Clin Res Cardiol (2022). https://doi.org/10.1007/s00392-022-02002-5

Late Gadolinium Enhancement Predicts ICD Indication at the Time of Generator Replacement in Patients with Primary Prevention ICD Therapy
M. Roosta Azad1, C. Karamarkou1, A. Emara1, M. Lambers1, K. Nassenstein2, O. Bruder1
1Klinik für Kardiologie und Angiologie, Elisabeth-Krankenhaus Essen GmbH, Essen; 2Inst. f. Diagnostische u. Intervent. Radiologie u. Neuroradiologie, Universitätsklinikum Essen, Essen;
Background: Implantable cardioverter-defibrillator (ICD) therapy for primary prevention of sudden cardiac death in patients with a left ventricular ejection fraction (LVEF) of 35 percent or less is supported by a strong body of prospective clinical trials and has become an essential part of guideline-based treatment of patients with heart failure. However, one quarter to one third of patients do not experience life saving ICD therapy during battery life or left ventricular function even improves above 35 percent. With increasing age and thus co-morbidities, fraility, dementia and non-cardiac mortality decision making at the time of generator exchange is more challenging and scientific evidence is limited. Late gadolinium enhancement (LGE) following contrast administration in cardiac magnetic resonance (CMR) imaging detects myocardial scar as the life-long arrhythmogenic substrate with high spatial resolution. LGE has an independent an strong prognostic impact in patients with ischemic  and non-ischemic cardiomyopathies in general and in patients scheduled for ICD therapy in particular. Objective: To investigate the potential of LGE prior to initial primary prevention CMR implant to predict an LVEF of  ≤35% at the time of generator exchange.                                                  

Methods:
Consecutive patients with an LVEF of ≤35% and optimal medical heart failure therapy underwent CMR imaging prior to ICD implantation. CMR was performed at 1.5 Tesla scanners (Sonata / Avanto, Siemens Medical Solution, Erlangen) using steady-free-precession sequences for ventricular volumetry and function and inversion recovery sequences after gadolinium contrast administration for tissue characterization as described previously. The extent of LGE was expressed as  percent of left ventricular mass. A subendocardial pattern of LGE was defined as ischemic, and the absence of LGE or an intramural or subepicardial pattern of LGE was defined as non-ischemic. LVEF before generator exchange was calculated from transthoracic echocardiography in four chamber orientation by using Simpson´s method.  A multivariate model was used to  assess the impact of LGE before initial ICD implantation on LVEF at the time of generator exchange.                          

Results:
100 patients (28 women, 62±11 years) with a LVEF of 24±7% were enrolled. LGE was present in 66 (66%) patients. The extent of LGE was 16±20% of LV mass. An ischemic pattern of LGE was diagnosed in  42 (42%) patients, and a non-ischemic pattern in 58 (58%) patients. Generator exchange was performed after 6±2 years. LVEF at that time was 40±12%. LVEF was > 35% in 70 (70%) patients and ≤35% in 30 (30%) patients. Using a multivariate model including age and gender the presence of LGE at initial presentation was significantly related to an LVEF of 35% or less at the time generator exchange (OR 6.95; 95% CI (1.84-26.28)).

Conclusions:
LGE before initial ICD implantation for primary prevention of sudden cardiac death predicts LVEF ≤35% at the time of generator exchange. As LGE visualizes arrhythmogenic scar tissue and represents more advanced disease CMR may play an important role in identifying patients that benefit from ICD protection beyond the lifetime of the ICD battery.

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