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The coronavirus disease 2019 (COVID-19) pandemic is associated with significant morbidity and mortality throughout the world, predominantly due to lung and cardiovascular injury. The virus responsible for COVID-19—severe acute respiratory syndrome coronavirus 2—gains entry into host cells via ACE2 (angiotensin-converting enzyme 2). ACE2 is a primary enzyme within the key counter-regulatory pathway of the renin-angiotensin system (RAS), which acts to oppose the actions of Ang (angiotensin) II by generating Ang-(1–7) to reduce inflammation and fibrosis and mitigate end organ damage. As COVID-19 spans multiple organ systems linked to the cardiovascular system, it is imperative to understand clearly how severe acute respiratory syndrome coronavirus 2 may affect the multifaceted RAS. In addition, recognition of the role of ACE2 and the RAS in COVID-19 has renewed interest in its role in the pathophysiology of cardiovascular disease in general. We provide researchers with a framework of best practices in basic and clinical research to interrogate the RAS using appropriate methodology, especially those who are relatively new to the field. This is crucial, as there are many limitations inherent in investigating the RAS in experimental models and in humans. We discuss sound methodological approaches to quantifying enzyme content and activity (ACE, ACE2), peptides (Ang II, Ang-[1–7]), and receptors (types 1 and 2 Ang II receptors, Mas receptor). Our goal is to ensure appropriate research methodology for investigations of the RAS in patients with severe acute respiratory syndrome coronavirus 2 and COVID-19 to ensure optimal rigor and reproducibility and appropriate interpretation of results from these investigations.

Background: Unlike heart failure with reduced ejection fraction, there is no approved treatment for heart failure with preserved ejection fraction, the predominant phenotype in women. Therefore, there is a greater heart failure therapeutic deficit in women compared with men. Methods: In a prespecified subgroup analysis, we examined outcomes according to sex in the PARAGON-HF trial (Prospective Comparison of ARNI With ARB Global Outcomes in Heart Failure With Preserved Ejection Fraction), which compared sacubitril-valsartan and valsartan in patients with heart failure with preserved ejection fraction. The primary outcome was a composite of first and recurrent hospitalizations for heart failure and death from cardiovascular causes. We also report secondary efficacy and safety outcomes. Results: Overall, 2479 women (51.7%) and 2317 men (48.3%) were randomized. Women were older and had more obesity, less coronary disease, and lower estimated glomerular filtration rate and NT-proBNP (N-terminal pro–B-type natriuretic peptide) levels than men. For the primary outcome, the rate ratio for sacubitril-valsartan versus valsartan was 0.73 (95% CI, 0.59–0.90) in women and 1.03 (95% CI, 0.84–1.25) in men ( P interaction = 0.017). The benefit from sacubitril-valsartan was attributable to reduction in heart failure hospitalization. The improvement in New York Heart Association class and renal function with sacubitril-valsartan was similar in women and men, whereas the improvement in Kansas City Cardiomyopathy Questionnaire clinical summary score was less in women than in men. The difference in adverse events between sacubitril-valsartan and valsartan was similar in women and men. Conclusions: As compared with valsartan, sacubitril-valsartan seemed to reduce the risk of heart failure hospitalization more in women than in men. Whereas the possible sex-related modification of the effect of treatment has several potential explanations, the present study does not provide a definite mechanistic basis for this finding. Clinical Trial Registration: https://www.clinicaltrials.gov . Unique identifier: NCT01920711.

Approximately half of the patients with signs and symptoms of heart failure have a left ventricular ejection fraction that is not markedly abnormal. Despite the historically initial surprise, heightened risks for heart failure specific major adverse events occur across the broad range of ejection fraction, including normal. The recognition of the magnitude of the problem of heart failure with preserved ejection fraction in the past 20 years has spurred an explosion of clinical investigation and growing intensity of informative outcome trials. This article addresses the historic development of this component of the heart failure syndrome, including the epidemiology, pathophysiology, and existing and planned therapeutic studies. Looking forward, more specific phenotyping and even genotyping of subpopulations should lead to improvements in outcomes from future trials.

Background: To describe the baseline characteristics of patients with heart failure and preserved left ventricular ejection fraction enrolled in the PARAGON-HF trial (Prospective Comparison of Angiotensin Receptor Neprilysin Inhibitor With Angiotensin Receptor Blocker Global Outcomes in HFpEF) comparing sacubitril/valsartan to valsartan in reducing morbidity and mortality. Methods and Results: We report key demographic, clinical, and laboratory findings, and baseline therapies, of 4822 patients randomized in PARAGON-HF, grouped by factors that influence criteria for study inclusion. We further compared baseline characteristics of patients enrolled in PARAGON-HF with those patients enrolled in other recent trials of heart failure with preserved ejection fraction (HFpEF). Among patients enrolled from various regions (16% Asia-Pacific, 37% Central Europe, 7% Latin America, 12% North America, 28% Western Europe), the mean age of patients enrolled in PARAGON-HF was 72.7±8.4 years, 52% of patients were female, and mean left ventricular ejection fraction was 57.5%, similar to other trials of HFpEF. Most patients were in New York Heart Association class II, and 38% had ≥1 hospitalizations for heart failure within the previous 9 months. Diabetes mellitus (43%) and chronic kidney disease (47%) were more prevalent than in previous trials of HFpEF. Many patients were prescribed angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (85%), β-blockers (80%), calcium channel blockers (36%), and mineralocorticoid receptor antagonists (24%). As specified in the protocol, virtually all patients were on diuretics, had elevated plasma concentrations of N-terminal pro-B-type natriuretic peptide (median, 911 pg/mL; interquartile range, 464–1610), and structural heart disease. Conclusions: PARAGON-HF represents a contemporary group of patients with HFpEF with similar age and sex distribution compared with prior HFpEF trials but higher prevalence of comorbidities. These findings provide insights into the impact of inclusion criteria on, and regional variation in, HFpEF patient characteristics. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov . Unique identifier: NCT01920711.

Background— Patients with chronic kidney disease are at increased risk for cardiovascular morbidity and mortality. We assessed the association between albuminuria and the risks for death and cardiovascular events among patients with stable coronary disease. Methods and Results— We studied patients enrolled in the Prevention of Events with an ACE inhibitor (PEACE) trial, in which patients with chronic stable coronary disease and preserved systolic function were randomized to trandolapril or placebo and followed up for a median of 4.8 years. The urinary albumin to creatinine ratio (ACR) assessed in a core laboratory in 2977 patients at baseline and in 1339 patients at follow-up (mean 34 months) was related to estimated glomerular filtration rate and outcomes. The majority of patients (73%) had a baseline ACR within the normal range (<17 μg/mg for men and <25 μg/mg for women). Independent of the estimated glomerular filtration rate and other baseline covariates, a higher ACR, even within the normal range, was associated with increased risks for all-cause mortality ( P <0.001) and cardiovascular death ( P =0.01). The effect of trandolapril therapy on outcomes was not modified significantly by the level of albuminuria. Nevertheless, trandolapril therapy was associated with a significantly lower mean follow-up ACR (12.5 versus 14.6 μg/mg, P =0.0002), after adjustment for baseline ACR, time between collections, and other covariates. An increase in ACR over time was associated with increased risk of cardiovascular death (hazard ratio per log ACR 1.74, 95% CI 1.08 to 2.82). Conclusions— Albuminuria, even in low levels within the normal range, is an independent predictor of cardiovascular and all-cause mortality.

Background— Data supporting the prognostic significance of high-sensitivity C-reactive protein (hs-CRP) are derived largely from individuals with no overt coronary artery disease or from patients with acute coronary syndromes. In contrast, the ability of hs-CRP to predict outcomes in patients with stable coronary artery disease and the prognostic significance of the Centers for Disease Control/American Heart Association hs-CRP cut points in such a population remain relatively unexplored. Methods and Results— We measured hs-CRP in 3771 patients with stable coronary artery disease from the Prevention of Events With Angiotensin-Converting Enzyme Inhibition (PEACE) trial, a randomized placebo-controlled trial of the angiotensin-converting enzyme inhibitor trandolapril. Patients were followed up for a median of 4.8 years for cardiovascular death, myocardial infarction, or stroke, as well as new heart failure and diabetes. After adjustment for baseline characteristics and treatments, higher hs-CRP levels, even >1 mg/L, were associated with a significantly greater risk of cardiovascular death, myocardial infarction, or stroke (hs-CRP 1 to 3 mg/L: adjusted hazard ratio, 1.39; 95% CI, 1.06 to 1.81; P =0.016; hs-CRP >3 mg/L: adjusted hazard ratio, 1.52; 95% CI, 1.15 to 2.02; P =0.003). Similarly, elevated hs-CRP levels were an independent predictor of new heart failure (adjusted P <0.001 for trend) and new diabetes (adjusted P <0.001 for trend). There were no significant interactions between hs-CRP levels and the effects of trandolapril on any of the above outcomes. Conclusions— In stable coronary artery disease, an elevated hs-CRP level, even >1 mg/L, is a significant predictor of adverse cardiovascular events independently of baseline characteristics and treatments. An elevated hs-CRP does not appear to identify patients with stable coronary artery disease and preserved ejection fraction who derive particular benefit from angiotensin-converting enzyme inhibition.