Effect of a 6-week and 12-week cardiac rehabilitation program on heart rate recovery

Background: Cardiac rehabilitation has been shown to reduce cardiac mortality, improve quality of life, and reduce hospitalizations. Cardiac rehabilitation programs are usually performed over a 12-week period. Studies have shown that similar benefits could be achieved with shorter programs. Abnormal heart rate recovery after exercise has been associated with an increased risk of cardiovascular events and mortality. The main aim of this study was to compare the effect of a 6-week phase 2 cardiac rehabilitation program on heart rate recovery to a 12-week one in patients who had recovered from an anterior wall ST segment elevation myocardial infarction. Results: This prospective study included 60 patients enrolled in cardiac rehabilitation programs randomized into two equal groups: a 6-week and a 12-week program. Baseline patient demographics, lipid profile, and left ventricular ejection fraction (LVEF) were assessed. METs achieved, total exercise time, resting heart rate, peak heart rate, and heart rate recovery at 1 min were examined. These were re-assessed at the end of each program. Results showed no difference between both groups at the end of each program regarding lipid profile and LVEF. Patients enrolled in the 12-week cardiac rehabilitation program were able to achieve more METs, had a longer exercise time, a higher peak heart rate, and had a lower resting heart rate at the end of the program. Heart rate recovery was slightly higher in patients enrolled in the 6-week program 26.5 +/- 6.78 versus 23.17 +/- 6.12 bpm (p= 0.051). On comparing the magnitude of change between both programs, those in the 12-week program had more increase in HDL-C levels, METs achieved, and exercise time. Additionally, they had more reduction of resting heart rate. Heart rate recovery was more increased for those in the 6-week program. Conclusion: Although heart rate recovery increases after completion of each of a 6-week and 12-week cardiac rehabilitation program compared to their baseline, there is no difference on comparing heart rate recovery between both programs at their end. Patients enrolled in a standard 12-week cardiac rehabilitation program achieve more METs, have a longer exercise time, a higher peak HR, and a lower resting HR at the end of the program compared to those in the 6-week program.