[Decrease in left ventricular stroke performance following bypass of a significant main coronary artery stenoses].

Hemodynamic parameters and left ventricular function were assessed 14 +/- 4 (means +/- SEM) days preoperatively and 101 +/- 5 days after aortocoronary bypass surgery in eight men (51-65 years of age) with left main coronary stenosis (greater than or equal to 75%). Working capacity on bicycle exercise stress test increased from 43 +/- 7 to 68 +/- 7% of age-, and body-surface matched normals; at the same time cardiac output (thermodilution) decreased from 5.7 +/- 0.5 to 4.7 +/- 2 l/min (p less than 0.05), stroke volume decreased from 78 +/- 6 to 63 +/- 3 ml (p less than 0.01), stroke work from 1.16 +/- 0.10 to 0.89 +/- 0.07 Joule (p less than 0.001), and stroke power from 4.0 +/- 0.3 to 3.4 +/- 0.2 Joule/s (p less than 0.01) postoperatively. Left ventricular volumes decreased postoperatively but not significantly, ejection fraction remained unchanged (57 +/- 13/59 +/- 13%). A control group (PTCA of LAD) showed no significant changes of these parameters. As all patients had a good postoperative result, decrease of stroke work after aortocoronary bypass surgery is not necessarily an expression of postoperative deterioration, since it can coincide with good left ventricular function, angiographically successful revascularization, and an increase in working capacity.