Prognostic value of transthoracic coronary flow reserve in medically treated patients with proximal left anterior descending artery stenosis of intermediate severity.

Aims: Prognostic value of transthoracic coronary flow reserve (T-CFR) is not established in patients with left anterior descending artery (LAD) stenosis of intermediate severity. Objective is to determine the prognosis value of T-CFR>2 in medically treated patients with angiographically intermediate [50-70% QCA (quantitative coronary angiography)] proximal LAD stenosis.
Methods and Results: Among 110 consecutive patients with intermediate LAD stenosis who underwent prospectively T-CFR in the distal part of the LAD after intravenous administration of adenosine to assess the functional significance of the stenosis, 80 patients had T-CFR>2 and were treated medically without revascularization (Group 1). Among the 30 patients who had T-CFR<2, an additional dobutamine stress echocardiography (DSE) was performed: 15 had a negative DSE; were treated medically and served as a comparative group (Group 2), and 15 had a positive DSE; underwent LAD revascularization, and were excluded from further analysis. All patients completed follow-up (16+/-10 months). During the follow-up period (range 6-45 months), 76 patients (95%) remained free of death or LAD-related event in Group 1, vs. 12 patients (80%) in Group 2. By Kaplan-Meier method, at 30 months the per cent estimated survival free from death or target vessel-related events was 92+/-4% in Group 1 and 44+/-22% in Group 2 (P<0.01). By multivariate analysis, T-CFR remained the only independent predictor of death or LAD-related events.
Conclusion: In patients with proximal LAD stenosis of intermediate severity and T-CFR>2, deferral of revascularization is associated with low event rate.