Introduction: Diabetes Mellitus is associated with increased mortality from coronary artery disease. 
Cardiac rehabilitation (CR) is an evidence-based form of secondary prevention and is well-established 
in the effective management of patients with acute coronary syndrome (ACS). The heart rate is an
important prognostic factor of cardiovascular diseases. Heart rate recovery (HRR) is a strong 
independent mortality predictor in patients with previous myocardial infarction (MI). Aim: To study 
the effect of exercise based cardiac rehabilitation program on HRR in diabetic patients with ST 
segment elevation myocardial infarction (STEMI) post successful primary percutaneous coronary 
intervention (1ry PCI). Methods: Fifty diabetic patients, who presented with STEMI started CR 
program at Ain Shams cardiac rehabilitation unit 30 days post successful primary PCI after 
myocardial infarction. Before CR program they were subjected to a symptom limited exercise test 
(modified Bruce protocol) to exclude any remaining ischemia and calculate enrollment resting heart 
rate (HR), maximum HR, HR reserve, baseline HR recovery in 1st minute (HRR1) and 2nd minute 
(HRR2) into recovery. Another symptom limited exercise test was done after completion of the CR 
program. In order not to affect the results of the study, patients on beta blockers or other rate-reducing 
drugs, anti-hypertensive drugs, lipid lowering drugs and anti-diabetic drugs continued using the same 
doses during the study period. Results: There was statistically significant increase in HR reserve 
from 53.7±10.5 bpm to 64.1 ±11.8 bpm as well as significant increase in HRR1 and HRR2 from 12.3 
±2.8 bpm & 23.1± 6.45 bpm to 24.4 ±4.3 bpm & 39.1±4.7 bpm respectively after completion of the 
CR program (P-value<0.01). Conclusions: We conclude that in post MI diabetic patients treated by 
1ry PCI, exercise based CR program improves the HR recovery which may have a positive prognostic 
effect on morbidity and mortality