The assessment of cardiac rehabilitation's effect on echocardiographic parameters of Left Ventricular systolic function in patients treated by Primary Percutaneous Coronary Intervention due to acute ST-segment Elevation Myocardial Infarction

The aim of this study is to determine the effects of cardiac rehabilitation on echocardiographic parameters of Left Ventricular (LV) systolic function in patients treated by Primary Percutaneous Coronary Intervention (PPCI) due to acute ST-segment Elevation Myocardial Infarction (STEMI). The sample size was statistically considered to be at least fifty patients. Therefore, fifty nine patients who had inclusion criteria, were included randomly in two groups: rehabilitation (29 people) and control (30 people) after obtaining the informed written consent. Inclusion criteria: complete revascularization after PPCI and LV systolic dysfunction indicated by LV Ejection Fraction of 35-49%. Exclusion criteria: atrial fibrillation; more than mild LV hypertrophy in two-dimensional echocardiography; poor echocardiographic window; post-myocardial infarction angina; resting systolic blood pressure > 180 mmHg; resting diastolic blood pressure > 110 mmHg; symptomatic orthostatic change in systolic blood pressure > 20 mmHg; severe aortic stenosis; uncontrolled tachycardia or bradycardia; decompensated heart failure; uncontrolled diabetes mellitus; acute systemic illness; physical disability. The participants in two groups are matched for age and gender. The rehabilitation group participate in a comprehensive cardiac rehabilitation program including a supervised exercise training course, whereas the control individuals are just instructed of risk factor management. The cardiac rehabilitation program consists of 24 sessions and conducts over an 8-week period (three times per week). Each session lasts about one hour beginning with a warm-up (10 minutes) and follows by 40 minutes of aerobic exercise training using recumbent upper and lower extremity ergometers. The last 10 minutes is allocated to cool-down and all sessions finish by relaxation. The heart rate reserve is calculated on the basis of individualized resting and maximal heart rate obtained by a exercise test before the start of cardiac rehabilitation program and the target heart rate is set up between 40-60% of the reserve as exercise intensity to achieve a moderate level. For all patients who complete the whole rehabilitation program, the exercise test is repeated at the end of sessions with the same protocol as the basic one and Metabolic Equivalents (METs) are calculated before and after the cardiac rehabilitation program. During the first week after acute STEMI, a baseline two-dimentional transthoracic echocardiography including speckle tracking echocardiography is done using a vivid E9 (General Electric) system and all measurements including LV Ejectin Fraction, Fractional Shortenning, Stroke Volume and mean Global Longitudinal LV Strain, are performed by one expert echocardiologist according to the latest recommendations of American Society of Echocardiography. The echocardiography will be repeated after the completion of the cardiac rehabilitation program in the rehabilitation group and after the same period in the control group. All the follow-up examinations use the same system as basic ones and the same echocardiologist, blinded to the patient assignment group analyzes them. After the completion of course, the values of echocardiographic parameters of LV systolic function will be compared statistically within and between the two groups.

Shiraz Cardiovascular Research Center