Usefulness of coronary fractional flow reserve measurements in guiding clinical decisions in intermediate or equivocal left main coronary stenoses.

The objectives of this study were to evaluate the usefulness of fractional flow reserve (FFR) measurements to guide the clinical decision in patients with intermediate left main coronary artery (LMCA) stenosis and to determine the predictors of major adverse cardiac events (MACE) -- cardiac death, myocardial infarction, coronary revascularization -- in such cases; 142 consecutive patients with intermediate LMCA stenosis (mean percent diameter stenosis 42 +/- 13%) were included. All patients underwent FFR measurement after intracoronary administration of adenosine at a dose > or =30 microg. The clinical decisions were based on FFR as follows: coronary revascularization was recommended if FFR was <0.75, medical treatment if FFR was >0.80, and individualized decision based on additional clinical data if FFR was between 0.75 and 0.80. Mean FFR was 0.81 +/- 0.09 after the administration of 176 +/- 99 microg of adenosine. Based on FFR results, 60 patients (42%) underwent coronary revascularization, and 82 patients (58%) received medical treatment. At 14 +/- 11 months follow-up, the incidence of MACE related to the LMCA stenosis was 13% in the medical treatment group and 7% in the revascularization group (p = 0.27). The incidence of cardiac death or myocardial infarction was 6% in the medical treatment group and 7% in the revascularization group (p = 0.70). In the medical treatment group, with MACE had received a lower dose of intracoronary adenosine (86 +/- 57 vs 167 +/- 102 microg; odds ratio 1.39 for each decrease of 30 microg of intracoronary adenosine, 95% confidence interval 1.02 to 1.89) and more frequently had diabetes (55% vs 21%; odds ratio 4.40, 95% confidence interval 1.17 to 16.42). In conclusion, FFR measurement is helpful in guiding the decision whether to revascularize patients with intermediate LMCA stenosis. However, patients with diabetes remain at higher risk, and higher doses than previously recommended of intracoronary adenosine might have to be used in the evaluation of LMCA stenosis.