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Patients with heart failure with preserved ejection fraction (HFpEF) are often elderly and likely to have cardiac comorbidities such as coronary artery disease (CAD) and atrial fibrillation (AF). The primary chronic symptom of HFpEF patients is severe exercise intolerance. The inability to adequately increase heart rate during exercise is commonly present in HFpEF patients and contributes to their exercise intolerance. Although beta-blockers are frequently used for the treatment of myocardial ischemia and tachycardia in HFpEF patients, there is a concern that slowing heart rate by beta-blockers may worsen chronotropic incompetence and further exacerbate their symptoms. Although the effect of beta-blockers on heart failure severity in HFpEF patients has been examined in randomized controlled trials (RCTs), results are inconsistent due partly to limited power. We aimed to conduct a meta-analysis of RCTs on the effect of beta-blockers on heart failure severity in HFpEF patients. The search of electronic databases identified 5 RCTs including 538 patients. In pooled analyses, beta-blockers did not significantly change the New York Heart Association (NYHA) class, exercise capacity expressed as metabolic equivalents, or plasma B-type natriuretic peptide (BNP) levels compared with control but with substantial heterogeneity across trials. In meta-regression analyses, the higher proportion of CAD or AF in the included trials was associated with a decrease in NYHA class and BNP levels and with an increase in exercise capacity. Thus, we found no clear beneficial effect of beta-blockers on heart failure severity in HFpEF patients. However, beta-blockers may be beneficial in HFpEF patients with CAD or AF.

Despite the major progress in the treatment of heart failure, the burden of heart failure is steadily increasing in the Western world. Heart failure is characterized by increased sympathetic activity, and chronic sympathetic activation is involved in the maintenance of the pathological state. Recent studies have shown that catheter-based renal denervation (RDN) presents a safe and minimally invasive treatment option for uncontrolled hypertension, a condition that is driven by increased sympathetic activity. Although randomized controlled trials (RCTs) have examined the effect of RDN in heart failure patients, results are inconsistent due partly to limited power with small sample sizes. We aimed to conduct a meta-analysis of RCTs on the effect of RDN in heart failure patients with reduced left ventricular (LV) ejection fraction (EF). Electronic search identified 5 RCTs including 177 patients. In the pooled analysis, RDN increased LVEF (weighted mean difference (WMD) [95% CI] = 6.289 [1.883, 10.695]%) and 6-min walk distance (61.063 [24.313, 97.813] m) and decreased B-type natriuretic peptide levels (standardized mean difference [95% CI] = − 1.139 [− 1.824, − 0.454]) compared with control. In contrast, RDN did not significantly change estimated glomerular filtration rate (WMD [95% CI] = 5.969 [− 2.595, 14.533] ml/min/1.73 m2) and systolic (− 1.991 [− 15.639, 11.655] mmHg) or diastolic (− 0.003 [− 10.325, 10.320] mmHg) blood pressure compared with control. Our meta-analysis suggests that RDN may improve LV function and exercise capacity in heart failure patients with reduced EF, providing the rationale to conduct large-scale multicenter trials to confirm the observed potential benefits of RDN.

Targeting the renin-angiotensin system (RAS) pathways has been considered a logical intervention for patients with heart failure with preserved ejection fraction (HFpEF), due to its hypothesized link to left ventricular (LV) remodeling. Although the effects of RAS inhibitors including angiotensin-converting enzyme inhibitors (ACE-Is), angiotensin receptor blockers (ARBs), and direct renin inhibitors (DRIs) on LV structure and function and exercise capacity in HFpEF patients have been examined in multiple randomized controlled trials (RCTs), results are inconsistent due partly to limited power. We conducted a meta-analysis of RCTs on the effects of RAS inhibitors on LV structure and function as well as exercise capacity in HFpEF patients. The search of electronic databases identified 7 trials including 569 patients; 4 trials were on ACE-Is; 2 on ARBs; and 1 on DRIs. Follow-up duration ranged across trials from 12 to 52 weeks. The pooled analysis showed that RAS inhibitors significantly increased EF compared with control (weighted mean difference [95% CI] = 2.182 [0.462, 3.901] %). In contrast, RAS inhibitors did not significantly change the ratio of peak early to late diastolic mitral inflow velocities (weighted mean difference [95% CI] = 0.046 [− 0.012, 0.105]), early diastolic mitral annular velocity (0.327 [− 0.07, 0.725] cm/s), the ratio of early diastolic mitral inflow to annular velocities (0.291 [− 0.937, 1.518]), LV mass (− 6.254 [− 15.165, 2.656] g), or 6-min walk distance (1.972 [− 14.22, 18.163] m) compared with control. The present meta-analysis suggests that RAS inhibitors may increase LVEF in HFpEF patients.

Despite the high mortality rate, there is no therapy to improve survival in heart failure with preserved ejection fraction (HFpEF). Large randomized controlled trials (RCTs) did not show clear mortality benefit of renin-angiotensin system (RAS) inhibitors (angiotensin-converting enzyme inhibitors or angiotensin receptor blockers) in HFpEF. However, because of the strict enrollment criteria, the patients who participated in these trials might represent a selected group of patients that is poorly representative of patients treated in routine clinical practice. In contrast, clinical characteristics of real-world patients are similar to those of patients enrolled in observational cohort studies (OCSs). Although many OCSs have examined the prognostic effect of RAS inhibitors in HFpEF, the results are inconsistent due to limited power with small sample sizes and/or inadequate adjustment for known prognostic factors. We aimed to conduct a meta-analysis of OCSs with and those without propensity score (PS) analysis and RCTs on the effect of RAS inhibitors on mortality in HFpEF patients. The search of electronic databases identified 4 OCSs with PS analysis (10,164 patients), 8 OCSs without PS analysis (16,393 patients), and 3 RCTs (8001 patients). Use of RAS inhibitors was associated with reduced mortality in the pooled analysis of OCSs with PS analysis (RR [95% CI] = 0.90 [0.81-1.00]) and in that of OCSs without PS analysis (0.81 [0.68-0.96]) but not in that of RCTs (0.99 [0.87-1.12]). In conclusion, the present meta-analysis suggests the potential mortality benefit of RAS inhibitors in HFpEF, emphasizing the importance of conducting new well-designed RCTs.

Left ventricular (LV) diastolic dysfunction is associated with the pathophysiology of heart failure with preserved ejection fraction (HFpEF) and contributes importantly to exercise intolerance that results in a reduced quality of life (QOL) in HFpEF patients. Although the effects of exercise training on LV diastolic function, exercise capacity, or QOL in HFpEF patients have been examined in randomized clinical trials (RCTs), results are inconsistent due partly to limited power with small sample sizes. We aimed to conduct a meta-analysis of RCTs examining the effects of exercise training on LV diastolic function and exercise capacity as well as QOL in HFpEF patients. The search of electronic databases identified 8 RCTs with 436 patients. The duration of exercise training ranged from 12 to 24 weeks. In the pooled analysis, exercise training improved peak exercise oxygen uptake (weighted mean difference [95% CI], 1.660 [0.973, 2.348] ml/min/kg), 6-min walk distance (33.883 [12.384 55.381] m), and Minnesota Living With Heart Failure Questionnaire total score (9.059 [3.083, 15.035] point) compared with control. In contrast, exercise training did not significantly change early diastolic mitral annular velocity (weighted mean difference [95% CI], 0.317 [− 0.952, 1.587] cm/s), the ratio of early diastolic mitral inflow to annular velocities (− 1.203 [− 4.065, 1.658]), or LV ejection fraction (0.850 [− 0.128, 1.828] %) compared with control. In conclusion, the present meta-analysis suggests that exercise training improves exercise capacity and QOL without significant change in LV systolic or diastolic function in HFpEF patients.

Influenza infection is associated with increased risk for mortality and hospitalization in heart failure patients. Although there are no published randomized controlled trials examining the effect of influenza vaccination on clinical outcomes in heart failure patients, the effect has been examined in observational cohort studies. Nevertheless, results are inconsistent due partly to limited power with small sample sizes and use of different definitions of outcomes. We therefore aimed to conduct a systematic review and meta-analysis of the effect of influenza vaccination on mortality and hospitalization in heart failure patients. The search of electronic databases identified 6 observational cohort studies with 22,486 patients examining the effect of influenza vaccination on mortality and hospitalization in heart failure patients. Pooled analysis of confounder-adjusted hazard ratio showed that influenza vaccination was associated with reduced risk of mortality during 1-year follow-up (risk ratio [95% CI] = 0.76 [0.63–0.92], Pfix

Despite the recent advances in the management of heart failure, the mortality of heart failure patients remains high. It is of urgent need to develop new therapy for heart failure. Heart failure is characterized by increased sympathetic activity, and chronic sympathetic activation is involved in the maintenance of the pathological state. Catheter-based renal denervation (RDN) has emerged as an invasive but safe approach that can reduce sympathetic activation. Studies have reported inconsistent results regarding the effect of RDN in heart failure patients due to limited power with small sample sizes. We aimed to conduct a meta-analysis of the effect of RDN on heart failure patients with reduced left ventricular (LV) ejection fraction (EF). An electronic search for studies examining the effect of RDN on LV function in heart failure patients with reduced EF was conducted. Two controlled (80 patients) and 2 uncontrolled studies (21 patients) were included in this meta-analysis. In the pooled analysis, 6 months after RDN, there was a greater increase in EF (weighted mean difference [95% CI] = 8.63 [6.02, 11.24] %) and a greater decrease in LV end-diastolic diameter (−0.58 [−0.83, −0.34] cm) in RDN group than in control group. No serious adverse events such as acute renal artery stenosis and dissection occurred. Our meta-analysis of feasibility studies suggests that RDN may improve LV function in heart failure patients with reduced EF, providing the rationale to conduct next phase trials to confirm the observed potential benefits of RDN.