Unusual Cardiovascular Response to Sildenafil: Complete Heart Block in a Healthy Young Adult

Sildenafil, a phosphodiesterase-5 (PDE5) inhibitor, is widely used for erectile dysfunction and pulmonary hypertension, with its cardiovascular safety profile being well documented. However, its potential to induce conduction abnormalities remains largely unexplored, both due to a lack of clinical reports and limited mechanistic studies. While tachyarrhythmias have been frequently associated with sildenafil use, bradyarrhythmias, particularly complete heart block, are an unreported complication. We present the case of a young, healthy male who developed a transient complete heart block shortly after sildenafil ingestion. Despite no prior cardiac history and normal coronary angiography, he experienced severe bradycardia unresponsive to atropine but reverted to normal sinus rhythm with isoprenaline infusion. Mechanistically, sildenafil-induced hypotension, autonomic modulation, or transient myocardial ischemia may have contributed to atrioventricular (AV) nodal suppression. Previous reports have linked sildenafil to myocardial infarction and ventricular arrhythmias, but to our knowledge, no cases of transient complete heart block have been documented. This case expands the understanding of sildenafil's electrophysiological effects, emphasizing the need for awareness among clinicians prescribing PDE5 inhibitors. Further research is warranted to assess risk stratification for patients susceptible to sildenafil-induced conduction abnormalities.