Non-invasive markers for sudden cardiac death risk stratification in dilated cardiomyopathy

Abstract

Dilated cardiomyopathy (DCM) is a common yet challenging cardiac disease. Great strides have been made in improving DCM prognosis due to heart failure but sudden cardiac death (SCD) due to ventricular arrhythmias remains significant and challenging to predict. High-risk patients can be effectively managed with implantable cardioverter defibrillators (ICDs) but because identification of what is high risk is very limited, many patients unnecessarily experience the morbidity associated with an ICD implant and many others are not identified and have preventable mortality. Current guidelines recommend use of left ventricular ejection fraction and New York Heart Association class as the main markers of risk stratification to identify patients who would be at higher risk of SCD. However, when analysing the data from the trials that these recommendations are based on, the number of patients in whom an ICD delivers appropriate therapy is modest. In order to improve the effectiveness of therapy with an ICD, the patients who are most likely to benefit need to be identified. This review article presents the evidence behind current guideline-directed SCD risk markers and then explores new potential imaging, electrophysiological and genetic risk markers for SCD in DCM.

Fragmented QRS Pattern in Patients with COVID-19: Further Insights into Its Temporal and Mechanistic Features

“…Fragmented QRS (f-QRS) pattern has been regarded as a promising electrocardiographic (ECG) risk-stratifier in various clinical conditions including dilated cardiomyopathy, etc. 1 , 2 Pathophysiologically, this phenomenon is uniformly agreed to denote an existing myocardial injury and scar formation leading to an eventual derangement in ventricular depolarization. 1 , 2 In their recently published article, Özdemir et al 1 have documented the prognostic value of f-QRS in the prediction of all-cause mortality in patients with severe coronavirus disease 2019 (COVID-19).…”

“… 1 , 2 Pathophysiologically, this phenomenon is uniformly agreed to denote an existing myocardial injury and scar formation leading to an eventual derangement in ventricular depolarization. 1 , 2 In their recently published article, Özdemir et al 1 have documented the prognostic value of f-QRS in the prediction of all-cause mortality in patients with severe coronavirus disease 2019 (COVID-19). Within this context, we would like to make further comments on their study findings and potential implications of f-QRS in the setting of COVID-19.…”

“…First, temporal emergence of f-QRS pattern might significantly differ in patients with COVID-19: Accordingly, f-QRS might be regarded as a pre-existing (serving as a marker of underlying cardiovascular disease) or a new-onset phenomenon (emerging as a consequence of COVID-19-related factors) in these patients. In this regard, pre-existing f-QRS might be predominantly ascribed to clinical 2 or subclinical myocardial disease. However, as the authors mentioned in the section of study limitations, there were no previous ECG data of study participants.…”

“…Pathophysiologically, irreversible f-QRS is mostly associated with scar tissue formation due to myocardial injury associated with COVID-19-related factors including hyperinflammation, hypoxia, etc. 1 , 2 On the other hand, reversible f-QRS in patients with COVID-19 might possibly be attributable to transient disturbances in cardiac ion channels (leading to interruption of myocardial depolarization and possibly repolarization currents) potentially associated with the direct impact of certain cytokines on myocardium usually in the absence of scar formation. In this context, certain cytokines including tumor necrosis factor-α, etc., were previously suggested to be associated with abnormal calcium handling (with prolonged action potential durations) and sodium channel dysfunction (associated with disturbed myocardial depolarization) along with abnormalities in repolarization parameters including corrected QT interval (QTc) and transmural repolarization of myocardium).…”