Effect of coronary surgery on survival in asymptomatic and minimally symptomatic patients.

The effect of aortocoronary saphenous bypass graft surgery on survival of functional class I and II patients was studied in 619 patients entered in the Seattle Heart Watch when they had coronary arteriography. Cox's regression analysis was used to correct for differences in baseline characteristics that occur as a result of nonrandom assignment to medical or surgical therapy. For the 619 patients, surgical therapy was predictive of improved survival, with bordeline statistical significance (Z = -1.820; p = 0.069). With subgroup analysis, patients with three-vessel disease had a significantly improved survival rate (Z = -2.378; p = 0.017), but patients with one-vessel disease (Z = 0.307; p = 0.758) or two-vessel disease (Z = -0.98; p = 0.324) did not.