Implications of geographical variation on clinical outcomes of cardiovascular trials.

Cardiovascular clinical trials are increasingly conducted globally as a means to reduce costs, expedite timelines, provide broad applicability, and satisfy regulatory authorities. Potential problems with trial globalization include regional differences in patient characteristics, medical practice patterns, and health policies which may influence outcomes and limit generalizability. Moreover, concerns have been raised about ethical misconduct and unsatisfactory quality oversight in regions with less trial experience and infrastructure. This article reviews geographical differences in cardiovascular trials in heart failure, acute coronary syndromes, hypertension and atrial fibrillation. It also explores potential explanations for these differences and methods to standardize the presentation of trial results. This review is based on discussions between basic scientists and clinical trialists at the 8th Global Cardio Vascular Clinical Trialists Forum 2011 in Paris, France, from December 2 to 3.

A randomized controlled trial evaluating the safety and efficacy of cardiac contractility modulation in advanced heart failure.

BACKGROUND: Cardiac contractility modulation (CCM) delivers nonexcitatory electrical signals to the heart during the absolute refractory period intended to improve contraction. METHODS: We tested CCM in 428 New York Heart Association class III or IV, narrow QRS heart failure patients with ejection fraction (EF) ≤ 35% randomized to optimal medical therapy (OMT) plus CCM (n = 215) versus OMT alone (n = 213). Efficacy was assessed by ventilatory anaerobic threshold (VAT), primary end point, peak Vo2 (pVo2), and Minnesota Living with Heart Failure Questionnaire (MLWFQ) at 6 months. The primary safety end point was a test of noninferiority between groups at 12 months for the composite of all-cause mortality and hospitalizations (12.5% allowable delta). RESULTS: The groups were comparable for age (58 ± 13 vs 59 ± 12 years), EF (26% ± 7% vs 26% ± 7%), pVo2 (14.7 ± 2.9 vs 14.8 ± 3.2 mL kg⁻¹ min⁻¹), and other characteristics. While VAT did not improve at 6 months, CCM significantly improved pVo2 and MLWHFQ (by 0.65 mL kg⁻¹ min⁻¹ [P = .024] and -9.7 points [P < .0001], respectively) over OMT. Forty-eight percent of OMT and 52% of CCM patients experienced a safety end point, which satisfied the noniferiority criterion (P = .03). Post hoc, hypothesis-generating analysis identified a subgroup (characterized by baseline EF ≥ 25% and New York Heart Association class III symptoms) in which all parameters were improved by CCM. CONCLUSIONS: In the overall target population, CCM did not improve VAT (the primary end point) but did improve pVo2 and MLWHFQ. Cardiac contractility modulation did not have an adverse affect on hospitalizations or mortality within the prespecified boundaries. Further study is required to clarify the role of CCM as a treatment for medically refractory heart failure.

Subgroup analysis of a randomized controlled trial evaluating the safety and efficacy of cardiac contractility modulation in advanced heart failure.

BACKGROUND: Cardiac contractility modulation (CCM) signals are nonexcitatory electrical signals delivered during the absolute refractory period intended to improve contraction. We previously tested the safety and efficacy of CCM in 428 NYHA functional class III/IV heart failure patients with EF ≤35% and narrow QRS randomized to optimal medical treatment (OMT) plus CCM (n = 215) versus OMT alone (n = 213) and found no significant effect on ventilatory anaerobic threshold (VAT), the study's primary end point. In the present analysis, we sought to identify if there was a subgroup of patients who showed a response to CCM. METHODS AND RESULTS: The protocol specified that multiregression analysis would be used to determine if baseline EF, NYHA functional class, pVO(2), or etiology of heart failure influenced the impact of CCM on AT. Etiology and baseline pVO(2) did not affect efficacy. However, baseline NYHA functional class III and EF ≥25% were significant predictors of increased efficacy. In this subgroup (comprising 97 OMT and 109 CCM patients, ∼48% of the entire population) VAT increased by 0.10 ± 2.36 in CCM versus -0.54 ± 1.83 mL kg(-1) min(-1) in OMT (P = .03) and pVO(2) increased by 0.34 ± 3.11 in CCM versus -0.97 ± 2.31 (P = .001) at 24 weeks compared with baseline; 44% of CCM versus 23% of OMT subjects showed improvement of ≥1 class in NYHA functional class (P = .002), and 59% of CCM versus 42% of OMT subjects showed a ≥10-point reduction in Minnesota Living with Heart Failure Questionnaire (P = .01). All of these findings were similar to those seen at 50 weeks. CONCLUSIONS: The results of this retrospective hypothesis-generating analysis indicate that CCM significantly improves objective parameters of exercise tolerance in a subgroup of patients characterized by normal QRS duration, NYHA functional class III symptoms, and EF >25%.

The influence of renal function on clinical outcome and response to beta-blockade in systolic heart failure: insights from Metoprolol CR/XL Randomized Intervention Trial in Chronic HF (MERIT-HF).

BACKGROUND: Limited information is available on the risk and impact of renal dysfunction on the response to beta-blockade and mode of death in systolic heart failure (HF). METHODS AND RESULTS: Renal function was estimated with glomerular filtration rate (eGFR) using the simplified Modification of Diet in Renal Disease (MDRD) equation. Patients from the Metoprolol CR/XL Controlled Randomized Intervention Trial in Chronic HF (MERIT-HF) were divided into 3 renal function subgroups (MDRD formula): eGFR(MDRD) > 60 (n = 2496), eGFR(MDRD) 45 to 60 (n = 976), and eGFR(MDRD) < 45 mL/min per 1.73 m(2) body surface area (n = 493). Hazard ratio (HR) was estimated with Cox proportional hazards models adjusted for prespecified risk factors. Placebo patients with eGFR < 45 had significantly higher risk than those with eGFR > 60: HR for all-cause mortality, 1.90 (95% confidence interval [CI], 1.28 to 2.81) comparing placebo patients with eGFR < 45 and eGFR > 60, and for the combined end point of all-cause mortality/hospitalization for worsening HF (time to first event): HR, 1.91 (95% CI, 1.44 to 2.53). No significant increase in risk with deceased renal function was observed for those randomized to metoprolol controlled release (CR)/extended release (XL) due to a highly significant decrease in risk on metoprolol CR/XL in those with eGFR < 45. For total mortality, metoprolol CR/XL vs placebo: HR, 0.41 (95% CI. 0.25 to 0.68; P < .001) in those with eGFR < 45 compared with HR, 0.71 (95% CI, 0.54 to 0.95; P < .021) for those with eGFR > 60; corresponding data for the combined end point was HR, 0.44 (95% CI, 0.31 to 0.63; P < .0001) and HR, 0.75 (0.62 to 0.92; P = .005, respectively; P = .095 for interaction by treatment for total mortality; P = .011 for combined end point). Metoprolol CR/XL was well tolerated in all 3 renal function subgroups. CONCLUSIONS: Renal function as estimated by eGFR was a powerful predictor of death and hospitalizations from worsening HF. Metoprolol CR/XL was at least as effective in reducing death and hospitalizations for worsening HF in patients with eGFR < 45 as in those with eGFR > 60.

Atenolol is inferior to metoprolol in improving left ventricular function and preventing ventricular remodeling in dogs with heart failure.

OBJECTIVES: beta-Blockers are standard therapy for patients with heart failure (HF). This study compared the effects of chronic monotherapy with 2 different beta(1)-selective adrenoceptor blockers, namely atenolol and metoprolol succinate, on left ventricular (LV) function and remodeling in dogs with coronary microembolization-induced HF [LV ejection fraction (EF) 30-40%]. METHODS: Twenty HF dogs were randomized to 3 months of therapy with atenolol (50 mg once daily, n = 6), metoprolol succinate (100 mg, once daily, n = 7) or to no therapy (control, n = 7). LV EF and volumes were measured before initiating therapy and after 3 months of therapy. The change (Delta) in EF and volumes between measurements before and after therapy was calculated and compared among study groups. RESULTS: In controls, EF decreased and end-systolic volume increased. Atenolol prevented the decrease in EF and the increase in ESV. In contrast, metoprolol succinate significantly increased EF and decreased end-systolic volume. DeltaEF was significantly higher and Deltaend-systolic volume significantly lower in metoprolol succinate-treated dogs compared to atenolol-treated dogs (EF: 6.0 +/- 0.86% vs. 0.8 +/- 0.85%, p < 0.05; end-systolic volume: -4.3 +/- 0.81 ml vs. -1 +/- 0.52 ml, p <0.05). CONCLUSIONS: In HF dogs, chronic therapy with atenolol does not elicit the same LV function and remodeling benefits as those achieved with metoprolol succinate.

Globalization of cardiovascular clinical research: the balance between meeting medical needs and maintaining scientific standards.

A substantial need to conduct research studies and identify effective treatments for cardiovascular diseases in the developing world exists. Careful consideration of several issues is warranted to ensure that clinical trials conducted solely in developing nations are held to accepted scientific standards. Researchers conducting clinical trials in developing countries should critically evaluate the purpose and appropriateness of conducting the trial in the proposed location, the accessibility of the therapy if proven effective, the quality of the informed consent process, the presence of infrastructure to support clinical research, and the translation of data to other populations. This article discusses the importance of these considerations using a recent example of a clinical trial conducted in a developing nation. These and other issues are critical to address as the conduct of cardiovascular clinical trials continues to expand beyond the western world.

Left atrial reverse remodeling in dogs with moderate and advanced heart failure treated with a passive mechanical containment device: an echocardiographic study.

BACKGROUND: Assessment of global left ventricular (LV) remodeling is important in evaluating the efficacy of pharmacologic and device therapies for the treatment of chronic heart failure (HF). The effects of pharmacologic or device therapies on global left atrial (LA) remodeling in HF, although also important, are not often examined. We showed that long-term therapy with the Acorn Cardiac Support Device (CSD), a passive mechanical ventricular containment device, prevents or reverses LV remodeling in dogs with HF. This study examined the effects of the CSD on global LA remodeling in dogs with moderate and advanced HF. METHODS AND RESULTS: Studies were performed in 24 dogs with coronary microembolization-induced HF. Of these, 12 had moderate HF (ejection fraction, EF 30% to 40%) and 12 advanced HF (EF < or = 25%). In each group, the CSD was implanted in 6 dogs and the other 6 served as controls. Dogs were followed for 3 months in the moderate group and 6 months in the advanced HF group. LA maximal volume (LAVmax), LA volume at the onset of the p-wave (LAVp), LA minimal volume (LAVmin), LA active emptying volume (LAAEV), and LA active emptying fraction (LAAEF) were measured from 2-dimensional echocardiograms obtained before CSD implantation and at the end of the treatment period. Treatment effect (delta) comparisons between CSD-treated dogs and controls showed that CSD therapy significantly decreased LA volumes (deltaLAVmax: 3.33 +/- 0.70 vs. -2.87 +/- 1.31 mL, P = .002; 7.77 +/- 1.76 versus -0.37 +/- 0.87 mL, P = .002) and improved LA function (deltaLAAEF: -6.00 +/- 1.53 versus 1.85 +/- 1.32%, P = .003; -2.39 +/- 1.10 versus 3.13 +/- 1.66%, P = .02) in the moderate HF and advanced HF groups, respectively. CONCLUSIONS: Progressive LA enlargement and LA functional deterioration occurs in untreated dogs with HF. Monotherapy with the CSD prevents LA enlargement and improves LA mechanical function in dogs with moderate and advanced HF indicating prevention or reversal of adverse LA remodeling.

Novel Mitochondria-Targeting Peptide in Heart Failure Treatment: A Randomized, Placebo-Controlled Trial of Elamipretide.

BACKGROUND: Mitochondrial dysfunction and energy depletion in the failing heart are innovative therapeutic targets in heart failure management. Elamipretide is a novel tetrapeptide that increases mitochondrial energy; however, its safety, tolerability, and therapeutic effect on cardiac structure and function have not been studied in heart failure with reduced ejection fraction. METHODS AND RESULTS: In this double-blind, placebo-controlled, ascending-dose trial, patients with heart failure with reduced ejection fraction (ejection fraction, ≤35%) were randomized to either a single 4-hour infusion of elamipretide (cohort 1 [n=8], 0.005; cohort 2 [n=8], 0.05; and cohort 3 [n=8], 0.25 mg·kg-1·h-1) or placebo control (n=12). Safety and efficacy were assessed by clinical, laboratory, and echocardiographic assessments performed at pre-, mid- and end-infusion and 6-, 8-, 12- and 24-hours postinfusion start. Peak plasma concentrations of elamipretide occurred at end-infusion and were undetectable by 24 hours postinfusion. There were no serious adverse events. Blood pressure and heart rate remained stable in all cohorts. Compared with placebo, a significant decrease in left ventricular end-diastolic volume (-18 mL; P=0.009) and end-systolic volume (-14 mL; P=0.005) occurred at end infusion in the highest dose cohort. CONCLUSIONS: This is the first study to evaluate elamipretide in heart failure with reduced ejection fraction and demonstrates that a single infusion of elamipretide is safe and well tolerated. High-dose elamipretide resulted in favorable changes in left ventricular volumes that correlated with peak plasma concentrations, supporting a temporal association and dose-effect relationship. Further study of elamipretide is needed to determine long-term safety and efficacy. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02388464.