Resolution of Symptomatic Intermittent Sinoatrial Exit Block Associated With Unstable Angina Following Percutaneous Coronary Intervention

Bradyarrhythmia commonly occurs because of degenerative fibrosis in the conductive system. Ischemic disease is a rare etiology and limited cases have demonstrated direct evidence of ischemia to the sinus node vessels. We report a 62-year-old Hispanic male with a significant medical history of diabetes mellitus type II (DM II), hypertension, and dyslipidemia who was admitted to our hospital for symptomatic sinoatrial (SA) exit block. Patient had no electrolyte abnormalities and our differential included ischemic vs. fibrotic or infiltrative pathologies, giving symptomatic bradycardia, cardiac chest pain, and high-risk factors for coronary artery disease. We decided to take him for cardiac catheterization which revealed sluggish, pulsatile flow into the SA nodal artery due to severe stenosis of the ostial right coronary along with sever distal left circumflex (LCX) lesion. The flow into the sinus nodal artery (SNA) markedly improved post percutaneous coronary intervention (PCI) of the right coronary artery (RCA) and distal LCX and restoration of flow into SNA. Resolution of his bradyarrhythmia and symptoms post intervention confirmed our suspicious for reversible ischemic sinus node dysfunctions. Therefore, ischemic pathologies should be thought of when other common etiologies are less likely. Coronary angiogram should be considered prior to pacemaker evaluation in these setting to avoid missing reversible causes of bradyarrhythmia.