The Effect of Cardiac Rehabilitation on Left Ventricular Remodeling in Patients Undergoing Primary Percutaneous Coronary Intervention for Acute Myocardial Infarction

ST-segment elevation myocardial infarction (STEMI) remains a leading cause of morbidity and mortality worldwide. Primary percutaneous coronary intervention (PCI) is the gold standard for reperfusion therapy in STEMI, significantly improving survival rates. However, adverse left ventricular (LV) remodeling post-STEMI can lead to heart failure, poor clinical outcomes and deterioration in patients' quality of life.

Cardiac rehabilitation (CR) is a multidisciplinary intervention designed to optimize cardiovascular recovery. It involves a spectrum of interventions including a structured exercise program, patient education, nutritional counseling, risk factor modification and psychosocial support. CR is divided into 4 stages. Stage I is in-hospital exercise (early mobilization and patient education). Stage II is early outpatient supervised rehabilitation in rehabilitation centers lasting 3 months post-PCI. Stage III starts at 3-12 months and is usually home-based rehabilitation with frequent visits to rehabilitation centers. Stage IV is long term rehab where the patient continues to exercise and commit to a healthy lifestyle to prevent further episodes of cardiovascular disease. Research has shown that stage II is the most crucial of them all, and starting during early in-hospital setting has shown no further improvement in cardiovascular health.

Exercise-based programs, have especially shown beneficial effects on LV function post-AMI, improving exercise capacity and potentially limiting adverse remodeling process. It has been reported that supervised exercise training after STEMI significantly increased LVEF and reduced the rate of unfavorable remodeling at 6 months compared to usual care.

Moreover, there was a significant reduction in post-treatment LV mass, EF, and LV dimensions relative to pretreatment. It has also been suggested that early initiation of CR may reduce systemic inflammation and promote favorable ventricular remodeling.

However, other studies have shown that CR may not have a clinically significant improvement in LV parameters despite the overall improvement in patient's exercise capacity , but these studies were performed with a small sample size. Other trials have shown mixed results, with some showing favorable remodeling after exercise therapy, and some showing no improvement in cardiac dimensions. Another study mentioned that CR may have a positive effect on LV diastolic dysfunction, without any change to LV dimensions.