Study objectives: Sinus node deceleration during exercise is a highly specific marker for significant stenosis of the right coronary artery. Prior studies of dobutamine-induced sinus node deceleration have contained relatively few patients, and the purpose of this study was to determine if sinus node deceleration is an accurate marker of right coronary artery disease in a much larger study population.
Design: Dobutamine stress echocardiography was performed in a cohort of patients, and submaximal exercise testing and coronary angiography were performed in most of the patients.
Setting: A university hospital.
Patients and interventions: Dobutamine stress echocardiography was performed in 757 patients, and symptom-limited submaximal treadmill ECG was also performed in 571 of those patients. Sinus node deceleration was defined as a decrease in the heart rate at peak stress compared with that at the previous stage. Coronary angiography was performed in 631 patients, 184 of whom were found to have significant right coronary artery stenosis.
Measurements and results: The prevalence of dobutamine-induced sinus node deceleration (54 [7%] of 757 patients) was significantly higher than that induced during treadmill ECG (3 [0.5%] of 571 patients; p<0.001). The prevalence of inferior ischemia by echocardiography did not differ between patients with dobutamine-induced sinus node deceleration (26%) and those without (30%). There was also no significant difference in the prevalence of right coronary artery stenosis between the two groups (27% vs 29%). The specificity of dobutamine-induced sinus node deceleration for detecting significant stenosis of the right coronary artery (92%) was higher than that of echocardiography (84%; p<0.001), but the positive predictive value was lower (28% vs 64%; p<0.001).
Conclusions: Although sinus node deceleration during dobutamine stress echocardiography is a relatively more common finding, it does not always accompany significant stenosis in the right coronary artery. The mechanism for its induction is postulated to be vagal activation caused by multiple factors.