# The Relationship between Renal Resistive Index and Complexity of Coronary Lesions in Patients with Stable Coronary Artery Diseases

## TL;DR

This study found that a non-invasive ultrasound measure of kidney blood flow, RRI, is linked to more complex coronary artery disease in stable patients.

## Contribution

RRI is identified as a novel independent predictor of complex coronary lesions in stable CAD patients.

## Key findings

- RRI was a strong independent predictor of high SYNTAX score (OR = 4.440, p = 0.010).
- An RRI cut-off of 0.655 predicted high SYNTAX score with 80% sensitivity and 73.6% specificity.
- RRI was associated with CAD complexity beyond traditional risk factors like diabetes and LDL-C.

## Abstract

The most common cause of coronary artery diseases (CAD) is
atherosclerosis. The synergy between percutaneous coronary intervention with
TAXUS™ and cardiac surgery (SYNTAX) score was used to assess
complex CAD lesions. The renal resistive index (RRI) is a Doppler ultrasound
parameter calculated to assess renal haemodynamics. The direct relationship
between CAD complexity and RRI was not yet investigated. The aim of our study was
to investigate this relationship between RRI and SYNTAX score in stable CAD
patients.

This study included 214 patients with stable CAD and
subsequent coronary angiography done at our institution. Regarding CAD
complexity, these patients were classified into 166 patients with low SYNTAX
score (SYNTAX ≤22), and 48 patients with high SYNTAX score (SYNTAX >22).
The demographic, laboratory, clinical, echocardiographic data and renal Doppler
parameters; including RRI, were recorded.

Multivariate logistic
regression analysis demonstrated that RRI (odds ratio, OR = 4.440, 95%
(confidence interval) CI: 1.418–13.903, p = 0.010) was a novel
independent predictor of high SYNTAX score in patients with stable CAD, in
addition to other traditional predictors as diabetes mellitus (OR = 4.401, 95%
CI: 1.081–17.923, p = 0.04), low-density lipoprotein cholesterol
(LDL-C) (OR = 2.957, 95% CI: 1.920–8.995,
p = 0.027), multi-vessel CAD (OR = 2.113, 95% CI: 1.241–2.280, p
= 0.001) and Gensini score (OR = 6.539, 95% CI: 1.977–21.626, p = 0.002).
Receiver operator characteristic curve analysis showed that RRI >0.655
(sensitivity of 80%, specificity of 73.6%) was the best cut-off value for predicting
high SYNTAX score.

The non-invasively measured RRI is
closely associated with high SYNTAX score in stable CAD patients.