Improving the appropriateness of sudden arrhythmic death primary prevention by implantable cardioverter-defibrillator therapy in patients with low left ventricular ejection fraction. Point of view

Abstract

It is generally accepted that the current guidelines for the primary prevention of sudden arrhythmic death, which are based on ejection fraction, do not allow the optimal selection of patients with low left ventricular ejection fraction of ischemic and nonischemic etiology for implantation of a cardioverter-defibrillator. Ejection fraction alone is limited in both sensitivity and specificity. An analysis of the risk of sudden arrhythmic death with a combination of multiple tests (ejection fraction associated with one or more arrhythmic risk markers) could partially compensate for these limitations. We propose a polyparametric approach for defining the risk of sudden arrhythmic death using ejection fraction in combination with other clinical and arrhythmic risk markers (i.e. late gadolinium enhancement cardiac magnetic resonance, T-wave alternans, programmed ventricular stimulation, autonomic tone, and genetic testing) that have been validated in nonrandomized trials. In this article, we examine these approaches to identify three subsets of patients who cannot be comprehensively assessed by the current guidelines: patients with ejection fraction of 35% or less and a relatively low risk of sudden arrhythmic death despite the ejection fraction value; patients with ejection fraction of 35% or less and high competitive risk of death due to evolution of heart failure or noncardiac causes; and patients with ejection fraction between 35 and 45% with relatively high risk of sudden arrhythmic death despite the ejection fraction value.

A brief overview of cardiac resynchronization therapy and its current use in clinical practice

“…Moreover, excess mortality in patients who did not receive defibrillators was related to sudden cardiac death in 8% of those with ischaemic disease but in only 0.4% of those with dilated cardiomyopathy . As perspicaciously Wayne Levy pointed out in a recent editorial, we still lack good criteria for candidacy of a patient for ICD, namely we lack the ability to grade the individual arrhythmic risk (not the risk of all‐cause mortality) . While looking for more sensitive and specific criteria, the aetiology may be of some help, as well as age and gender .…”

Heart Rate Turbulence Is a Powerful Predictor of Cardiac Death and Ventricular Arrhythmias in Postmyocardial Infarction and Heart Failure Patients

“…4 By contrast, several patients who are at risk of SCD are not identified by the EF marker because the main part of SCD patients exhibits just mildly depressed EF. 5 Therefore, in recent years, efforts have been made to identify new markers or combinations of markers, 6 to improve the prognostic stratification of SCD.…”

Cardiac magnetic resonance imaging: Which information is useful for the arrhythmologist?

“…However, it is now well-known that ejection fraction alone has limited sensitivity and specificity as a risk marker for SCD, because it is not able to distinguish the risk of sudden death from death caused by heart failure or other non-cardiac diseases. Subsequently, many patients implanted for primary prevention according to current guidelines will have little benefit from their ICD, with a low rate of appropriate ICD therapy (2%-4%/year)[ 9 ], while they can suffer from side effects (even > 10%/year overall), in particular inappropriate shocks, lead failure and infections[ 10 , 11 ]. On the other side, many patients who are at risk of SCD are missed when using only LVEF, because the largest part of sudden arrhythmic death patients have only mildly depressed ejection fraction[ 9 , 12 , 13 ].…”

“…Anyway, the substrates of SCD are particularly complex, so it is unlikely for a single test to achieve significantly better predictive accuracy than LVEF. To overcome this limitation, a combination of markers has been proposed[ 9 ], for example, combining ejection fraction with different tests that investigate different arrhythmic mechanisms (LGE-CMR, T-wave alternans, programmed ventricular stimulation, evaluation of autonomic tone, etc .).…”