Abstract 15267: A Novel Surface ECG Based Marker of Ventricular Arrhythmia in Patients with Ischaemic Cardiomyopathy
Introduction Better sudden cardiac death (SCD) risk markers are needed. Retrospective studies have shown that the Regional Restitution Instability Index (R212) is predictive of ventricular arrhythmia in ischaemic cardiomyopathy patients. The R2I2 quantifies cardiac electrical instability by measuring heterogeneity in electrical restitution. We present the first prospective evidence of R2I2's potential.
Methods Blinded prospective study of 51 ischaemic cardiomyopathy patients undergoing risk stratification for implantable cardioverter defibrillator and 15 control patients having an electrophysiological study (EPS) for assessment of supraventricular tachycardia. Action potential duration restitution gradient heterogeneity was quantitated as the R2I2 using 12 lead ECG recorded during an EPS.
Results R2I2 was significantly higher in IHD patients compared with controls (mean±SEM: 0.93±0.05vs.0.67±0.05,p=0.005) and higher in 10 patients with endpoint of appropriate ICD therapy (Ax) / death than the rest (1.21±0.12vs.0.86±0.04 p=0.002 median 15 month follow up). R2I2 was predictive of endpoint independent of EPS result, LVEF or QRS duration (Cox model p=0.004). A Kaplan Meier curve of ischaemic cardiomyopathy patients partitioned into high and low risk groups by a predefined R2I2 value of 1.03 is shown in Figure 1.
Conclusions The R2I2 appears to be able to differentiate high risk patients into those who develop ventricular arrhythmias and those at low risk. R2I2 is a straightforward, potentially non-invasive test that could add considerable value to existing sudden cardiac death risk markers.
- © 2012 by American Heart Association, Inc.