Temporal trends of left ventricular function preceding sudden cardiac death

A severely reduced left ventricular ejection fraction (LVEF ≤ 35%) increases the risk of sudden cardiac death (SCD) and is considered the most important indication for medical and device therapies used to prevent SCD. The spectrum of LVEF among SCD subjects in the modern era remains unclear.

We evaluated temporal changes in LVEF over 2 decades among SCD victims with both ischemic and nonischemic etiologies.

The Finnish Genetic Study of Arrhythmic Events is a population-based study of SCD that comprises 5869 consecutive autopsy-verified SCD victims from Northern Finland between 1998 and 2017. Quantitatively assessed LVEF was obtained from electronic health records. In all cases, echocardiography was unrelated to the SCD event. The study period was divided into 5-year intervals to study temporal trends.

Pre-SCD LVEF was available for 716 SCD victims. The prevalence of severely reduced LVEF was 15.4% (110 subjects) during the entire study period and significantly decreased over the study period quartiles to one-third from baseline (30.6% during 1998-2002, 20.0% during 2003-2007, 13.5% during 2008-2012, and 10.6% during 2013-2017; P < .001, unadjusted β = -5.6% per 5 years; 95% confidence interval, -8.3% to -2.9%). The overall incidence of SCDs per capita and those with echocardiography remained essentially the same during the last 15 years.

The proportion of SCD cases with LVEF of ≤35% has significantly decreased in recent decades. Only a minority of modern-day SCD victims undergoing echocardiography are identified as being at high risk for SCD according to LVEF. Individualized risk assessment beyond LVEF measurement is needed to assess the risk of SCD.