Abstract Body (Do not enter title and authors here): Discussion of Case: A 69-year-old male with HF-rEF secondary to nonischemic cardiomyopathy presented with persistent NYHA class III symptoms despite optimized medical therapy, CRT-D implantation, and prior interventions for atrial fibrillation. Echocardiography revealed severe left ventricular (LV) dilation (LVIDd 7.4 cm, EF 25-29%) and mildly depressed right ventricular function with elevated pulmonary artery systolic pressures (49-54 mmHg). After declining LVAD therapy, the patient was scheduled for baroreceptor activation therapy (BAT) implantation as an alternative treatment. In February 2024, the Barostim Neo system was implanted without complications, but a significant increase in premature ventricular contraction (PVC) burden was noted, rising from 2.6% pre-procedure to 33% within two months and reduced biventricular pacing percentage. In May 2024, PVC ablation was performed, targeting the RVOT/LVOT, reducing the PVC burden to 8%. Both CRT-D and BAT devices were reactivated post-ablation. However, subsequent echocardiography revealed a further decline in LV function, with EF dropping to 20-24%. RV function also deteriorated. Given the persistent decline in cardiac function and potential PVC recurrence due to BAT activation, the device was deactivated in July 2024. Following deactivation, the PVC burden decreased significantly to 1.5%, similar to pre-implantation levels. There was no improvement in the cardiac function with EF still at 24%.

Discussion: Baroreceptor activation therapy (BAT) can reduce adrenergic overdrive by stimulating carotid baroreceptors, potentially improving heart failure with reduced ejection fraction. The following clinical case shows a peculiar side effect potentially attributable to the use of BAT. The development of arrhythmias in this case may indicate an adverse effect contrasting with the antiarrhythmic potential of BAT, possibly due to parasympathetic overactivity or autonomic instability. While the patient may appear to be an ideal candidate for the device, an individualized approach may offer more benefits.