To the Editor - Are we close to a major impact on prevention of sudden cardiac death among coronary artery disease patients?

We read with great interest the article from Hooks and colleagues showing that ventricular tachycardia (VT) or ventricular fibrillation (VF) was the initial rhythm in ∼50% of the in-hospital cardiac arrests among patients with heart failure and preserved ejection fraction—indeed, confirming that VT/VF is a significant mechanism of sudden cardiac death (SCD) leading to a major proportion of cardiac mortality in patients with heart failure and preserved ejection fraction. In a recent autopsy study of 5869 SCD victims in the Fingesture registry in Finland, the majority of patients had evidence of myocardial scaring on autopsy, although they had no known clinical history of coronary artery disease (CAD) prior to the cardiac arrest. It is remarkable that a significant proportion of them (42.5%) had autopsy evidence of a remote silent myocardial infarction (MI). It is presumed that the unrecognized presence of MI scarring predisposed these CAD patients to malignant ventricular arrhythmias probably related to the presence of triggering factors such as myocardial ischemia developing during physical exercise. In this context we recently demonstrated that a definite high-risk post-MI group exists, even among those suffering from a limited MI without significant left ventricular systolic dysfunction and symptoms of heart failure. Furthermore, after using a combined 2-step, multifactorial electrophysiology study–inclusive approach, incorporating noninvasive electrocardiographic factors leading to programmed ventricular stimulation, we were able to protect these high-risk post-MI individuals from major arrhythmic events with an implantable cardioverter-defibrillator. The Finnish study further supports the concept that even an unrecognized, presumably limited myocardial scar may predispose a significant number of CAD patients to SCD. It is quite interesting that a significant number of those unrecognized CAD patients had electrocardiographic evidence of abnormality, pointing to the presence of myocardial scarring. Is it really time for the next step for a risk stratification approach beyond that based on left ventricular ejection fraction estimation, in order to achieve a truly significant impact on the epidemic of SCD?