New research was presented at Heart Rhythm 2021, the hybrid annual meeting of the Heart Rhythm Society, held virtually starting June 30 and in person from July 28-31, in Boston. The features below highlight some of the studies that emerged from the conference.

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Oral Contraceptives in Women With Congenital Long QT Syndrome

To evaluate the association of oral contraceptives (OC) with the risk of cardiac events (CE) in women with congenital long QT syndrome (LQTS), researchers obtained information on menarche onset, OC use, pregnancy, and menopause from women enrolled in the Rochester LQTS Registry. Type of OC was categorized as progestin-only, estrogen-only, or combined (estrogen/progestin). Andersen-Gill multivariate modeling was employed to evaluate the association of time-dependent OC use with the burden of CE (total number of syncope, aborted cardiac arrest, and LQTS-related sudden cardiac death) from menarche onset through age 40. Findings were adjusted for genotype, QTc duration, and time-dependent beta-blocker therapy. A total of 1,659 women with LQTS were followed through March 2021, of whom 370 (22%) were treated with an OC. During a cumulative follow-up of 35,797 years, the study team observed a total of 2,027 CEs. Multivariate analysis showed that progestin-only OC was associated with a pronounced 2.8-fold increased risk of CE among women who did not receive beta-blocker therapy, while beta-blockers were highly protective during progestin-only OC treatment (HR=0.22). Risk associated with OC use without concomitant beta-blocker treatment was pronounced in LQT2 women. They suggest that progestin-only OC not be administered in women with LQTS without concomitant beta-blocker therapy and that OC be used with caution in women with LQTS.

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Early Rhythm Control in Patients With HF & Afib

To determine if additional treatments are needed to reduce cardiovascular (CV) complications in patients with heart failure (HF) and atrial fibrillation (Afib)—especially in those with HF and preserved left ventricular ejection fraction (HFpEF)—investigators conducted a sub-analysis of the randomized EAST-AFNET 4 trial. They investigated the effects of systematic early rhythm control therapy (ERC; using antiarrhythmic drugs or catheter ablation) compared with usual care (UC, allowing rhythm control therapy to improve symptoms) in patients with HF, defined as HF symptoms NYHA II-III or left ventricular ejection fraction (LVEF) less than 50%. The analysis included 798 patients, 785 with known LVEF. Most patients had HFpEF (LVEF ≥50%; mean LVEF 61% ± 6.3%); others had HF with mid-range ejection fraction (LVEF 40-49%; mean LVEF 44% ± 2.9%) or HF with reduced ejection fraction (LVEF <40%; mean LVEF 31% ± 5.5%). During the 5.1-year median follow-up, the composite primary outcome of CV death, stroke, or hospitalization for worsening of HF or for acute coronary syndrome occurred less often in patients randomized to ERC (94/396; 5.7 per 100 patient-years) compared with patients randomized to UC (130/402; 7.9 per 100 patient-years; HR, 0.74 [0.56-0.97]) not altered by HF status. The primary safety outcome (death, stroke, or serious adverse events related to rhythm control therapy) occurred in 71/396 (17.9%) of patients with HF randomized to ERC and in 87/402 (21.6%) patients with HF randomized to UC (HR 0.85 [0.62-1.17]). LVEF improved in both groups (LVEF change at 2 years: ERC 5.3%±11.6%, UC 4.9%±11.6%). ERC also improved the composite outcome of death or hospitalization for worsening of HF.

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Post-CABG Spinal Stimulation Helps Prevent AF in High-Risk Patients?

To assess if temporary spinal stimulation after coronary artery bypass graft (CABG) surgery for patients with a history of paroxysmal atrial fibrillation (AF) reduced postoperative arrhythmia, researchers included 52 patients with at least three AF episodes of up to 7 days each in the 6 months before enrollment. Participants were randomized to on-pump CABG alone or with spinal cord stimulation for 3 days prior to the procedure and 7 days after. Both groups also took beta-blockers for at least 30 days after surgery. Continuous external ECG recordings continued after hospitalization with an ECG monitoring patch to 30 days post-op. Spinal stimulation reduced the 30-day occurrence of any AF or any atrial tachyarrhythmia lasting at least 30 seconds by a relative 89%, to just 3.8%, compared with 30.2% among usual care patients. AF burden on ECG patch monitoring was also lower. The primary safety endpoint (30-day composite rate of death, cerebrovascular accident, myocardial infarction, or kidney or spinal cord injury) was similar between groups, with the only incidents being one case of bleeding requiring transfusion or reoperation and one case of prolonged ventilation. “This novel approach could represent a new paradigm for Afib prevention and requires further investigations,” the study authors concluded.

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Left Bundle Branch Vs Right Ventricular Pacing

To compare outcomes in left bundle branch (LBB)-area pacing with right ventricular (RV) pacing in patients with bradycardia, a two-health system study assessed 321 patients who underwent LBB-area pacing and 382 who underwent RV pacing. The LBB group had more atrial fibrillation (46.1% vs 38.0%), more beta-blocker use (73.8% vs 64.2%), more single-chamber permanent pacemaker implantation (5.3% vs 0.5%), shorter-paced QRS intervals (121 vs 155 ms), longer procedures (98 vs 72 minutes), longer fluoroscopy times (13 vs 6 minutes), and more ventricular pacing burdens greater than 20% and greater than 40% (73% vs 57% and 71% vs 51%).  LBB-area pacing led to better outcomes than RV pacing in patients with bradycardia. LBB pacing was associated with a relative 54% lower likelihood of death, heart failure hospitalization, or upgrade to biventricular pacing during follow-up of at least 6 months (10% vs 23.3%). Differences were significant for all-cause mortality (7.8% with LBB pacing vs 15% with RV pacing) and heart failure hospitalization (3.7% vs 10.5%, respectively) and were most substantial among those with higher ventricular pacing burdens. Among patients with 20% or greater ventricular pacing burden who underwent LBB pacing, relative reductions were 68% for the primary endpoint, 65% for all-cause mortality, and 61% for heart failure hospitalizations.

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Comparing Cardiac Patch Monitors

Researchers performed a head-to-head comparison of the diagnostic accuracy of two commonly used cardiac monitor patch devices. The two monitors selected for the real-world, simultaneous-wear study are among the most used in the United States: Bardy Diagnostics’ Carnation long-term ECG device and Preventice Solutions’ BodyGuardian mobile cardiac telemetry device. Among 46 patients, the Carnation long-term ECG device detected arrhythmia in twice as many patients as did the BodyGuardian device during overlapping use (50% vs 24%). The Carnation ECG device also picked up substantially more events (61 vs 19). The BodyGuardian device picked up only one event that the other did not, a case of ventricular tachycardia. While there are several differences between the two devices that could account for the findings, a key feature is how data are read, according to researchers: The BodyGuardian device puts the data through algorithm-based detection with human interpretation for arrhythmias that are captured, while the Carnation device has humans read and interpret the strip initially, followed by supplementation with an algorithm. “Not all monitors are created equal,” a study author said. “We all know that computers aren’t quite as good as human beings, yet we rely on them a lot in the outpatient world.”