Renal resistive index and long-term outcome in patients with coronary artery disease

Background: The study aimed to evaluate the application of intra-renal Doppler flow indices for the prediction of major adverse cardiac and cerebrovascular events (MACCE) during 24-month follow-up in patients with coronary artery disease (CAD) subject to coronary angiography (CA). Methods: This prospective study comprised 111 consecutive patients with stable and unstable CAD (68.5% men; median age 65years), referred for CA. Ultrasonographic parameters of intra-renal blood flow in arcuate/interlobular arteries, including renal resistive index (RRI) and pulsatility index (RPI), were acquired directly before and 1h after the procedure. Endpoint of MACCE (cardiovascular death, myocardial infarction, myocardial revascularization or stroke) were recorded during 24-month follow-up. Results: MACCE occurred in 14 patients (12.6%). Patients with MACCE had more diffuse CAD reflected by Syntax score (23.6 vs.14.4 pts., p=0.02), higher platelet level (242.4 vs. 207.2x1000/mu l, p=0.01), higher rate of left main CAD (42.9% vs.5.2%, p < 0.001) and left ventricular ejection fraction < 50% (50% vs.23.7%,p=0.045). Patients with MACCE had higher pre-procedural (0.680.06 vs. 0.62 +/- 0.06, p < 0.001) and post-procedural RRI (0.72 +/- 0.06 vs.0.66 +/- 0.06, p=0.01), but comparable RPI (p=0.63 and p=0.36, respectively). Cox proportional hazards model revealed that pre-procedural RRI (OR=1.11 per 0.01; p=0.02) and left main CAD (OR=5.75, p=0.002) were the only independent predictors of MACCE occurrence. Receiver operator characteristic curve analysis revealed that preprocedural RRI > 0.645 accurately predicted the composite endpoint (AUC=0.78, p=0.001) and identified patients with impaired 24-month prognosis according to Kaplan-Meier curve (log-rank p < 0.001). Conclusions: Increased pre-procedural RRI, together with left main CAD, are associated with worse 24-month prognosis in patients with CAD referred for CA.