Fractional flow reserve assessment to determine the indications for myocardial revascularisation in patients with borderline stenosis of the left main coronary artery.

INTRODUCTION Reliable assessment of clinical significance of borderline angiographic lesions found within the left main coronary artery (LM) is often impossible. Measurement of fractional flow reserve (FFR) is commonly used to verify borderline stenoses of the coronary arteries. However, the usefulness of FFR measurements has been validated only for arteries other than the LM. AIM Evaluation of the measured FFR value in determination of the indications for myocardial revascularisation in borderline LM stenosis. METHODS The study involved 38 patients aged 55+/-9 years (range 41-74 years) with isolated borderline LM stenosis. Each patient had the measurement of FFR performed during intravenous adenosine infusion at a dose of 140 microg/kg/min. Patients were referred for revascularisation if FFR was <0.75. RESULTS The mean LM stenosis in quantitative coronary angiography (QCA) was 45+/-10%. FFR<0.75 was found in 18 (47%) patients, whereas 20 (53%) subjects had FFR < or =0.75. In subjects with FFR <0.75 QCA showed significantly lower minimal lumen diameters (MLD) at the site of stenosis (1.84+/-0.45 vs 2.24+/-0.49, p=0.014). Additionally, a significant correlation was found between FFR and MLD (r=0.59, p<0.001). The mean clinical follow-up was 2 years (range 1-3 years). There were two (11%) fatal events in patients with FFR < or =0.75 who underwent CABG. One (5%) patient with FFR >0.75 underwent elective CABG due to progression of LMN stenosis. Moreover, one (5%) patient experienced myocardial infarction not related to borderline stenosis of the LM. CONCLUSIONS The measurement of FFR confirms the clinical significance of stenosis only in half of the patients with borderline isolated lesion of the left main coronary artery. Withdrawal from intervention in patients with FFR > or =0.75 is safe and is associated with favourable clinical outcomes in two-year follow-up.