Effects of digitalis on resting and isometric exercise myocardial perfusion in patients with coronary artery disease...

Digitalis has been shown to improve the impaired ventricular function associated with coronary artery disease as well as to increase myocardial oxygen consumption and produce coronary vasoconstriction. To elucidate the net result of these contrasting effects, six patients with coronary artery disease and left ventricular ejection fractions less than 0.50 had 1.0 mCi thallium-201 injected intravenously at rest and during three minutes of 33% of maximal handgrip, off and on 0.25 mg daily maintenance digoxin. Thallium-201 scintigram images were taken 30 minutes later and were computer processed with orthogonal linearly interpolated background subtraction and maximal count density equalization. Processed images were visually graded on a 0, 1, or 2 scale for 18 sectors--nine from the AP projections and nine from the 40 degrees left anterior oblique projections. A score resulting from the summation of the 18 sector grades was made for each study, the maximum score being 36. Off digitalis, patients performing handgrip exercise decreased their scintigram scores from 25.7 +/- 1.5 (mean +/- SEM) to 23.0 +/- 1.0, P less than 0.05. When patients were on maintenance digoxin, scores did not change significantly during handgrip exercise. Post exercise scores were significantly higher on digoxin than off (P less than 0.05), whereas, resting scores were unaffected by digoxin. These data suggest that myocardial perfusion, as measured by thallium-201 uptake, is improved in patients on digitalis who have coronary artery disease and left ventricular dysfunction.