Internal mammary artery: methods of use and their effect on survival after coronary bypass surgery

Abstract

Hazard analysis of total and cardiac mortality after isolated primarycoronary artery surgery was performed using univariate and multivariatemethods with special emphasis on the importance of the use and method ofuse of the internal mammary artery (IMA) as a bypass graft. The clinicaldata of 5880 consecutive patients were studied. The sum of the realfollow-up periods studied was 27,948 years. The hazard of total and cardiacmortality 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 yearsand 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). Thecardiac 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 latephase after surgery with a very high estimate (-2.3). The generatedsimulation of the total survival of a median patient with an IMA graft is97% at 5 years and 94% at 10 years; for a median patient without an IMAgraft, it is 97% at 5 years and 88% at 10 years. If a patient has otherrisk factors reducing his life expectancy, the influence can be dissipatedbecause of lower survival rates at 5 years after surgery, when the effectof the IMA becomes most apparent.(ABSTRACT TRUNCATED AT 250 WORDS)