C43-35 Unilateral Diaphragmatic Paralysis and Exertional Dyspnea Following Atrial Fibrillation Ablation

Abstract Introduction Phrenic nerve injury is a rare complication of atrial fibrillation (AF) ablation, often underrecognized as a cause of post-procedural dyspnea. This case highlights the importance of considering diaphragmatic paralysis in patients with new exertional shortness of breath after otherwise successful ablation. Case Report An 80-year-old woman with AF, chronic obstructive pulmonary disease (COPD), hypertension, and heart failure with preserved ejection fraction underwent pulmonary vein isolation and cavotricuspid isthmus ablation in October 2024. She presented two weeks later with acute dyspnea and orthopnea. Evaluation revealed a new left bundle branch block on electrocardiogram, and cardiac catheterization showed only minimal coronary artery disease and normal filling pressures. Diaphragm ultrasound and sniff testing both confirmed right hemidiaphragm paralysis, consistent with phrenic nerve injury secondary to ablation. The patient was managed conservatively with discontinuation of flecainide (started post-ablation), initiation of pulmonary rehabilitation, and continuation of triple-inhaler therapy (fluticasone-umeclidinium-vilanterol) for underlying COPD. Echocardiogram showed preserved left-ventricular systolic function and mild pulmonary hypertension. Right-heart catheterization confirmed normal cardiac output. Over the following months, she reported gradual improvement in dyspnea with pulmonary rehabilitation. Her rhythm remained in sinus on ambulatory monitoring, and she continued apixaban for stroke prevention per guideline recommendations. Discussion Phrenic nerve injury is a rare complication of AF ablation, reported in fewer than 1% of procedures. It typically results from thermal damage along the right superior pulmonary vein or superior vena cava, where the phrenic nerve runs close to ablation sites. Diagnosis can be confirmed with fluoroscopy, sniff testing, or diaphragm ultrasound, the latter offering a noninvasive and reliable bedside tool. Management is supportive, focusing on pulmonary rehabilitation and close follow-up, as many patients experience gradual recovery of diaphragmatic function. Multidisciplinary follow-up between electrophysiology and pulmonary specialists is important to differentiate phrenic nerve injury from heart-failure-related dyspnea and to guide recovery. Conclusion Phrenic nerve injury should be considered in any patient who develops new dyspnea following AF ablation. Early recognition and supportive care can promote recovery and prevent unnecessary interventions for presumed heart failure. This abstract is funded by: None