“Left main equivalent” coronary artery disease: Its clinical presentation and prognostic significance with nonsurgical therapy

The clinical characteristics and nonsurgical prognosis of 55 patients with “left main (LM) equivalent” coronary artery disease (CAD) were evaluated and defined as: (1) ≥75% diameter reduction of the left anterior descending coronary artery (LAD) before the takeoff of any large septal perforator or anterolateral (diagonal) branches; (2) ≥75% diameter reduction of the left circumflex artery (LC) before the takeoff of any large marginal branch; and (3) absence of ≥50% stenosis of the LM coronary artery. Compared with nonsurgically treated patients with ≥75% stenosis of the LM artery, patients with LM equivalent CAD had a shorter duration of symptoms (median of 51 months vs 66 months) and more often had a Q wave on the electrocardiogram (60 vs 39 % ). Survival in patients with LM equivalent CAD (78% at 1 year and 55% at 5 years) was better than that in patients with LM disease with nonsurgical therapy (65% at 1 year and 40% at 5 years) (p = 0.02), although the rate of freedom from cardiovascular events was not significantly different. Compared with other nonsurgically treated patients with 2- or 3-vessel CAD involving the LAD and LC (28 and 42%, respectively, with progressive angina), patients with LM equivalent CAD had more severe anginal symptoms (55% with progressive angina) and a longer duration of symptoms (medians of 20 months in 2-vessel CAD, 36 months in 3-vessel CAD and 51 months in LM equivalent CAD). In patients without LM disease, the presence of LM equivalent CAD was a significant univariable prognostic factor (chi-square = 7.1, p = 0.008), but the presence of concomitant right coronary stenosis was a more powerful prognostic factor (chi-square = 16.6, p < 0.0001). In multivariable analysis the state of the left ventricular function, the anginal symptoms, and the presence of extracardiac vascular disease were more closely related to survival than the specific cardiac anatomy. The ratio of fatal to nonfatal cardiac events in follow-up was 12:1 in LM disease, 5:1 in LM equivalent CAD, 2.8:1 in 3-vessel non-LM equivalent CAD and 1.7:1 in 2-vessel non-LM equivalent CAD. These results support the concept that the likelihood of a cardiac event is related to the number of lesions at risk of occlusion, whereas the likelihood that a cardiac event will be fatal is related to the amount of myocardium distal to the occlusion.