Scaring Myocardial Scars

Abstract

Despite the impressive development of medical therapies for patients with myocardial dysfunction, sudden cardiac death (SCD) is still too frequent. In patients with severe cardiomyopathies the insertion of an implantable cardiac defibrillator (ICD) has been shown to reduce SCD risk (1). For primary prevention in patients with left ventricular ejection fraction (LVEF) below 35%, ICD is now recommended (2). However, only 30% to 50% of implanted patients received appropriate ICD firings, and up to 25% suffered from side effects in the first year after ICD insertion (3,4). In addition, because of steadily growing demand for ICD replacements (5), the financial burden of primary ICD insertion on our healthcare systems is increasing. Consequently, there is an urgent need to improve the benefit-risk ratio of ICD insertion. See page 408The assessment of myocardial scarring with delayed enhanced cardiac magnetic resonance (DE-CMR) has become an important and independent prognostic factor of cardiovascular outcomes in various cardiomyopathies (6). It is now established that myocardial scar and/or its correlates (scar pattern, relative size, heterogenous scar periphery size, transmurality) by DE-CMR are independent prognostic markers of cardiac death or ventricular tachycardia (VT) occurrence in patients with ischemic (7-12), nonischemic (13,14), and hypertrophic cardiomyopathies (15,16) as well as in patients referred for ICD insertion (8,17). Simple myocardial scar assessment by DE-CMR is an accurate, reproducible, and reliable tool when put in trained hands. Therefore it could be reasonably integrated in addition to the precise measurement of LVEF by cardiac magnetic resonance imaging (MRI) (another advantage of cardiac MRI) in the therapeutic management of candidates for ICD insertion. With this in mind, the original article by Klem et al. (18) in this issue of the Journal is a cornerstone for the constitution of clinical trials integrating myocardial scar assessment by DE-CMR in the decision for ICD insertion.In a prospective single-center cohort study on 137 patients referred for ICD insertion, Klem et al. (18) performed an expert and simple cardiac MRI study assessing myocardial scar and LVEF before implantation. The mean LVEF was 35 Ϯ 18%, and 75% (n ϭ 104) of the patients had an ICD placed, with an indication of primary prevention in 88%. Of the entire patient population, 78% (n ϭ 107) had scar by DE-CMR, while at the same time 76% (n ϭ 105) underwent an electrophysiology study with VT induction in 20% (n ϭ 21).At 24 months, the primary endpoint occurred in 28% (n ϭ 39) of the patients with an approximately equal distribution of events between death and ICD discharge. Importantly, there were no patients lost to follow-up. The striking finding in this study is that there was a 5-fold increase in the rate of adverse events for a scar size Ͼ5% of the left ventricular (LV) mass and that scar size dichotomized approximately 5% of the LV mass provided a significant increment in prognostic value in addition to that of LVE...

Highlights of the Year in JACC 2012

“…The authors concluded that myocardial scarring detected by CMR is an independent predictor of adverse outcomes in patients being considered for ICD placement. The study results were further discussed by Mewton and Chevalier (152). …”

ECG-Based Multiclass Arrhythmia Classification Using Beat-Level Fusion Network

“…Take the STTC as an example. Te ST segment myocardial infarction (STEMI) is refected in ST elevation [46]. ST elevation is linked to infarction and can be preceded by changes indicating ischemia, such as ST depression or the T waves inversion, according to [47].…”