Coronary artery thrombosis and thrombolysis in baboons: the effect of atenolol treatment on myocardial infarct size.

The effect of the beta-blocker atenolol on experimental infarct size was studied in a non-human primate model. In 12 baboons thrombosis of the left anterior descending coronary artery (LAD) was induced and atenolol (0.1 to 0.2 mg.kg-1 intravenously, sufficient to lower the heart rate by 20%) was administered 10 min after the onset of ischaemia in six animals, whereas the others received placebo. Thrombolysis was induced 60 min after the onset of ischaemia by intravenous injection of rtPA (12 micrograms.kg-1.min-1) in all animals. Heart rate dropped significantly after atenolol injection (128 +/- 9 beats.min-1 versus 163 +/- 15 beats.min-1, P less than 0.001) and was also lower than in the control group (128 +/- 9 beats.min-1 versus 158 +/- 22 beats.min-1, P less than 0.05). Blood pressure remained unchanged after atenolol treatment. As compared to the control group, atenolol limited infarct size, expressed as a percentage of left ventricular mass (4.6 +/- 1.9% versus 7.9 +/- 1.3%, P less than 0.05) or as a percentage of the perfusion area (26 +/- 8% versus 43 +/- 8%, P less than 0.05).