Prognostic significance of sinus deceleration during dobutamine stress echocardiography test following acute myocardial infarction

BACKGROUND/AIM: Chronotropic incompetence during exercise stress testing after acute myocardial infarction is an indicator of ischemia or impaired left ventricular function. On the other side, infusion of dobutamine leads to a typical dose-dependent increase in heart rate. The aim of this study was to evaluate of paradoxical sinus deceleration during dobutamine stress echocardiography (DSE), as the sign of ischemia and impaired left ventricular function, or the consequence of infarction localization, and the estimation of prognostic significance after acute myocardial infarction. METHODS: Our investigation comprised 81 patients hospitalized because of the acute myocardial infarction, and all of them had uncomplicated infarction. Fifty five patients were treated with thrombolytic therapy (67.9%); 53 patients (65.4%) had anterior myocardial infarction, and 28 patients (34.6%) had inferoposterior localization of myocardial infarction. After 10-12 days all of them underwent dobutamine stress echocardiography examination. During the next 3-6 months, the patients underwent coronary angiography. The average follow-up period was 36 +/- 22 months. RESULTS: A decrease in heart rate occurred at the dobutamine doses increasing from 15-40mcg/kg/min in 9 (11.1%) of the patients, in 1 patient with an anterior localization and in 8 patients with an inferoposterior localization. The decrease was sudden in 4 (44.4%), and gradual in 5 (55.6%) of the patients. In 3 patients (33.3%) junction rhythm was developed, and in 2 patients (22.2%) AV block II-III. Only in 2 of them, there was a worsening of regional function during a high dose dobutamine infusion, but 7 of them showed an improvement during a low dose. In 7 (77.8%) of the patients there was a simultaneous decrease in blood pressure. Coronary angiographic examination showed that in 4 (44.4%) of the patients there was a significant coronary artery disease and they underwent the revascularisation procedure. During the follow up period, there was not any significant arrhythmic disorder in that group of the patients or repeated hospitalization because of postinfarction angina, re-infarction, or heart failure. CONCLUSION: We could conclude that paradoxical sinus deceleration is not only an indicator of a significant coronary artery disease and "bad left ventricle". It also may occur as a consequence of vasodepressor reflex (Bezold-Jarisch), even after acute myocardial infarction, withont influencing a long-term prognosis.