Impaired ventricular electrical stability and sympathetic hyperactivity in patients with multivessel coronary artery disease

OBJECTIVES: The extent of atherosclerotic disease is identified as one of the most important predictors of long-term cardiac events in patients with coronary artery disease. Heart rate variability and QT dynamicity have been used as independent predictors for sudden death in coronary artery disease. Heart rate variability and QT dynamicity, however, have never been investigated in multivessel coronary artery disease. The aim of this study was to identify autonomic nervous system activity and ventricular vulnerability in multivessel coronary artery disease. METHODS: We examined 204 patients who underwent coronary angiography. According to the number of the three major coronary vessels with significant stenosis (>70%), we divided the patients into three groups: normal coronary arteries (n=61), single-vessel coronary artery disease (n=53) and the multivessel coronary artery disease (n=90). Twenty-four-hour ambulatory electrocardiographic recording was performed by a three-channel recorder. Heart rate variability and QT dynamicity parameters were obtained by ELA TEC software. RESULTS: Baseline characteristics were similar in multivessel coronary artery disease, single-vessel coronary artery disease and controls. SDNN (90±35, 117±52, 134±53, respectively; P<0.001) and HFnu (9.6±8.2, 8.9±3.7, 12.2±7.4, respectively; P=0.011) were significantly lower, whereas LFnu (27.2±11.3, 26.1±8.4, 22.0±13.4, respectively; P=0.014) and LF/HF ratio (4.4±3.2, 3.3±1.4, 2.1±1.6, respectively; P<0.001) were significantly higher in multivessel coronary artery disease. QTend/RR and QTapex/RR slopes were more significantly increased in multivessel coronary artery disease than in single-vessel coronary artery disease and control participants [QTend/RR: 0.15 (0.04-0.66), 0.12 (0.02-0.33), 0.12 (0.01-0.22), respectively; P=0.002; QTapex/RR: 0.16 (0.06-0.30), 0.12 (0.02-0.29), 0.11 (0.01-0.19), respectively; P<0.001]. CONCLUSIONS: Heart rate variability and QT dynamicity are impaired in patients with multivessel coronary artery disease. Our results may indicate that heart rate variability and QT dynamicity parameters can be useful noninvasive methods that may detect autonomic nervous system activity and ventricular vulnerability in multivessel coronary artery disease.