Chronic bradycardia stimulates the formation of collateral vessels in patients with coronary artery disease, a small retrospective study has found.
Patel and colleagues at Georgetown University reviewed angiographic and electrocardiographic records of 61 patients with high grade obstructive coronary artery atherosclerosis (>70% stenosis). Patients were divided into a study group (heart rate ≤50 beats/min) and a matched control group (heart rate ≥60 beats/min) and graded according to the extent of collateral development. A significantly greater proportion of patients in the study group was found to have developed collaterals (97% versus 55% in the control group; p<0.005), the authors report. In addition, the average collateral grade was higher in the study group than in the control group, with average grades of 1.66 and 0.95, respectively. Calculation of odds ratios confirmed that bradycardic patients had more collateral vessel growth than their colleagues with a faster heart rate.
The researchers conclude that slower heart rates encourage the growth of coronary collateral vessels in patients with coronary artery disease. If this finding is verified, drugs that induce bradycardia could potentially be important in treating patients with atherosclerosis, Patel's team note.