Clozapine-induced Myocarditis: Pathophysiologic Mechanisms and Implications for Therapeutic Approaches.

Clozapine, a superior treatment for treatment-resistant schizophrenia can cause potentially life-threatening myocarditis and dilated cardiomyopathy. While the occurrence of this condition is well known, its molecular mechanisms are unclear and may be multifactorial. Putative mechanisms warrant an in-depth review not only from the perspective of toxicity but also for understanding the molecular mechanisms of the adverse cardiac effects of clozapine and the development of novel therapeutic approaches.

Hypocalcemia-Induced QT Interval Prolongation.

An 87-year-old man with a history of transcatheter aortic valve replacement, pulmonary hypertension, diastolic dysfunction with preserved systolic function, and myelofibrosis had a 12-lead ECG showed a prolonged QT interval of 508 ms with heart-rate correction placing it in the 99th percentile of the population. Reduction in the dose of furosemide and calcium supplementation increased serum calcium and shortened the QT interval. This case provides an opportunity to examine newer concepts for the understanding of the mechanisms by which hypocalcemia might induce QT prolongation.

Effectiveness of medical therapy for treatment of idiopathic frequent premature ventricular complexes.

Introduction: The relative effectiveness of medical therapy compared with a conservative approach of monitoring in patients with idiopathic frequent premature ventricular complexes (PVCs) is uncertain. We evaluated the effectiveness of medical versus conservative therapy for frequent PVCs.

Methods: Patients with frequent PVCs (≥5%) were prospectively enrolled in this cohort study between 2016 and 2020.

The Short QTc Is a Marker for the Development of Atrial Flutter and Atrial Fibrillation.

A short QT interval has been difficult to define, and there is debate whether it exists outside of an extremely small group of individuals with inherited channelopathies and whether it predicts cardiac arrhythmias. The objective was to identify cases with short QT and their consequences. Our hospital ECG database was screened for cases with a QTc based on the Bazett formula (QTcBZT) of less than 340 ms.

The utility of growth differentiation factor-15, galectin-3, and sST2 as biomarkers for the diagnosis of heart failure with preserved ejection fraction and compared to heart failure with reduced ejection fraction: a systematic review.

The objective was to evaluate the diagnosis of heart failure with preserved ejection fraction (HFpEF) using the biomarkers, growth differentiation factor-15 (GDF-15), galectin-3 (Gal-3), and soluble ST2 (sST2), and to determine whether they can differentiate HFpEF from heart failure with reduced ejection fraction (HFrEF). Medline and Embase databases were searched with the terms diastolic heart failure or HFpEF, biomarkers, and diagnosis, limited to years 2000 to 2019. There were significantly and consistently higher levels of GDF-15, Gal-3, and sST2 in HFpEF compared to no heart failure.

Assessment of QT interval in ventricular paced rhythm: Derivation of a novel formula.

Objective: The objective of the study was to determine the optimal formula to estimate QT interval adjusting for QRS prolongation during right ventricular (RV) pacing.

Methods: This observational study included individuals (n = 43) with a newly implanted permanent ventricular pacemaker, who had a narrow QRS complex before pacemaker insertion. QT interval with RV pacing was related to QT interval before pacemaker implantation.

Determination of the QT Interval in Left Bundle Branch Block: Development of a Novel Formula.

Background: Determination of the prolonged QT interval in left bundle branch block (LBBB), which should be of special concern to identify individuals at high risk of potentially fatal cardiac arrhythmia risk, has been problematic.

Methods: Electrocardiograms (ECGs) (n = 17) in intermittent LBBB were used to develop a new formula for the calculation of QTc in LBBB. This formula and 5 others were compared in a population with LBBB (n = 2610).