Radionuclide assessment of ventricular performance during propranolol withdrawal prior to aortocoronary bypass surgery.

The effects of oral propranolol upon left ventricular performance were assessed in 18 patients with angiographically documented coronary artery disease in whom propranolol was tapered prior to elective aortocoronary bypass surgery. Left ventricular ejection fraction, ejection rate, and regional wall motion were obtained on three occasions with first-pass radionuclide angiocardiographic techniques. Patients were studied at peak propranolol dose ( +/- SEM) 224 +/- 29 mg./day; serum propranolol level, 85 +/- 22 ng./ml.), intermediate dose (99 +/- 9 mg./day; serum propranolol, 30 +/- 6 ng./ml.), and 24 hours following discontinuation of propranolol therapy. Heart rate increased significantly (62 +/- 2.3 vs 67 +/- 3.0 vs 73 +/- 2.3 beats/minute, p less than 0.001) during propranolol withdrawal, while systolic blood pressure did not change significantly (114.7 +/- 4.3 vs 110.3 +/-3.0 vs 113 +/- 3.0 mm. Hg, p greater than 0.05). There was no significant change in ejection fraction (59.1 +/- 2.4 vs 60.4 +/- 2.0 vs 59.2 +/- 2.5 per cent) or ejection rate 2.80 +/- 0.18 vs 2.87 +/- 0.18 vs 2.92 +/- 0.20 sec.-1) as propranolol was tapered (p greater than 0.05). No patient demonstrated a change in regional wall motion in response to propranolol withdrawal. The results of this study suggest that oral propranolol in commonly used clinical dosages does not significantly affect radionuclide measures of left ventricular performance in the basal state.