A Meta-analysis of the effects of Exercise Training on Left Ventricular Remodeling Following Myocardial Infarction: Start early and go longer for greatest exercise benefits on remodeling

Abstract

BackgroundThe effects of variations in exercise training on Left ventricular (LV) remodeling in patients shortly after Myocardial Infarction (MI) are important but poorly understood.MethodsSystematic review incorporating meta-analysis using meta-regression. Studies were identified via systematic searches of: OVID MEDLINE (1950 to 2009), Cochrane Central Register of Controlled Trials (1991 to 2009), AMED (1985 to 2009), EMBASE (1988 to 2009), PUBMED (1966 to 2009), SPORT DISCUS (1975 to 2009), SCOPUS (1950 to 2009) and WEB OF SCIENCE (1950 to 2009) using the medical subject headings: myocardial infarction, post myocardial infarction, post infarction, heart attack, ventricular remodeling, ventricular volumes, ejection fraction, left ventricular function, exercise, exercise therapy, kinesiotherapy, exercise training. Reference lists of all identified studies were also manually searched for further relevant studies. Studies selected were randomized controlled trials of exercise training interventions reporting ejection fraction (EF) and/or ventricular volumes in patients following recent MI (≤ 3 months) post-MI patients involving control groups. Studies were excluded if they were not randomized, did not have a 'usual-care' control (involving no exercise), evaluated a non-exercise intervention, or did not involve human subjects. Non-English studies were also excluded.ResultsAfter screening of 1029 trials, trials were identified that reported EF (12 trials, n = 647), End Systolic Volumes (ESV) (9 trials, n = 475) and End Diastolic Volumes (EDV) (10 trials, n = 512). Meta-regression identified that changes in EF effect size difference decreased as the time between MI and initiation of the exercise program lengthened, and increased as the duration of the program increased (Q = 25.48, df = 2, p < 0.01, R2 = 0.76). Greater reductions in ESV and EDV (as indicated by effect size decreases) occurred with earlier initiation of exercise training and with longer training durations (ESV: Q = 23.89, df = 2, p < 0.05, R2 = 0.79; EDV: Q = 27.42, df = 2, p < 0.01, R2 = 0.83). Differences remained following sensitivity analysis. Each week that exercise was delayed required an additional month of training to achieve the same level of benefit on LV remodeling.ConclusionsExercise training has beneficial effects on LV remodeling in clinically stable post-MI patients with greatest benefits occurring when training starts earlier following MI (from one week) and lasts longer than 3 months.

Effect of endurance exercise training on morphological changes in rat heart tissue following experimental myocardial infarction

“…Researches has shown that in order to achieve the maximum cardioprotection benefits of exercise and prevent adverse LV remodeling, post-MI patients should start aerobic exercise for about 1 week after discharge from the hospital and continue for longer duration (approx. 6 months) (8). Therefore, one of the reasons for inconsistent results of the present study with previous ones is probably less duration of training following MI.…”

“…However, the results of research about the effects of exercise on post-MI cardiac morphological remodeling is contradictory. For example, Haykowsky et al (2011) reported that exercise training after infarction (started 1 week after MI) improved LV remodeling (8). However, Batista et al (2013), in assessment of effects of three-month endurance exercise training, which started 5 and 21 days after MI, reported that the infarct size was not different in experimental groups compared with control group (6).…”

Delays in Referral and Enrolment Are Associated With Mitigated Benefits of Cardiac Rehabilitation After Coronary Artery Bypass Surgery

“…In a metaregression analysis, Haykowsky et al reported that patients who started exercise training earlier post-MI had greater beneficial effects on left ventricular remodeling (increased ejection fraction and decreased end diastolic and systolic volumes). 41 Improved left ventricular remodeling may in part explain the underlying mechanism for greater improvement in VȮ 2peak and resting heart rate for those who started CR earlier in the current study. Also, if later entry to CR was a patient choice, this may be a proxy for lack of motivation to engage in lifestyle change and thus a mediator of less favorable change in VȮ 2peak and body composition.…”

Cardiorespiratory fitness, oxygen pulse and heart rate response following the MyAction programme

“…Starting within this time frame has been shown to be both safe and feasible [19][20][21][22] as well as improving patient uptake and adherence [23] . The gains from early cardiac rehabilitation also include the potential to reduce unplanned readmissions early in the discharge period (within 30 days) thus yielding significant cost savings.…”