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Editorial commentary: Cardiac rehabilitation: Major benefits and minor risks

Trends in Cardiovascular Medicine, Volume 27, Issue 6, August 2017, Pages 426-427

Jennifer G. Foster, Steven F. Lewis, Charles H. Hennekens

Abstract

Cardiac rehabilitation is a valuable treatment for patients with a broad spectrum of cardiac disease. Current guidelines support its use in patients after acute coronary syndrome, coronary artery bypass grafting, coronary stent placement, valve surgery, and stable chronic systolic heart failure. Its use in these conditions is supported by a robust body of research demonstrating improved clinical outcomes. Despite this evidence, cardiac rehabilitation referral and attendance remains low and interventions to increase its use need to be developed.

Introduction

Cardiac rehabilitation (CR) has evolved from exercise only into a comprehensive program that also addresses other cardiovascular disease risk factors and provides education and social support [1]. CR classically consists of three phases. Phase I refers to inpatient rehabilitation during the index hospitalization. Due to the increasingly shorter durations of hospital stay, phase I CR has become less formalized. Phase II refers to physician supervised, outpatient monitored physical activity during the 4 months after discharge. Patients usually undergo up to 36 sessions in a graduated exercise program. Thereafter, patients may continue into phase III, which is an enduring unmonitored exercise program. CR programs also provide nutritional, psychological and smoking cessation counseling, as well as lipid and blood pressure management. Medicare and most insurance carriers provide coverage for this service after acute coronary syndrome, percutaneous coronary intervention (PCI), coronary artery bypass grafting (CABG), valve surgery, and chronic stable heart failure with reduced ejection fraction (HFrEF) [2]. The American Heart Association (AHA) and American College of Cardiology (ACC) consider CR a Class I indication for these conditions [3], [4].

The exercise prescription at CR centers optimally starts with a pre-exercise-training, symptom limited, exercise tolerance test. Thereafter, workouts typically consist of a brief warm up period, followed by supervised individualized aerobic exercise, and a brief cool down phase. The aerobic exercise consists of 20–60 min workouts 3–5 days a week at 50–80% of maximal exercise capacity [1]. Relatively recent data suggest that high intensity interval training (HIIT) produces larger and more rapid increases in exercise capacity [5], [6], [7]. A trial of 27 patients with stable ischemic cardiomyopathy randomized to either moderate continuous training at 70% of their max predicted heart rate or to HIIT at 95% peak heart rate or to a exercise–advise-only control group demonstrated a 46 vs 14% (p<0.001) increase in peak oxygen consumption (VO2MAX) in the HIIT vs continuous training group [5]. Higher VO2MAX has been associated with lower mortality rates in patients with coronary artery disease (CAD) [8]. HIIT also improved endothelial function, reversed left ventricular remodeling, and increased ejection fraction more than continuous training [5]. Similar superior improvements have been noted in other studies [6], [7]. Yet it should not be forgotten that the favorable meta-analyses of CR showing reductions in total mortality and rehospitalizations were based upon the utilization of moderate intensity exercise [9].

Section snippets

The role of exercise training

Many of the benefits of CR are derived from exercise training. Exercise training increases VO2MAX and endurance capacity or the ability to maintain physical activity for extended periods of time [5]. Exercise training has multiple other potentially beneficial effects including improving endothelial function [5], [10], myocardial flow reserve [11] reducing smoking, body weight, blood lipids, and blood pressure [12]. Exercise training has even been shown to reduce the progression of coronary

Coronary artery disease (CAD)

CAD is the most common referral diagnosis to CR centers. Exercise training or CR in patients with CAD increases exercise tolerance and quality of life [5], [6], [15], [16], [17], decreases angina [18], ischemia [19], subsequent hospitalizations [15], [17], and mortality [9], [15].

The AHA/ACC recommends the referral of patients after myocardial infarction (MI) or coronary revascularization and those with stable angina to CR [4] because multiple meta-analysis have demonstrated that CR reduces

Valvular heart disease

The evidence supporting CR for CAD patients is robust, whereas there are less data on CR for patients after valve surgery. An attempt to perform a meta-analysis of randomized, controlled trials of CR after valve surgery found only 2 trials worthy of inclusion. There was an increase in exercise capacity with CR (standard mean difference: −0.47 kJ, CI −0.81-0.13) [28], but too few participants (N=148) to evaluate other outcomes. A retrospective review of patients participating in CR after valve

Heart failure

Medicare initiated coverage of CR for patients with HFrEF in 2014. Patients are eligible for coverage if they have stable heart failure with a left ventricular ejection fraction (LVEF) <35% and New York Heart Association (NYHA) class II to IV symptoms despite at least 6 weeks of appropriate medical management [33].

The exercise training meta-analysis of trials in patients with chronic heart failure or ExTraMatch study provided evidence that exercise training benefits patients with heart failure

Cardiac transplant

Cardiac transplant patients represent a small portion of those referred for cardiac rehabilitation, but these patients are typically profoundly deconditioned due to their pre transplant severe heart failure, prolonged hospital course, and side effects of immunologic therapies. Additionally, the heart is initially denervated in cardiac transplant patients reducing their physiologic response to exercise. Peak VO2 in patients post cardiac transplant recipients is reportedly 70% less than age

Challenges and future directions

Available data and guidelines strongly support the role of comprehensive CR in patients with heart disease. Patients benefit from decreased mortality, morbidity, disability, and increased quality of life. CR patients also benefit from reduced hospitalizations, an increasingly important measure as healthcare moves towards a capitated environment. Despite this, only 14% of patients after AMI and 31% in patients after CABG participate in CR [40]. Future studies should focus on how to include more

Conclusions

CR is a valuable treatment for a broad spectrum of patients with heart disease. It use is supported by a robust body of research demonstrating improvements in cardiopulmonary fitness, psychological factors, and quality of life and reductions in morbidity and mortality. It is also an excellent strategy for reducing hospital readmissions. Despite this evidence, the value of CR is underappreciated and underutilized by many clinicians to the detriment of patient outcomes.