Risk factors of ventricular tachyarrhythmias after coronary artery bypass grafting.

BACKGROUND: Ventricular arrhythmias are rare and represent the most serious arrhythmic complication after coronary artery bypass grafting (CABG).
METHODS: The present retrospective study was conducted for identifying patients at risk of ventricular arrhythmias with ventricular signal averaged ECG, standard deviation of all normal RR intervals (SDNN), angiographic and echocardiographic data. We defined ventricular arrhythmias as sustained ventricular fibrillation and ventricular tachycardia. The study population consisted of 209 consecutive patients with sinus rhythm undergoing CABG. The primary endpoint was the occurrence of VA after CABG. The secondary endpoints were hospital length of stay after CABG and the occurrence of VA after hospital discharge.
RESULTS: During the postoperative follow-up ventricular arrhythmias were observed in 11 patients (5%). Patients with ventricular arrhythmias showed a higher incidence of ventricular late potentials (91 vs. 9% of patients, p<0.0001) than patients without ventricular arrhythmias. In addition patients with ventricular arrhythmias had a lower left ventricular ejection fraction (44.2+/-15.2 vs. 60.1+/-13.1%, p<0.0001) and a SDNN (22.4+/-8.8 vs. 34.4+/-16.1 ms, p<0.02). A stepwise logistic regression analysis of all variables identified the combination of ventricular late potentials, ejection fraction < or = 38% and SDNN < or = 28 ms (odds rate 26.00; 95% CI, 3.44-196.67, p<0.002) as an independent predictor of ventricular arrhythmias.
CONCLUSIONS: The results of our study suggest that the probability of ventricular arrhythmias could be predicted after CABG by a combination of low left ventricular ejection fraction and a measurement of ventricular signal averaged ECG and standard deviation of all normal RR intervals. Patients who can be identified as having a high risk of ventricular arrhythmias should be observed carefully after surgery.