Relation of delayed intrinsicoid deflection of the QRS complex to sudden cardiac death in patients with hypertrophic cardiomyopathy.

AIMS: Predictors of sudden cardiac death (SCD) in patients with hypertrophic cardiomyopathy (HCM) do not include ECG variables. Intrinsicoid deflection (ID) represents the early ventricular depolarization on surface ECG. Delayed ID (DID) has been associated with sudden cardiac arrest (SCA) in the community. In a cohort of consecutive patients with HCM, we assessed whether DID predicts SCA or its surrogates. METHODS: We reviewed ECG, clinical and follow-up data of 344 consecutive HCM patients. DID (ID ≥50 ms) was classified as lateral (leads I or aVL), inferior (leads II, III or aVF), and precordial (leads V5 or V6). The endpoint was a combination of SCD, resuscitated SCA or appropriate ICD intervention. RESULTS: The SCA group was composed by 2 secondary prevention ICD recipients and 23 patients that reached the endpoint during follow-up (108 ± 73 months). SCA patients had more frequently massive LV hypertrophy (LVH) or end-stage HCM. ECG indexes of LVH were comparable between SCA and controls. SCA patients were more likely to have DID on ECG lateral leads I/aVL (72% vs 44%; p = 0.008). A non significant trend was observed for inferior and V5/V6 leads. DID I/aVL was associated with SCA in multivariate analysis after correction for massive LVH and end-stage disease (HR: 2.86; 95%CI: 1.14-7.13; p = 0.02). CONCLUSIONS: In HCM patients DID is associated with increased risk of SCA. Its prognostic value extends beyond that of LVH. If confirmed in prospective studies, the prognostic power of this ECG marker could be used to refine risk prediction.

Novel Imaging and Genetic Risk Markers in Takotsubo Syndrome.

Takotsubo syndrome (TTS) is an increasingly recognized condition burdened by significant acute and long-term adverse events. The availability of novel techniques expanded the knowledge on TTS and allowed a more accurate risk-stratification, potentially guiding clinical management. The present review aims to summarize the recent advances in TTS prognostic evaluation with a specific focus on novel imaging and genetic markers. Parametric deformation analysis by speckle-tracking echocardiography, as well as tissue characterization by cardiac magnetic resonance imaging T1 and T2 mapping techniques, currently appear the most clinically valuable applications. Notwithstanding, computed tomography and nuclear imaging studies provided limited but promising data. A genetic predisposition to TTS has been hypothesized, though available evidence is still not sufficient. Although a genetic predisposition appears likely, further studies are needed to fully characterize the genetic background of TTS, in order to identify genetic markers that could assist in predicting disease recurrences and help in familial screening.

Prevention of Sudden Cardiac Death: Focus on the Subcutaneous Implantable Cardioverter-Defibrillator.

The implantable cardioverter-defibrillator (ICD) is the most effective therapy to prevent sudden cardiac death (SCD) in high-risk patients. To overcome infections and failure of transvenous leads, the most frightening complications of conventional ICDs, a completely subcutaneous ICD (S-ICD) has been developed and is currently adopted in routine clinical practice. In view of their long life-expectancy, low competitive risk of dying from non-arrhythmic causes, and high lifetime risk of lead-related complications requiring surgical revisions, young patients with cardiomyopathies and inherited arrhythmia syndromes have traditionally been considered ideal candidates for the S-ICD. However, as growing evidence supported S-ICD safety and efficacy, initial niche implant indications were abandoned in favor of a widespread use of this technology, that is currently adopted in common ICD candidates with severe left ventricular dysfunction. Indeed, guidelines recommend S-ICD implantation as an alternative to TV-ICDs in all ICD candidates, unless pacing is required. This review focuses on the contemporary experience with the S-ICD and explores future scenarios in which device-to-device communication will enable to combine leadless therapies.

Assessing Atrial Fibrillation Substrates by P Wave Analysis: A Comprehensive Review.

Atrial fibrillation (AF) is the most common cardiac arrhythmia. Pharmacologic and non-pharmacologic rhythm control strategies impact on AF-related symptoms, while leaving largely unaffected the risk of stroke. Moreover, up to 20% of AF patients are asymptomatic during paroxysmal relapses of arrhythmia, thus underlying the need for early markers to identify at-risk patients and prevent cerebrovascular accidents. Indeed, non-invasive assessment of pre-clinical substrate changes that predispose to AF could provide early identification of at-risk patients and allow for tailored care paths. ECG-derived P wave analysis is a simple-to-use and inexpensive tool that has been successfully employed to detect AF-associated structural and functional atrial changes. Beyond standard electrocardiographic techniques, high resolution signal averaged electrocardiography (SAECG), by recording microvolt amplitude atrial signals, allows more accurate analysis of the P wave and possibly AF risk stratification. This review focuses on the evidence that support P wave analysis to assess AF substrates, predict arrhythmia relapses and guide rhythm-control interventions.