Case Presentation: 65-year-old female with past medical history of chronic myeloid leukemia (CML) and peripheral arterial disease (PAD) requiring drug eluting stent placement presented with symptoms of bradycardia and episodes of dizziness ongoing for 3 days. Of note, the patient was recently admitted in the hospital for pre-syncopal episode where cardiac workup was negative. Patient attributed symptom to Plavix and was switched to Brilinta. Patient was only on Brilinta for 3 days before onset of symptoms. The electrocardiogram revealed third-degree atrioventricular (AV) block. Both Dasatinib and Brilinta were held. During the hospitalization, the patient was started on dopamine drip and successfully underwent placement of permanent pacemaker. She was also transitioned back to Plavix for her PAD.
Discussion: Dasatinib is a second-generation tyrosine kinase inhibitor (TKI) with significant impact on BCR-ABL, making it an effective agent against Philadelphia chromosome positive CML. Cardiac arrhythmias, specifically third-degree AV block is one of the rare side effects noted with Dasatinib. We present a case of a Dasatinib induced third-degree AV block and emphasize the importance of recognizing associations as well as focus on prompt management for life-threatening cardiac arrhythmias.This case presentation brings an attention to a case where we have two offending drugs. Although there have been incidences of brady-arrhythmias with Brilinta, these events have been transient and have rarely led to high-degree of AV block. Dasatinib, however, is known to inhibit kinases even beyond the BCR/ABL, some involved in the cardiac function as well. Given that patient had been on Dasatinib for a longer duration than Brilinta and was known to have other toxicities from chemotherapy agents including pleural effusions and PAD, it was likely the offending agent. In our case, it may have been the onset of Brilinta which further put our patient at risk of developing AV block.
Conclusions: This case emphasizes rare side effects associated with Dasatinib as well as highlights possible exacerbating factor (Brilinta) leading to third-degree AV block. It is imperative to recognize the offending agents in a timely manner to adequately prevent life-threatening conditions.