Arrhythmic risk stratification in heart failure: Time for the next step?

Abstract

Background: Primary prevention of sudden cardiac death by means of implantable cardioverter-defibrillators constitutes the holy grail of arrhythmology. However, current risk stratification algorithms lead to suboptimal outcomes, by both allocating ICDs to patients not deriving any meaningful survival benefit and withholding them from those erroneously considered as low-risk for arrhythmic mortality.

Methods: In the present review article we will attempt to present shortcomings of contemporary guidelines regarding sudden death prevention in ischemic and dilated cardiomyopathy patients and present available data suggesting encouraging results following implementation of multifactorial approaches, by using multiple modalities, both noninvasive and invasive. Invasive electrophysiological testing, namely programmed ventricular stimulation, will be discussed in greater length to highlight both its potential usefulness and currently ongoing multicenter studies aiming to provide evidence necessary to make the next step in sudden death risk stratification.

Results: Promising findings have been reported by multiple study groups regarding novel strategies for both negative selection of low and positive selection of relatively preserved ejection fraction patients as candidates for ICD implantation.

Conclusions: The era of ejection fraction as the sole risk stratifier for arrhythmic risk in heart failure appears to be drawing to an end, especially if current underway large studies validate previous findings.

Keywords: multifactorial approach; primary prevention; programmed ventricular stimulation; risk stratification; sudden cardiac death.

Figure 1

Emerging new sudden cardiac death risk stratification paradigm based on newer evidence, incorporating competing mortality assessment, as well as noninvasive and invasive tests. Noninvasive tests are performed before PVS to assess likelihood for functional circuit formation. PVS is pivotal in determining the potential for arrhythmia sustenance and guide treatment, especially in intermediate‐ and low‐risk patients. “Observe and Follow‐up” involves repeating tests for NIRF annually and PVS every 3–5 years. NIRF = noninvasive ECG risk factors, including presence of late potentials (≥2/3 criteria), frequent premature ventricular contractions (≥30/hr), nonsustained VT (≥1/24 hr), abnormal heart rate turbulence (onset ≥0% and slope≤2.5 ms), positive T wave alternans (≥65 μV), reduced deceleration capacity (≤4.5 ms), decreased heart rate variability (SDNN<70 ms), prolonged QT _c interval (>460 ms in males and >480 ms in females)