Correct assessment of the significance of left main stem lesions is of pivotal importance to the patient with coronary artery disease. On the basis of clinical and angiographic information alone, this evaluation often cannot be done reliably. Limited data suggest that coronary pressure-derived fractional flow reserve (FFR) supports decision making in equivocal left main disease.

All patients presenting to our institution between June 1999 and June 2004 with intermediate left main coronary artery disease (40%-80% diameter stenosis by angiography), or in whom left main coronary disease was suspected but could not be quantified angiographically, were included in this prospective single-center follow-up study. If FFR was <0.75 along the left main stem, surgical revascularization was recommended; if FFR was >0.80, medical treatment or percutaneous coronary intervention elsewhere in the coronary tree was chosen. If FFR was in the “gray zone,” between ≥0.75 and ≤0.80 treatment recommendation was dependent on additional individual criteria. Primary end points were freedom from death, myocardial infarction, any coronary revascularization procedure, and stroke.

Fifty-one patients (mean age 62.2 ± 9.6 years, 41 male) were included. In 27 patients (53%), coronary artery bypass surgery was performed. The remaining 24 patients (47%) were treated nonsurgically. Mean follow-up was 29 ± 16 months. Estimated survival after 4 years of follow-up was 81% among patients in the surgical group and 100% among patients in the nonsurgical group. Event-free survival was 66% in the surgical group and 69% in the nonsurgical group.

Fractional flow reserve is helpful to identify patients with intermediate left main disease in whom deferral of surgical revascularization is associated with excellent survival and low event rates.