Predictors of sudden cardiac death in atrial fibrillation: The Atherosclerosis Risk in Communities (ARIC) study

P Wave Parameters and Indices: A Critical Appraisal of Clinical Utility, Challenges, and Future Research-A Consensus Document Endorsed by the International Society of Electrocardiology and the International Society for Holter and Noninvasive Electrocardiology

Atrial cardiomyopathy, characterized by abnormalities in atrial structure and function, is associated with increased risk of adverse cardiovascular and neurocognitive outcomes, independent of atrial fibrillation. There exists a critical unmet need for a clinical tool that is cost-effective, easy to use, and that can diagnose atrial cardiomyopathy. P wave parameters (PWPs) reflect underlying atrial structure, size, and electrical activation; alterations in these factors manifest as abnormalities in PWPs that can be readily ascertained from a standard 12-lead ECG and potentially be used to aid clinical decision-making. PWPs include P wave duration, interatrial block, P wave terminal force in V₁, P wave axis, P wave voltage, P wave area, and P wave dispersion. PWPs can be combined to yield an index (P wave index), such as the morphology-voltage-P-wave duration ECG risk score. Abnormal PWPs have been shown in population-based cohort studies to be independently associated with higher risks of atrial fibrillation, ischemic stroke, sudden cardiac death, and dementia. Additionally, PWPs, either individually or in combination (as a P wave index), have been reported to enhance prediction of atrial fibrillation or ischemic stroke. To facilitate translation of PWPs to routine clinical practice, additional work is needed to standardize measurement of PWPs (eg, via semiautomated or automated measurement), confirm their reliability and predictive value, leverage novel approaches (eg, wavelet analysis of P waves and machine learning algorithms), and finally, define the risk-benefit ratio of specific interventions in high-risk individuals. Our ultimate goal is to repurpose the ubiquitous 12-lead ECG to advance the study, diagnosis, and treatment of atrial cardiomyopathy, thus overcoming critical challenges in prevention of cardiovascular disease and dementia.

VENTRIСULAR ECTOPIC ACTIVITY - A PREDICTOR OF SUDDEN CARDIAC DEATH IN PATIENTS WITH ATRIAL FIBRILLATION AND POST-INFARCTION LEFT VENTRICULAR ANEURISMS

The article presents a clinical case of a patient who died suddenly from a rapid transformation of ventricular extrasystole into high-grade ectopy during persistent atrial fibrillation. All electrical events preceding death were recorded by the Holter monitor, which the patient was wearing at the time. It was revealed that post-infarction left ventricular aneurysm can be specified as the main predictor of sudden cardiac death, given that the myocardial scar tissue is an arrhyth¬mogenic substrate of pathological re-entry circuits to initiate high-rate ventricular arrhythmias. Heart rate variability and heart rate turbulence, as well as frequent ventricular ectopy plays significant role in the pathological mechanisms of fatal arrhythmias. Complex cardiac arrhythmias combined with changes in the autonomic regulation of the cardiovascular system are early predictors of sudden cardiac death.

Atrial Fibrillation Is Associated with Increased Mortality in Patients Presenting with Ventricular Tachyarrhythmias

Heterogenous data about the prognostic impact of atrial fibrillation (AF) in patients with ventricular tachyarrhythmias exist. Therefore, this study evaluates this impact of AF in patients presenting with ventricular tachyarrhythmias. 1,993 consecutive patients presenting with ventricular tachyarrhythmias (i.e. ventricular tachycardia and fibrillation (VT, VF)) on admission at one institution were included (from 2002 until 2016). All medical data of index and follow-up hospitalizations were collected during the complete follow-up period for each patient. Statistics comprised univariable Kaplan-Meier and multivariable Cox regression analyses in the unmatched consecutive cohort and after propensity-score matching for harmonization. The primary prognostic endpoint was long-term all-cause mortality at 2.5 years. AF was present in 31% of patients presenting with index ventricular tachyarrhythmias on admission (70% paroxysmal, 9% persistent, 21% permanent). VT was more common (67% versus 59%; p = 0.001) than VF (33% versus 41%; p = 0.001) in AF compared to non-AF patients. Long-term all-cause mortality at 2.5 years occurred more often in AF compared to non-AF patients (mortality rates 40% versus 24%, log rank p = 0.001; HR = 1.825; 95% CI 1.548–2.153; p = 0.001), which may be attributed to higher rates of all-cause mortality at 30 days, in-hospital mortality and mortality after discharge (p < 0.05) (secondary endpoints). Mortality differences were observed irrespective of index ventricular tachyarrhythmia (VT or VF), LV dysfunction or presence of an ICD. In conclusion, this study identifies AF as an independent predictor of death in patients presenting consecutively with ventricular tachyarrhythmias.

P Wave Indices-Advancing Our Understanding of Atrial Fibrillation-Related Cardiovascular Outcomes

Atrial fibrillation (AF) is associated with an increased risk of ischemic stroke, heart failure, cognitive decline, dementia, myocardial infarction, sudden cardiac death (SCD), and all-cause death. Although these associations are firmly established, our understanding of the underlying mechanisms remains incomplete. Accumulating evidence suggests that left atrial (LA) abnormality or atrial cardiomyopathy may explain the relationship of AF to the aforementioned outcomes. P-wave indices (PWIs) reflect underlying atrial remodeling. In this mini review, we define representative PWIs, discuss state-of-the-art knowledge on the relationship between abnormal PWIs and AF-related cardiovascular outcomes (focusing on ischemic stroke and sudden cardiac death), and propose directions for future research. Our ultimate goal is to present a practical way forward to advance the emerging field of LA abnormality or atrial cardiomyopathy.