Enhanced external counterpulsation improved myocardial perfusion and coronary flow reserve in patients with chronic stable angina. Evaluation by13N-ammonia positron emission tomography

Abstract
Aims The mechanism by which enhanced external counterpulsation therapy exerts its beneficial effects on chronic and symptomatic stable angina is largely unknown. To clarify the mechanism of action of enhanced external counterpulsation, we used13N-ammonia positron emission tomography to evaluate myocardial perfusion. Methods and Results This was not a randomized controlled study. Eleven patients (eight male, age: 61·6±9·7) with angina pectoris underwent enhanced external counterpulsation therapy for 35 1h sessions. They underwent a treadmill exercise test and13N-ammonia positron emission tomography, both at rest and with dipyridamole, before and after enhanced external counterpulsation therapy. Neurohumoral factors and nitric oxide were also evaluated. Myocardial perfusion increased at rest after therapy (0·69±0·27 to 0·85±0·47ml.min−1.g−1,P PPPPPConclusions Enhanced external counterpulsation therapy improved myocardial perfusion at rest and with dipyridamole and was associated with an increased exercise tolerance with13N-ammonia positron emission tomography and increased nitric oxide levels. These results suggest that one of the enhanced external counterpulsation mechanisms is development and recruitment of collateral vessels.

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