Angiographically silent left main disease detected by intravascular ultrasound: A marker for future adverse cardiac events

Background: Concomitant moderate obstructive left main (LM) disease is associated with future cardiac events and poor prognosis in patients undergoing percutaneous intervention (PCI). Whether prognosis is similarly effected by LM disease not detected by angiography, but evident on intravascular ultrasound (IVUS) imaging, is not known. The purpose of this study was to evaluate the long-term prognosis of patients with angiographically insignificant LM coronary artery disease undergoing PCI. Methods and Results: One hundred and seven consecutive patients undergoing PCI with angiographically normal or mild LM disease had 2- and 3-dimensional IVUS imaging. IVUS images were digitized, and 3-dimensional reconstruction was performed. Percent diameter and area stenosis by angiography were 4.8% ± 3.5% and 18.2% ± 9.8%, respectively. IVUS mean luminal area and area stenosis were 17.9 ± 5.6 mm² and 30.2% ± 14.7%, respectively. Long-term follow-up was available in 102 (95%) patients at a median of 29 (range 8-52) months. Major adverse cardiac events, defined as death (6), myocardial infarction (4), repeat PCI (13), or CABG (16), were associated with female sex (P = .04), diabetes (P = .02), angiographic minimum lumen diameter (P = .04), and IVUS minimum (P = .01) and mean (P = .01) lumen area. Multivariate predictors of late cardiac events were diabetes (hazard ratio 2.69, P = .014) and minimum lumen area by IVUS (hazard ratio 0.59, P = .015). Conclusions: Despite being angiographically silent, LM disease detected by IVUS is an independent predictor of cardiac events and may serve as a marker for such events. These data extend the spectrum of LM disease severity and its relationship to cardiac prognosis in patients undergoing PCI.