Abstract 16337: A Risk Score That Predicts Recurrence of Neurally Mediated Syncope Using Electrocardiographic and Vectorcardiographic Parameters

Abstract

Introduction: We have previously demonstrated that isolated very low QRS voltage (VLV defined as ≤0.3mV) in the frontal leads on the electrocardiogram (ECG; Figure A), as well as flat QRS loops in the frontal plane on ECG-derived vectorcardiograms (VCG; Figure B) predict recurrence of neurally mediated syncope (NMS). This phenomenon is possibly related to a specific ventricular geometry and activation pattern. Hypothesis: The aim of this study was to attempt to incorporate these novel ECG and VCG risk factors for recurrence of syncope into a prognostic risk score. Methods: We included 215 patients (age 48±20years), with NMS and a median of 3 syncopal episodes. The patients were followed for a median of 10 months (IQR 4-20). To weigh the relative importance of the prognostic risk factors identified in multivariate Cox regression analysis we attributed a score of 1 point for HR 1.5-1.99, 2 points for HR 2.0-2.49, and 3 points for HR ≥ 2.5. The total risk score, was divided into three categories: low risk (0-2), intermediate risk (3-5) and high risk (≥6). Results: The multivariate analysis identified history of ≥ 2 syncopal events (HR 3.85, 95%CI 1.62-9.14), left ventricular end-diastolic diameter of < 39mm by echocardiography (HR 1.94, 95%CI 1.00-3.82), isolated VLV QRS in frontal leads (HR 2.60, 95%CI 1.37-4.86) and flat QRS VCG loops in frontal plane (HR 2.23, 95%CI 1.24-3.99) as independent predictors for NMS recurrence (all P < 0.05). The actuarial total syncope recurrence rate at 1 year was 54.6% (95%CI 38.2-72.6) in the high-risk score category, 25.3% (95%CI 16.8-37.1) in the intermediate risk category, and 6.2% (95%CI 2.2-16.2) in the low-risk category (log rank test P<0.0001; Figure C). The ROC curve showed an AUC of 0.77 for the predictive value of the total risk score. Conclusions: The risk of recurrence of NMS could be stratified using a risk score that incorporates novel ECG and VCG parameters in addition to more established clinical and echocardiographic variables.