Background: Exercise-based rehabilitation is an important part of treatment patients following acute myocardial infarction (MI). However, data are scarce on the efffects of very short-term exercise programs in patients with acute MI treated with primary percutaneous coronary intervention (pPCI). The aim of the study was to evaluate the effects of very short-term exercise training on cardiopulmonary exercise testing (CPET) parameters in patients suffering acute MI treated with pPCI. Methods: We studied 40 consecutive patients with MI treated with pPCI reffered for rehabilitation to our institution. The study population consisted of 39 men and 1 women (age 50,60±8,40 years, left ventricular ejection fraction 53,05±6,74 %), who participated in 3-week clinical cardiac rehabilitation program. The program consisted of cycling for 7 times/week, and daily walking for 45 min at intensity of 70-80% of the individual maximal heart rate. All patients performed symptom-limited CPET on a bicycle ergometer with a ramp protocol of 10w/min. The CPET also performed after cardiac rehabilitation programs. Results: After 3 weeks of exercise-based cardiac rehabilitation program improved exercise tolerance as compared to baseline (peak workload 111,50±15,07 vs 129,00±12,77 watts, respectively, p<0,001), as well as peak respiratory exchage ratio (1,02±0,10 vs 1,08 ± 0,13, respectively, p<0,05). Peak systolic blood pressure, heart rate, peak and after 1 minute of rest were also improved. Most importantly, peak VO2 (18,17±3,30 vs 20,64±3,27 ml/kg/min, respectively, p<0,001), peak VCO2 (1,65±0,28 vs 1,96±0,25 ml/kg/min, respectively, p<0,001), peak ventilation (48,61±10,70 vs 57,27±9,85 L/min, respectively, p<0,001) and peak oxygen pulse (14,16±2,62 vs 60.18±14.19 ml/ beat, respectively, p<0,05) were also improved. No major adverse cardiac events were noted during the rehabilitation program. Conclusion: Very short-term exercise training in patients with acute MI treated with pPCI is safe and improves functional capacity, as well as test duration, work load and heart rate response. cardiac pulmonary exercise testing, exercise training, cardiac rehabilitation, myocardial infarction AbstractKey Words