Synthetic Cooling Chemicals in E-Cigarettes Disrupt Cardiac Rhythm in 2026 Circulation Study

The research exposed Langendorff-perfused rabbit hearts to WS-23 and other cooling agents at 1-10 micromolar, levels previously measured in user aerosol by FDA labs. Researchers recorded dose-dependent increases in action potential duration and early afterdepolarizations, mechanisms that precede torsades de pointes in humans. These effects occurred independently of nicotine, isolating the flavoring chemicals as the variable.

Observational data from the AHA 2023 scientific statement already linked e-cigarette use to endothelial dysfunction and oxidative stress, yet lacked arrhythmia endpoints. This new interventional evidence fills that gap while highlighting how high-nicotine pod devices deliver coolant doses orders of magnitude above older cig-a-like products. Regulatory filings show several major brands increased WS-23 content after 2022.

Absolute risk remains unquantified because no longitudinal human cohort has tracked incident atrial fibrillation or sudden cardiac arrest against coolant exposure biomarkers. Next steps require pharmacokinetic studies in habitual users plus Mendelian randomization analyses to separate coolant effects from nicotine and particulates.

FDA marketing denial decisions scheduled for late 2026 will test whether arrhythmia signals trigger flavor or coolant restrictions beyond current nicotine limits.