Abstract 18646: Safety Aspects of High Intensity Interval Training versus Moderate Intensity Continuous Exercise Training in Patients Post Acute Coronary Syndrome

Abstract

Introduction: Exercise training in patients who have suffered an acute coronary syndrome is associated with a significant reduction in mortality and cardiovascular events. Moderate intensity continuous exercise training (MICET) is currently recommended. Recently, high-intensity interval training (HIIT), that utilizes short bursts of very intense efforts interspersed with periods of recovery, has been explored as an alternative to MICET. The safety aspects of HIIT in patients post acute coronary syndrome (ACS) have been poorly described. Methods: Thirty-seven low-risk patients post ACS (65% STEMI, fully revascularized, EF > 40%, age 61±9 years, 8 women) were randomized 4 weeks to 6 months post ACS; to 12 to 18 weeks of 2-3 sessions/week (total: 36 sessions) of isocaloric MICET or HIIT on cycle ergometer. VO2peak and maximal aerobic power (MAP) were determined using maximal cardiopulmonary exercise test (CPET) on cycle ergometer and continuous ECG and BP were monitored every 2 min. Cardiometabolic profile (body composition, blood lipids, BP), arrhythmias (24h-holter monitoring) and left ventricular ejection fraction (LVEF) were measured before and after the intervention. MICET consisted of: 5 min of warm-up period, 37 min at 60% maximal aerobic power (MAP) and 5 min of cool down. HIIT included: 5 min of warm-up, 3 sets of 10 minutes of repeated phases of 15 sec at 100% MAP alternating with 15 sec passive recovery and 5 min of cool down. Results: Significant improvement in VO2peak (normalized by lean body mass (LBM)) was observed in the MICET group only (MICET VO2peak: 29.26±4.87 vs. 34.26 mL/min/LBM, p<0.05), but not in the HIIT group (HIIT VO2peak: 30.01±6.36 vs. 30.81±4.88 mL/min/LBM, p>0.05). No significant improvements in body composition, BP or blood parameters were observed in either group. No adverse events including no increase of ventricular arrhythmias or deterioration of LVEF were noted with HIIT (56±6 vs. 57±7%, p>0.05). Conclusion: In patients post-ACS, MICET appeared to have a greater impact on VO2peak compared to HIIT, while no improvement in cardiometabolic risk profile was observed in either group. HIIT was well tolerated and was not associated with increased ventricular arrhythmias or deterioration of cardiac function.