Selective improvement in Seattle Heart Failure Model risk stratification using iodine-123 meta-iodobenzylguanidine imaging

BACKGROUND

The Seattle Heart Failure Model (SHFM) is a multivariable model that uses demographic and clinical markers to predict survival in patients with heart failure. Inappropriate activation of the sympathetic nervous system, which contributes to the progression of heart failure and increased mortality, can be assessed using iodine-123 meta-iodobenzylguanidine (MIBG) cardiac imaging. This study investigated the incremental value of MIBG cardiac imaging when added to the SHFM for prediction of all-cause mortality.

METHODS

Survival data from 961 NYHA II-III subjects in the ADMIRE-HFX trial were included in this analysis. The predictive value of the SHFM alone and in combination with MIBG heart-to-mediastinum ratio (H/M) was compared for all-cause mortality (101 deaths during a median follow-up of 2 years).

RESULTS

The addition of H/M to the SHFM in a Cox model significantly improved risk prediction (P < .0001), with a greater utility in higher risk SHFM patients. The observed 2-year mortality in the highest-risk SHFM subjects (rounded SHFM score of 1) was 24%, but varied from 46% with H/M <1.2 to 0% with H/M >1.8. Net reclassification improvement was 22.7% (P < .001), with 14.9% of subjects who died reclassified into a higher risk category than suggested by SHFM score alone (P = .01) and 7.9% of subjects who survived reclassified into a lower risk category (P < .0001). The 2-year integrated discrimination improvement (+4.14%, P < .0001) and the 1-year area under the receiver-operator characteristic curve (+0.04, P = .026) both showed significant improvement for the combined model with H/M compared to the SHFM alone.

CONCLUSION

The addition of MIBG imaging to the SHFM improves risk stratification, especially in higher risk patients. MIBG may have clinical utility in higher risk patients who are being considered for devices such as ICD, CRT-D, LVAD, and cardiac transplantation.

Contrast stress-echocardiography predicts cardiac events in patients with suspected acute coronary syndrome but nondiagnostic electrocardiogram and normal 12-hour troponin

BACKGROUND

No large study has demonstrated that any stress test can risk-stratify future hard cardiac events (cardiac death or myocardial infarction) in patients with suspected acute coronary syndromes (ACS), nondiagnostic electrocardiographic (ECG) findings, and normal troponin levels. The aim of this study was to test the hypothesis that combined contrast wall motion and myocardial perfusion echocardiographic assessment (cMCE) during stress echocardiography can predict long-term hard cardiac events in patients with suspected ACS, nondiagnostic ECG findings, and normal troponin.

METHODS

A total of 545 patients referred for contrast stress echocardiography from the emergency department for suspected ACS but nondiagnostic ECG findings and normal troponin levels at 12 hours were followed up for cardiac events. Patients underwent dipyridamole-atropine echocardiography with adjunctive myocardial perfusion imaging using a commercially available ultrasound contrast medium (SonoVue).

RESULTS

During a median follow-up period of 12 months, 25 cardiac events (4.6%) occurred (no deaths, 12 nonfatal myocardial infarctions, 13 episodes of unstable angina). Abnormal findings on cMCE were the most significant predictor of both hard cardiac events (hazard ratio, 22.8; 95% confidence interval, 2.9-176.7) and the combined (cardiac death, myocardial infarction, or unstable angina requiring revascularization) end point (hazard ratio, 10.7; 95% confidence interval, 3.7-31.3). The inclusion of the cMCE variable significantly improved multivariate models, determining lower Akaike information criterion values and higher discrimination ability.

CONCLUSIONS

cMCE during contrast stress echocardiography provided independent information for predicting hard and combined cardiac events beyond that predicted by stress wall motion abnormalities in patients with suspected ACS, nondiagnostic ECG findings, and normal troponin levels.

Does subclinical atherosclerosis burden identify the increased risk of cardiovascular disease mortality among United Kingdom Indian Asians? A population study

BACKGROUND

Indian Asians living in the United Kingdom have a >50% higher risk of cardiovascular disease (CVD) death compared with native European whites. The mechanisms underlying their excess mortality are not clear, and there are no validated tools capable of identifying this increased risk. The burden of subclinical atherosclerosis detected in the carotid arteries is an established prognosticator for major CVD events. We hypothesized that the increased prevalence of CVD among Indian Asians would be reflected by their having a greater burden of subclinical carotid artery atherosclerosis compared with European whites.

METHODS

We studied 2,288 healthy subjects and 148 patients with known CVD from the London Life Sciences Prospective Population study who underwent carotid ultrasonography for assessment of intima-media thickness (IMT), plaque prevalence, and plaque echogenicity.

RESULTS

The prevalence of CVD was significantly higher among Indian Asians compared with European whites (odds ratio 1.72, 95% CI 1.2-2.3). Intima-media thickness was slightly higher in European whites compared with that of Indian Asians (0.66 vs 0.65 mm, P = .06), reflecting their higher Framingham Risk Score. After adjustment for cardiovascular risk factors, there were no significant differences in IMT, plaque prevalence, or plaque echogenicity between the 2 ethnic groups regardless of CVD status.

CONCLUSION

The burden of carotid atherosclerosis does not identify the markedly increased risk of CVD among United Kingdom Indian Asians. Other markers and mechanisms of disease require investigation in this high-risk group.

The effects of the cardiac myosin activator, omecamtiv mecarbil, on cardiac function in systolic heart failure: a double-blind, placebo-controlled, crossover, dose-ranging phase 2 trial

BACKGROUND

Many patients with heart failure remain symptomatic and have a poor prognosis despite existing treatments. Decreases in myocardial contractility and shortening of ventricular systole are characteristic of systolic heart failure and might be improved by a new therapeutic class, cardiac myosin activators. We report the first study of the cardiac myosin activator, omecamtiv mecarbil, in patients with systolic heart failure.

METHODS

We undertook a double-blind, placebo-controlled, crossover, dose-ranging, phase 2 trial investigating the effects of omecamtiv mecarbil (formerly CK-1827452), given intravenously for 2, 24, or 72 h to patients with stable heart failure and left ventricular systolic dysfunction receiving guideline-indicated treatment. Clinical assessment (including vital signs, echocardiograms, and electrocardiographs) and testing of plasma drug concentrations took place during and after completion of each infusion. The primary aim was to assess safety and tolerability of omecamtiv mecarbil. This study is registered at ClinicalTrials.gov, NCT00624442.

FINDINGS

45 patients received 151 infusions of active drug or placebo. Placebo-corrected, concentration-dependent increases in left ventricular ejection time (up to an 80 ms increase from baseline) and stroke volume (up to 9·7 mL) were recorded, associated with a small reduction in heart rate (up to 2·7 beats per min; p<0·0001 for all three measures). Higher plasma concentrations were also associated with reductions in end-systolic (decrease of 15 mL at >500 ng/mL, p=0·0026) and end-diastolic volumes (16 mL, p=0·0096) that might have been more pronounced with increased duration of infusion. Cardiac ischaemia emerged at high plasma concentrations (two patients, plasma concentrations roughly 1750 ng/mL and 1350 ng/mL). For patients tolerant of all study drug infusions, no consistent pattern of adverse events with either dose or duration emerged.

INTERPRETATION

Omecamtiv mecarbil improved cardiac function in patients with heart failure caused by left ventricular dysfunction and could be the first in class of a new therapeutic agent.

FUNDING

Cytokinetics Inc.

Stress-induced Myocardial Ischaemia – Perfusion Contrast Echocardiography to Evaluate Presence and Severity of Coronary Artery Disease

The development of stable transpulmonary ultrasound contrast agents (UCAs) has allowed the echocardiographic assessment of myocardial perfusion, a technique known as myocardial contrast echocardiography (MCE). MCE exploits the ultrasonic properties of UCAs, which consist of acoustically active gas-filled microspheres. These are intravascular agents that have a rheology similar to red blood cells and thus allow analysis of myocardial blood flow both at rest and after stress. The combined assessment of wall motion and myocardial perfusion provides significant diagnostic and prognostic information during stress echocardiography. Functional imaging tests, such as myocardial perfusion scintigraphy and stress cardiac magnetic resonance imaging, are also used for non-invasive assessment of coronary disease. The principal advantages of MCE are that it does not expose the patient to ionising radiation or radioactive pharmaceuticals, is not contraindicated in patients with an implanted metallic device or who suffer from claustrophobia and it can be performed at the bedside. The purpose of this article is to outline the physiological principles underpinning ischaemia testing with MCE before proceeding to review the evidence base for MCE in patients with known or suspected coronary artery disease.

Pathological and physiological left ventricular hypertrophy: echocardiography for differentiation

Distinguishing physiological left ventricular hypertrophy of an athlete's heart from that of pathological left ventricular (hypertrophic cardiomyopathy) can be difficult despite the advent of new imaging techniques. Nevertheless, the final diagnosis is of utmost importance as it will have a profound impact on an individual's life. A diagnosis of hypertrophic cardiomyopathy essentially excludes an individual from sport and strenuous exertion and necessitates the need for further tests and treatment, as well as the screening of family members. Hypertrophic cardiomyopathy remains the most common cause of a pathologically hypertrophied heart in young athletes, with a prevalence of one in 500. The issue of sudden death in athletes due to pathological left ventricular hypertrophy and hypertrophic cardiomyopathy has recently gained recognition owing to the death of several word class athletes during sporting participation. What compounds this further is the fact that a proportion of athletes fall into the 'grey zone' (ventricular wall thickness of 13-16 mm) where the increase in cardiac size overlaps with the phenotypic variation of hypertrophic cardiomyopathy - making echocardiographic differentiation of the two entities challenging. This review discusses the echocardiographic differentiation of the athlete's heart, including physiological left ventricular hypertrophy from pathological left ventricular hypertrophy. Although several of the cardiomyopathies cause pathological left ventricular hypertrophy, focus will be given to hypertrophic cardiomyopathy, for reasons mentioned above. Discussion will also focus on the newer and emerging echocardiographic techniques for this purpose. The term 'hypertrophic cardiomyopathy' is used to describe the nonobstuctive form of hypertrophic cardiomyopathy as this review article focuses on distinguishing the 'mild' form of hypertrophic cardiomyopathy from an athlete's heart. When the more severe obstructive form is being described, the term 'hypertrophic obstructive cardiomyopathy' is used.

Age-dependent values of N-terminal pro-B-type natriuretic peptide are superior to a single cut-point for ruling out suspected systolic dysfunction in primary care

AIMS

The study evaluated the use of age-related decision limits for N-terminal pro-B-type natriuretic peptide (NT-proBNP), for ruling out suspected systolic dysfunction in symptomatic patients in primary care, compared with the present standards.

METHODS AND RESULTS

Data were obtained from 5508 patients from 10 studies in the UK, New Zealand, Europe, and USA. All have had NT-proBNP analysis and echocardiography. The median age was 62 years (range 18-100 years) with a prevalence of reduced left ventricular systolic function (left ventricular ejection fraction < or =40%) of 18%. In a receiver operating characteristic curve analysis, overall area under the curve (AUC) was 0.89. When looking at different age groups, AUC was highest (0.95) for <50 years, intermediate (0.90) for 50-75 years, and lowest (0.82) for >75 years. Using optimized decision limits, sensitivity, specificity, and negative predictive values (NPVs) were: <50 years (50 ng/L): 99.2, 57.2, and 99.7%; 50-75 years (75 ng/L): 95.9, 51.0, and 96.8%; and >75 years (250 ng/L): 87.9, 53.7, and 92.4%, respectively. Using only a single decision value (125 ng/L for all ages) gave sensitivities of 89.1, 91.9, and 94.3%; specificities of 84.0, 69.1, and 29.3% and NPVs of 97.7, 97.6, and 93.4%. A decision value of 400 ng/L for all ages gave much lower sensitivities.

CONCLUSION

In a large population of patients in primary care, the use of age-stratified NT-proBNP decision limits considerably improves performance over current standards, with an excellent NPV for exclusion of reduced left ventricular systolic function.