Effect of atenolol (ICI 66 082) on coronary haemodynamics in man

The coronary haemodynamic effect of atenolol, a new cardioselective beta-adrenergic blocker, was studied in 15 patients with angina pectoris. Myocardial blood flow from the anterolateral part of the left ventricle was measured by the continuous infusion thermodilution method by means of a two-thermistor catheter with pacing electrodes placed in the great cardiac vein. Catheters were also positioned in the pulmonary artery and the thoracic aorta for blood sampling, pressure measurements, and cardiac output determination. Investigations were performed at rest, at slow, and at submaximal atrial pacing rates before and 10 minutes after injection of 5 mg atenolol intra-venously. Coronary angiography was performed in all patients. Atenolol reduced resting myocardial bloodflow by 16 per cent (P<0-001) and oxygen consumption by 17 per cent (P<0-001). Flow was reduced whether or not the part of myocardium in question was supplied by a stenotic artery. Coronary arteriolar resistance increased by 23 per cent (P<0 001). Myocardial arterio-venous oxygen difference was not affected. Heart rate and rate-pressure index were reduced in all patients (P<0-001). When the heart rate was kept constant by atrial pacing there was no change in the rate-pressure index and no change in any of the coronary haemodynamic values. A small but highly significant increase of 2 mmHg ± 0*4 (SEM) in left ventricularfilling pressure was observed at rest (P<0-001), and 4 mmHg ± 0