Prognostic significance of coronary flow velocity reserve in patients with peripheral arterial disease.

Background: Patients with lower extremity peripheral arterial disease (PAD) have a higher risk of cardiovascular events. Stress echocardiography (SE) based on regional wall motion abnormality (RWMA) is imperfect for risk stratification in PAD, but it can be complemented with an assessment of coronary flow velocity reserve (CFVR) in the mid-distal left anterior descending coronary artery.

Objective: To assess the value of SE with RWMA and CFVR to predict survival in PAD.

Methods: In a retrospective analysis of prospectively acquired data in an observational, multicenter study, we recruited 359 patients (age 69 ± 8 years, 240 [67%] males) with PAD referred for dipyridamole SE in 3 accredited laboratories. We assessed RWMA and CFVR (abnormal value ≤ 2.0). All patients were followed up for a median of 4.7 (interquartile range: 2.0 to 8.2 years). All-cause death was the outcome end-point.

Results: The positivity rate was 37/359 (10%) for RWMA and 159/359 (44%) for CFVR. During follow-up, 97 (27%) deaths were registered. At multivariable analysis, inducible RWMA and/or CFVR ≤ 2.0 (HR 2.58, 95% CI 1.65-4.04; p < 0.0001), age ≥ 70 years, diabetes, dialysis treatment, and ejection fraction ≤ 50% were associated with decreased survival. The annual mortality was 7.4% in patients with RWMA and/or CFVR ≤ 2.0 and 2.7% in those with no RWMA and CFVR > 2.0 (p < 0.0001).

Conclusion: In patients with PAD, SE shows more than 4-fold higher prevalence of abnormal CFVR compared to RWMA. The prognostic value of CFVR outperforms RWMA, showing the importance of coronary microvascular dysfunction and diffuse, subcritical coronary atherosclerosis in determining the outcome.