Electrophysiologic testing guided risk stratification approach for sudden cardiac death beyond the left ventricular ejection fraction

Abstract

Sudden cardiac death threats ischaemic and dilated cardiomyopathy patients. Anti- arrhythmic protection may be provided to these patients with implanted cardiac defibrillators (ICD), after an efficient risk stratification approach. The proposed risk stratifier of an impaired left ventricular ejection fraction has limited sensitivity meaning that a significant number of victims will remain undetectable by this risk stratification approach because they have a preserved left ventricular systolic function. Current risk stratification strategies focus on combinations of non invasive methods like T wave alternans, late potentials, heart rate turbulence, deceleration capacity and others, with invasive methods like the electrophysiologic study. In the presence of an electrically impaired substrate with formed post myocardial infarction fibrotic zones, programmed ventricular stimulation provides important prognostic information for the selection of the patients expected to benefit from an ICD implantation, while due to its high negative predictive value, patients at low risk level may also be detected. Clustering evidence from different research groups and electrophysiologic labs support an electrophysiologic testing guided risk stratification approach for sudden cardiac death.

Keywords: Electrophysiologic study, Risk stratification, Sudden cardiac death, Myocardial infarction, Preserved ejection fraction

Core tip: There is a growing need for more effective risk stratification approach in order to detect those post myocardial infarction and dilated cardiomyopathy patients at high risk for sudden cardiac death (SCD) at early or even asymptomatic stage of heart failure with relatively well preserved left ventricular ejection fraction (LVEF). Although in an individual basis the SCD risk is lower among the patient population compared to the one observed among to those with a severely impaired LVEF, epidemiologically there is a large such patient pool at risk in the community. Based on preliminary evidence these patients could be effectively and timely identified by applying a combined electrophysiologic guided approach using non-invasive electrocardiogram-related markers of risk leading to programmed ventricular stimulation testing. Using this approach, we could select those with inducible ventricular tachyarrhythmias as suitable candidates for implantable defibrillator therapy.