activity curves (TACs) for the left ventricular (LV) cavity and the myocardium. The TACs allow the calculation of uptake rate (K1) and MBF. The StarGuide system was used to acquire and process the TACs, and these were compared to the TACs produced by the phantom and its mathematical model. Fifteen (15) experiments with different doses representing various MBF values were conducted, and a standard statistic tool was applied for significance.

RESULTS

The TACs produced by the StarGuide system had a significant correlation (p < 0.001) with the reference TACs generated by the phantom both for the LV (r = 0.94) and for the myocardium (r = 0.89). The calculated MBF difference between the system and the phantom was 0.14 ± 0.16 ml/min/g and the average relative absolute difference was 13.2 ± 8.1%. A coefficient of variance of ≤ 11% was observed for all MBF subranges. The regional uptake rate values were similar to the global one with a maximum difference of 5%.

CONCLUSIONS

Our newly developed dynamic cardiac phantom was used for validation of the dynamic hybrid SPECT/CT CZT-based system (StarGuide™, GE). The accuracy and precision of the system for assessing MBF values were high. The new StarGuide system can reliably perform dynamic SPECT acquisitions over a wide range of myocardial perfusion flow rates.

Endothelial function predicts 5-year adverse outcome in patients hospitalized in an emergency department chest pain unit

BACKGROUND

Although endothelial function is a marker for cardiovascular risk, endothelial dysfunction assessment is not routinely used in daily clinical practice. A growing challenge has emerged in identifying patients prone to cardiovascular events. We aim to investigate whether abnormal endothelial function may be associated with adverse 5-year outcomes in patients presenting to a chest pain unit (CPU).

METHODS

Following endothelial function testing using EndoPAT 2000 in 300 consecutive patients without a history of coronary artery disease, patients underwent coronary computerized tomographic angiography (CCTA) or single-photon emission computed tomography according to availability.

RESULTS

Mean 10-year Framingham risk score (FRS) was 6.6 ± 5.9%; mean 10-year atherosclerotic cardiovascular disease (ASCVD) risk was 7.1 ± 7.2%; median reactive hyperemia index (RHI) as a measure of an endothelial function 2.0 and mean was 2.0 ± 0.4. During a 5-year follow-up, the 30 patients who developed major adverse cardiovascular events (MACE), including all-cause mortality, nonfatal myocardial infarction, hospitalization for heart failure or angina pectoris, stroke, coronary artery bypass grafting, and percutaneous coronary interventions, had higher 10-year FRS (9.6 ± 7.8 vs. 6.3 ± 5.6%; P  = 0.032), higher 10-year ASCVD risk (10.4 ± 9.2 vs. 6.7 ± 6.9%; P  = 0.042), lower baseline RHI (1.6 ± 0.5 vs. 2.1 ± 0.4; P  < 0.001) and a greater degree of coronary atherosclerotic lesions (53 vs. 3%, P  < 0.001) on CCTA compared with patients without MACE. Multivariate analysis demonstrated that RHI below the median was an independent predictor of 5-year MACE (odds ratio 5.567, 95% confidence interval 1.955-15.853; P  = 0.001).

CONCLUSION

Our findings suggest that noninvasive endothelial function testing may contribute to clinical efficacy in triaging patients in the CPU and in predicting 5-year MACE.

CLINICAL TRIALSGOV IDENTIFIER

NCT01618123.