Safety of deferring angioplasty in patients with normal coronary flow velocity reserve

Background. In the catheter laboratory there is need for functional tests validating the hemodynamic significance of coronary artery stenosis. Objectives. It was the objective of our study to compare the long-term cardiac event rate and the clinical symptoms in patients with reduced coronary flow velocity reserve (CFVR) and standard PTC with patients with normal CFVR and deferred angioplasty. Methods. Our study included 70 patients with intermediate coronary artery stenoses (13 f, 57 m; diameter stenosis >50%, <90%) and an indication for PTC due to stable angin pectoris and/or signs of ischemi in noninvasive stress tests. CFVR was measured distal to the lesion after intracoronary administration of adenosine using 0.014 inch Doppler-tipped guide wires. Results. In 22 patients (31%), PTC was deferred due to CFVR ≥ 2.0 (non-PTC group). In the remaining 48 patients (69%) mean CFVR of 1.4 ± 0.23 (p < 0.001) was measured (PTC group). CFVR increased to 2.0 ± 0.51 after angioplasty. During follow-up (average 15 ± 6.0 months), the following major adverse cardiac events (MACE) occurred: in the PTC group re-PTC was performed in nine patients (18.8%) because of unstable angina, five patients (10.4%) suffered an acute myocardial infarction (MI) (two infarctions occurred during the angioplasty, three patients suffered an infarction during follow-up), two patients (4.2%) needed blood transfusions due to severe bleedings, two patients (4.2%) underwent bypass surgery and one patient (2.1%) died. In the non-PTC group, angioplasty was necessary only in two cases (9.1%) during follow-up. We did not observe any MI in the non-PTC group. The overall rate of MACE was significantly lower in the non-PTC group compared to the PTC group (9.1% vs. 33.3%, p < 0.01). However, only 40% of the patients of the non-PTC group were free of angin pectoris at stress. In the PTC group, 63% did not complain of any symptoms at follow-up (p < 0.05). Conclusions. We conclude that determination of the CFVR is valuable parameter for stratifying the hemodynamic significance of coronary artery stenosis. PTC can safely be deferred in patients with significant coronary stenosis but CFVR ≥ 2.0. The total rate of MACE at follow-up was below 10% among these patients. However, if PTC was deferred the number of patients who are free of angin is lower compared to those patients who underwent angioplasty.