Internal thoracic artery grafts: 20-year clinical follow-up

This study compared the long-term clinical results of coronary artery bypass surgery in patients with internal thoracic artery grafts with those in patients with vein grafts only.

Aortocoronary artery bypass surgery has been performed for > 25 years, primarily utilizing the saphenous vein and internal thoracic artery as conduits. Although the internal thoracic artery has been shown to confer a clinical advantage, it is not known for how many years this benefit will continue.

All consecutive patients undergoing initial coronary artery bypass surgery between 1970 and 1973 were followed for up to 20 years. Clinical evaluation included survival, late myocardial infarction, need for reoperation and recurrence of angina. Patients were analyzed in three groups: vein grafts only (214 patients); a single internal thoracic artery graft with or without associated vein grafts (490 patients); and bilateral internal thoracic artery grafts (39 patients). Use of the operating microscope was also analyzed with regard to effect on survival.

The internal thoracic artery graft and use of the operating microscope were independent predictors of mortality and reduced the risk of dying by a factor of 0.68 and 0.76, respectively. An internal thoracic artery graft resulted in a mean survival of 4.4 years longer than that with vein grafts alone. The internal thoracic artery graft compared with vein grafts was associated with fewer reoperations (p < 0.001), fewer late myocardial infarctions, lower associated mortality rates (p < 0.04) and less early recurrence of angina (p = 0.03).

The internal thoracic artery graft and use of the operating microscope confer a superior clinical advantage over the saphenous vein graft throughout a 20-year follow-up period. The advantage of an internal thoracic artery graft does not decrease with time, suggesting that the choice of conduit at the initial operation is more important clinically than progression of coronary artery disease.