Trial Files: Potassium Supplementation to Prevent VT, mRNA Vaccine for Flu, and ECG Patch Monitoring to Detect Afib
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Does targeting a higher potassium prevent VT?
Increasing the Potassium Level in Patients at High Risk for Ventricular Arrhythmias
The POTCAST Trial. NEJM (Aug 2025)
Bottom Line: This multicenter, open-label, event-driven, randomized superiority trial conducted in Denmark enrolled 1200 participants at high risk for ventricular arrhythmias with an ICD and plasma potassium levels below 4.3 mmol/L. Participants were assigned to either a high-normal potassium group, which received potassium supplementation, a mineralocorticoid receptor antagonist, or both, along with dietary guidance and standard care, or a standard-care group. The primary end point was a composite of documented sustained ventricular tachycardia or appropriate ICD therapy, unplanned hospitalization for arrhythmia or heart failure, or death from any cause, assessed in a time-to-first-event analysis, over a median follow-up of 39.6 months. Results showed 136 events in the intervention group (22.7%) compared to 175 in the comparator group (29.2%), with a hazard ratio of 0.76 (hazard ratio, 0.76; 95% confidence interval, 0.61 to 0.95; P = 0.01). Overall, treatment-induced increase in plasma potassium levels led to a significantly lower risk of appropriate ICD therapy, unplanned hospitalization for arrhythmia or heart failure, or death from any cause than standard care.
Can mRNA vaccines prevent influenza?
Efficacy, Immunogenicity, and Safety of Modified mRNA Influenza Vaccine
The Pfizer C4781004 Trial. NEJM (Nov 2025)
Bottom line: This phase 3 trial evaluated the efficacy and safety of a quadrivalent modRNA influenza vaccine compared to a licensed inactivated quadrivalent influenza vaccine in 18,476 healthy adults aged 18 to 64 years in the United States, South Africa, and the Philippines. The primary outcome was the relative efficacy against laboratory-confirmed influenza associated with influenza-like illness at least 14 days post-vaccination. The relative efficacy of the modRNA vaccine as compared with the control vaccine against influenza-like illness was 34.5% (95% confidence interval [CI], 7.4 to 53.9) on the basis of 57 cases in the modRNA group and 87 cases in the control group, a finding that met the criteria for both non-inferiority and superiority. Safety assessments revealed higher rates of reactogenicity in the modRNA group, specifically in terms of overall local reactions (70.1% vs. 43.1%) and overall systemic events (65.8% vs. 48.7%).
Can a 14-day ECG patch improve detection of afib?
Remote Screening for Asymptomatic Atrial Fibrillation
The AMALFI Trial. JAMA (Aug 2025)
Bottom Line: This parallel-group, unblinded, remote randomized clinical trial evaluated the long-term efficacy of AF screening in older individuals with a CHA2DS2VASc score of 3 or higher (men) or 4 or higher (women) using 14-day ECG patch monitoring. Conducted from May 2, 2019, to February 28, 2022, with a sample size of 5,040 participants, this study compared ECG patch monitoring to usual care. The primary outcome was the proportion of participants with AF recorded in primary care records within 2.5 years, showing 6.8% in the intervention group versus 5.4% in the control group (ratio of proportions, 1.26 [95% CI, 1.02-1.57]; P = .03). Stroke occurred in 69 participants (2.7%) in the intervention group and 64 (2.5%) in the control group (rate ratio, 1.08 [95% CI, 0.76-1.53]).
Trial Files Issue #2025-26
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