Manipulating Exercise Intensity and Affective Responses on a Cardiac Rehabiliattion Program for Patients With Acute Coronary Syndrome: Protocol for a Randomized Controlled Trial

Ischaemic heart disease remains the top global cause of death, with cases rising by 2.7 million to 9.0 million deaths over the past two decades and between 1990-2019 the percentage of years of life lived with disability increased 83%.

Ischaemic heart disease includes acute coronary syndromes (ACS) that consist of acute myocardial infarction (AMI) and unstable angina. After ACS there is a greater risk of recurrence of the event, arrhythmias, heart failure and sudden death. These patients also have a lower quality of life which impacts their physical function and psychological well-being. ACS represent a substantial direct cost and economic burden for national health systems. Prevention must be prioritized and the emphasis on encouraging physical activity (PA) and routine exercise has become more vital than ever.

The 2023 European Society of Cardiology Guidelines for the management of ACS recommend that all patients participate in a medically supervised, structured, comprehensive cardiac rehabilitation (CR) program with a multidisciplinary team. Its core components are patient assessment, management and control of cardiovascular risk factors, PA counselling, prescription of exercise training, dietary advice, tobacco counselling, patient education, psychosocial management, and vocational support. Exercise plays a key role having a Class I, Level A evidence supporting its benefits, while specific components such as aerobic PA and muscle-strengthening exercises are supported by Class I, Level B evidence. CR plays a crucial role in lowering rates of hospitalization, fatal and non-fatal myocardial infartion, while improving exercise capacity and quality of life. There is also a reduction in healthcare costs for participants in a CR program compared with nonparticipants.

CR typically consists of three phases: phase 1 (in-hospital), phase 2 (mostly in an outpatient setting: centre-based or home-based) and phase 3 (maintenance phase in outpatient or community settings, aimed at sustaining lifestyle changes). Phase 2 CR is typically provided as an outpatient program, lasting between 8 to 24 weeks, with sessions offered 3 to 7 days per week.

A progressive program of structured exercise and PA are a fundamental part of a CR program. Exercise training should be tailored to the individual, following a thorough clinical assessment that includes risk stratification, behavioral traits, personal objectives, and exercise preferences. Exercise should be prescribed based on FITT-VP (frequency, intensity, time, type of exercise, volume, and progression) model. It is recommended to do aerobic training at a frequency of at least 3 days per week, with a preference for 6-7 days per week, at a moderate or moderate-to-high intensity. It is also advised to do resistance training, 2 days per week, at 30-70% of one-repetition maximum (1RM) for the upper body and 40-80% of 1RM for the lower body, with 12-15 repetitions/set. After the end of the CR program (i.e., beginning of phase 3), ACS patients should accumulate at least 30 minutes per day, 5 days per week of moderate intensity PA (equating to 150 minutes per week) or 15 minutes per day, 5 days per week of vigorous intensity PA (equating to 75 minutes per week), or a combination of both. These PA levels are needed for reducing disease progression and increasing quality of life.