INTERNAL MAMMARY ARTERY - METHODS OF USE AND THEIR EFFECT ON SURVIVAL AFTER CORONARY-BYPASS SURGERY

Hazard analysis of total and cardiac mortality after isolated primary coronary artery surgery was performed using univariate and multivariate methods with special emphasis on the importance of the use and method of use of the internal mammary artery (IMA) as a bypass graft. The clinical data of 5880 consecutive patients were studied. The sum of the real follow-up periods studied was 27 948 years. The hazard of total and cardiac mortality could be defined in three-phase parametric models with an early, a constant and a late phase. The total survival was 82% ± 1% at 10 years and 59% ± 3.6% at 15 years. The construction of a single IMA distal graft (using left or right IMA) had a positive influence on the hazard (P = 0.0004) in the late phase after surgery with a high estimate (-1.6). The cardiac survival was 89% ± 0.8% at 10 years and 74% ± 3.5% at 15 years. The use of the left IMA had a positive influence (P = 0.001) in the late phase after surgery with a very high estimate (-2.3). The generated simulation of the total survival of a median patient with an IMA graft is 97% at 5 years and 94% at 10 years; for a median patient without an IMA graft, it is 97% at 5 years and 88% at 10 years. If a patient has other risk factors reducing his life expectancy, the influence can be dissipated because of lower survival rates at 5 years after surgery, when the effect of the IMA becomes most apparent. No additional benefit or risk, in the analysis of death after surgery, could be found in the use of sequential or double IMA grafts. © Springer-Verlag 1990.