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Interatrial block (IAB) is an electrocardiographic pattern describing the conduction delay between the right and left atria. IAB is classified into 3 degrees of block that correspond to decreasing conduction in the region of Bachmann's bundle. Although initially considered benign in nature, specific subsets of IAB have been associated with atrial arrhythmias, elevated thromboembolic stroke risk, cognitive impairment, and mortality. As the pathophysiologic relationships between IAB and stroke are reinforced, investigation has now turned to the potential benefit of early detection, atrial imaging, cardiovascular risk factor modification, antiarrhythmic pharmacotherapy, and stroke prevention with oral anticoagulation. This review provides a contemporary overview of the epidemiology, pathophysiology, diagnosis, and management of IAB, with a focus on future directions. (C) 2022 by the American College of Cardiology Foundation.

Abnormal heart rate turbulence (HRT) has been documented as a strong predictor of total mortality and sudden death in postinfarction patients, but data in patients with congestive heart failure (CHF) are limited.The aim of this study was to evaluate the prognostic significance of HRT for predicting mortality in CHF patients in New York Heart Association (NYHA) class II-III.In 651 CHF patients with sinus rhythm enrolled into the MUSIC (Muerte Subita en Insuficiencia Cardiaca) study, the standard HRT parameters turbulence onset (TO) and slope (TS), as well as HRT categories, were assessed for predicting total mortality and sudden death.HRT was analyzable in 607 patients, mean age 63 years (434 male), 50% of ischemic etiology. During a median follow up of 44 months, 129 patients died, 52 from sudden death. Abnormal TS and HRT category 2 (HRT2) were independently associated with increased all-cause mortality (HR: 2.10, CI: 1.41 to 3.12, P.001 and HR: 2.52, CI: 1.56 to 4.05, P.001; respectively), sudden death (HR: 2.25, CI: 1.13 to 4.46, P = .021 for HRT2), and death due to heart failure progression (HR: 4.11, CI: 1.84 to 9.19, P.001 for HRT2) after adjustment for clinical covariates in multivariate analysis. The prognostic value of TS for predicting total mortality was similar in various groups dichotomized by age, gender, NYHA class, left ventricular ejection fraction, and CHF etiology. TS was found to be predictive for total mortality only in patients with QRS120 ms.HRT is a potent risk predictor for both heart failure and arrhythmic death in patients with class II and III CHF.

A randomized trial was conducted to assess the efficacy of amiodarone versus metropolol or no antiarrhythmic treatment to suppress asymptomatic ectopic activity and improve survival in patients who have had myocardial infarction with a left ventricular ejection fraction of 20 to 45% and ≥3 ventricular premature complexes per hour (pairs or runs). Patients (n = 368) were randomly assigned to receive amiodarone 200 mg/day (n = 115) 10 to 60 days after the acute episode, and metoprolol 100 to 200 mg/day (n = 130) or no antiarrhythmic therapy (n = 123). After a median follow-up of 2.8 years, mortality in the amiodarone-treated patients (3.5 ± 2% SEM) did not differ significantly from that of untreated control subjects (7.7 ± 2.5%, p = 0.19), but was lower than that in the metoprolol group (15.4 ± 3.5%, p = 0.006). Patients treated with metoprolol had twice the mortality seen in control subjects, even though the differences were not statistically significant. Hotter studies performed at 1, 6 and 12 months showed that both amiodarone and metoprolol were equally effective in reducing heart rate, whereas only amiodarone significantly reduced ectopic activity (p

The European Society of Cardiology and American College of Cardiology established their initial Joint Consensus Conference in July 1999 to develop a new definition of Acute Myocardial Infarction. This action was deemed necessary because of the development of new sensitive biochemical markers of myocardial necroses: Troponins T and I. There were 5 working groups, including one in Electrocardiography. The Conference adopted a definition that required only a history of "ischemic symptoms" and "a typical rise and fall" of at least one of the biochemical markers. The ECG Working Group strongly advised that a term distinctive from "myocardial infarction" such as "myocardial necrosette" be adopted as the diagnosis for an acute coronary event during which the peak biochemical marker level is below that which occurs when serial evolutionary ECG changes are observed. A pilot substudy from the GUSTO IIa Clinical Trial has identified the low end of the "ECG Change Range" to be: >2x the upper limit of normal for CK-MB, > 11 x for Troponin T, and >6 x for Troponin I.

Background Repolarization lability precedes ventricular arrhythmias. However, in recent competing risk analysis QT variability index predicted non–sudden cardiac death (SCD) but did not predict SCD. Predictive values of other repolarization lability parameters have not been studied in competing risk analysis. Methods We analyzed 3 minutes of baseline resting orthogonal ECGs in sinus rhythm in 533 participants of the observational cohort heart failure (HF) study (mean age 63.1 ± 11.7; males 70.6%; left ventricular ejection fraction [LVEF] >35% in 254 [48%]). Repolarization lability was measured as the root mean square successive difference (rMSSD) of the area under the curve from T-peak to T-end series (TpTe Area rMSSD). Holter monitoring was performed to identify patients who presented frequent (>240 in 24 hours) ventricular premature beats and also nonsustained ventricular tachycardia (NSVT). SCD and non-SCD served as primary endpoints. Results During median follow-up of 3.7 years of, 116 patients died, 52 from SCD and 53 from non-SCD. In multivariate competing risk analyses after adjustment for EF, New York Heart Association HF class, NSVT, and frequent premature ventricular complexes on 24-hours Holter ECG, the highest Tpeak-Tend Area rMSSD quartile was associated with SCD [subhazard ratio: 1.79 (95% CI 1.05–3.06), P = .034] but did not predict non-SCD [subhazard ratio: 0.95 (95% CI 0.53-1.72), P = .875; Figure 1). No interaction between Tpeak-Tend Area rMSSD and LVEF was found. Conclusions Increased repolarization lability measured as Tpeak-Tend area variability predicts SCD but not non-SCD in HF across the continuum of LV dysfunction.