Enhanced external counterpulsation improved myocardial perfusion and coronary flow reserve in patients with chronic stable angina - Evaluation by N-13-ammonia positron emission tomography

Aims The mechanism by which enhanced external counterpulsation therapy exer ts its beneficial effects on chronic and symptomatic stable angina is large ly unknown. To clarify the mechanism of action of enhanced external counter pulsation, we used N-13-ammonia positron emission tomography to evaluate my ocardial perfusion. Methods and Results This was not a randomized controlled study. Eleven pati ents (eight male, age: 61.6 +/-9.7) with angina pectoris underwent enhanced external counterpulsation therapy for 35 1 h sessions. They underwent a tr eadmill exercise test and N-13-ammonia positron emission tomography, both a t rest and with dipyridamole; before and after enhanced external counterpul sation therapy. Neurohumoral factors and nitric oxide were also evaluated. Myocardial perfusion increased at rest after therapy (0.69 +/-0.27 to 0.85 +/-0.47 ml.min(-1).g(-1), P<0.05). In ischaemic regions, particularly the a nterior region, myocardial perfusion at rest and with dipyridamole and coro nary flow reserve improved significantly after therapy (at rest: 0.71<plus/ minus>0.26 to 0.86 +/-0.31; P<0.05, with dipyridamole: 1.26<plus/minus>0.65 to 1.84 +/-0.94; P<0.02, coronary flow reserve: 1.75<plus/minus>0.24 to 2. 08 +/-0.28; P<0.04). Exercise time was prolonged and the time to 1-mm ST de pression improved markedly (P<0.01). After therapy, nitric oxide levels inc reased (P<0.02) and neurohumoral factors decreased. Conclusions Enhanced external counterpulsation therapy improved myocardial perfusion at rest and with dipyridamole and was associated with an increase d exercise tolerance with N-13-ammonia positron emission tomography and inc reased nitric oxide levels. These results suggest that one of the enhanced external counterpulsation mechanisms is development and recruitment of coll ateral vessels. (Eur Heart J 2001; 22: 1451-1458, doi:10.1053/euhj.2000.254 5) (C) 2001 The European Society of Cardiology.