Transient symptomatic episodes of AF, often responsible for impaired quality of life, are unpredictable in frequency and timing, but amenable to effective contemporary treatments, and infrequently progress to permanent AF. AF is not a major contributor to heart failure morbidity or a cause of arrhythmic sudden death; when treated, it is associated with low disease-related mortality, no different than for patients without AF. AF is an uncommon primary cause of death in HCM virtually limited to embolic stroke, supporting a low threshold for initiating anticoagulation therapy.

We describe a case of stress-induced cardiomyopathy following epoprostenol withdrawal. A patient with pulmonary arterial hypertension presented with a malfunctioning Hickman catheter. Inappropriate withdrawal of epoprostenol resulted in shock. Evaluation confirmed stress-induced cardiomyopathy. Restarting epoprostenol resolved the electrocardiographic and echocardiographic abnormalities. This case meets Taskforce on Takotsubo Syndrome Stress-Induced Cardiomyopathy criteria. ( Level of Difficulty: Beginner. )

Introduction: LBBB results in impaired transseptal conduction and delayed posterolateral LV activation. Criteria for left bundle branch block (LBBB) vary across scientific organizations. Septal myectomy for hypertrophic cardiomyopathy (HCM) could serve as an iatrogenic anatomic model to characterize LBBB. Objective: To describe ECG features of LBBB after septal myectomy for HCM. Methods: ECG data were analyzed for 377 HCM patients (204 male) who developed post-operative LBBB after extended septal myectomy between 2004-2018. Results: Average age of the cohort at myectomy was 53 ± 14 years. Baseline QRS duration (QRSd) was 94 ± 10ms. The post myectomy QRSd was 152 ± 15ms, consistent with an average ΔQRSd of 58 ± 13ms. There was positive correlation between pre and post myectomy QRSd (r = 0.485; p < 0.0001). The average LV end-diastolic diameter (LVEDd) pre and 2 months post myectomy was 40 ± 5.6mm and 46.2 ± 6.5mm, respectively. Positive correlation between post myectomy QRSd and post myectomy LVEDd was also observed (r = 0.340; p < 0.0001). Females and males had pre myectomy QRSd of 93 ± 10ms and 95 ± 10ms respectively (p = 0.007) and post myectomy QRSd of 147 ± 13ms (120-184ms) and 157 ± 14ms (126-209ms) respectively (p < 0.0001). ΔQRSd was less in females than males (54 ± 13ms vs. 62 ± 11ms; p<0.0001). Only 13 females and 3 males had post myectomy QRSd < 130ms. Only 23 males had QRSd < 140ms. Conclusions: Surgical myectomy serves as a model to characterize LBBB. Following myectomy, QRSd correlated with LVEDd as well as pre-myectomy QRSd, and was longer in males due to delayed depolarization of larger hearts in men. Notably only 3 males and a minority of females had QRSd < 130ms. These data provide important insights for the validation of electrocardiographic LBBB criteria.

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Introduction: Subcutaneous implantable cardioverter defibrillators (SICD) are an attractive option for sudden death (SCD) prevention in younger hypertrophic cardiomyopathy (HCM) patients. Conversely, SICDs have higher rate of inappropriate shock (IAS) when compared to transvenous devices. Objective: We characterize incidence of appropriate shock (AS) and IAS and analyze predictors of IAS in HCM SICD patients. Methods: Data was collected from HCM SICD patients from 2013 to 2021. We used multivariable logistic regression to assess for predictors of IAS in patients with > 6 mo follow up. Results: 94 HCM patients (age 47 ± 15 years) underwent SICD implant with mean follow up of 3.7 ± 2.0 year. Maximal LV thickness 20.5 ± 5.8 mm with massive hypertrophy (> 30 mm) in 10 patients (11.8%). Initial DFT with 65J was successful in 88 patients, with 5 more successful after device adjustment. 5 patients (5.9%) had 10 AS (3.2 AS per 100 pt-years). 10 patients (11.8%) had 19 IAS (6.0 IAS per 100 pt-years) due to T wave oversensing (n = 13), P wave oversensing (n = 2), atrial arrhythmia (n=2), and external noise (n = 1). IAS rate decreased over time, with IAS occurring in 8 patients of the initial half of the cohort and in only 2 of the second half. Time to IAS from implant was 11 ± 10.8 mo. QRS duration (OR 1.025, 95% CI 0.997-1.053; P = 0.084) showed trend to prediction of IAS, but no characteristic proved independently significant. Conclusions: This data adds to increasing evidence that in high-risk HCM patients, SICD represents a reliable treatment option for SCD prevention. IAS mainly due to cardiac oversensing, was seen in 11.8% of patients within this HCM cohort. IAS decreased over time, possibly due to improved patient selection, implant technique and device programming (SMART pass filter). A larger dataset is likely necessary to better understand this trend.