Factors influencing patency of coronary bypass grafts
The immediate relief of angina pectoris was striking in the earliest patients treated with bypass graft surgery in the late 1960s. Early optimism was tempered, however, by the uncertainties of long-term graft patency, particularly in view of the experiences reported with autogenous venous femoropopliteal bypass grafts with which patency ranged from 20% to 90%, depending upon the site of the distal anastomosis, adequacy of runoff, and time. Early postoperative arteriograms of coronary bypass grafts in 48 patients operated upon from May 1967 through September 1968 demonstrated patency in 87.5% of grafts. Encouraged by these results, the indications for surgical treatment were cautiously expanded to include larger numbers of patients.
Patients are selected for bypass graft surgery on the basis of angiographic assessment of their coronary arteries and left ventricle. In many instances, the arteriographic assessment of an artery is supplanted by that of the surgeon at the time of operation, and the various factors influencing graft patency are preempted by these preselection criteria. It is recognized that the greater likelihood of symptomatic patients with graft failure to return for postoperative study introduces a negative bias into postoperative arteriographic results. This can be overcome only by 100% arteriographic follow-up of survivors or by strict randomization of patients for postoperative arteriography, neither of which has been achieved. Al-though a large number of patients have returned for routine postoperative studies 1 year or more after surgery, an increasing caseload in the Cardiac Catheterization Laboratory has precluded the routine 1 year postoperative study, and . . .