Beta-adrenergic blockade decreases coronary collateral blood flow in patients with coronary artery disease

The effect of beta-adrenergic blockade on coronary collateral blood flow has not been clarified. We examined the acute effects of beta-adrenergic blockade on coronary collateral blood flow. Fifteen patients (Part A) with stable angina were studied while undergoing coronary angioplasty. According to the protocol, all patients underwent a minimum of three balloon inflations. Collateral flow velocity was determined during balloon inflations using the Doppler flow guidewire positioned distally to the lesion. The two tested balloon inflations, the second and third, were maintained for the same length of time. Between the second and third balloon inflations, 1 mg of propranolol was administered IC into the treated artery. Ten controls were studied following saline infusion. In 10 other patients (Part B), the effect of 1 mg IC propranolol on the coronary artery area distal to the lesion was studied, and five patients served as controls. In the treated group, in Part A blood pressure remained stable during the balloon inflations tested. Heart rate decreased from 79 +/- 11 to 73 +/- 12 beats/min (P < .05), velocity time integral from 9.6 +/- 8.2 to 6.6 +/- 4.1 cm (P < .05), and ST elevation from 1.3 +/- .9 to .9 +/- 1.0 mV (P < .05) between the second and third balloon inflations. In the controls the variables examined did not change during the balloon inflations tested. In Part B, neither propranolol nor normal saline had any significant effect on coronary artery lumen area. Thus, IC administration of beta-adrenergic blockade decreases coronary collateral blood flow, and this potentially worsens the ischemic zone. However, beta-adrenergic blockade ameliorates myocardial ischemia during coronary angioplasty.