Heart Failure with Transient Left Bundle Branch Block in the Setting of Left Coronary Fistula

Coronary arterial fistulas are rare communications between vessels or chambers of the heart. Although cardiac symptoms associated with fistulas are well described, fistulas are seldom considered in the differential diagnosis of acute myocardial ischemia. We describe the case of a 64-year-old man who presented with left shoulder pain, signs of heart failure, and a new left bundle branch block (LBBB). Cardiac catheterization revealed a small left anterior descending (LAD)-to-pulmonary artery (PA) fistula. Diuresis led to subjective improvement of the patient's symptoms and within several days the LBBB resolved. We hypothesize that the coronary fistula in this patient contributed to transient ischemia of the LAD territory through a coronary steal mechanism. We elected to observe rather than repair the fistula, as his symptoms and ECG changes resolved with treatment of his heart failure. 1. Introduction Coronary arterial fistulas are rare cardiac anomalies that create new pathways of blood flow between coronary vessels and thoracic vasculature or chambers of the heart [1]. Although generally asymptomatic, patients can develop complications of thrombosis, congestive heart failure, rupture, endocarditis, and arrhythmias [2]. Here, we describe a patient with acute decompensated heart failure and transient left bundle branch block (LBBB), found to have an underlying left anterior descending (LAD-) to-pulmonary artery (PA) fistula. This case illustrates the potential of coronary fistulas to induce a clinical presentation of cardiac ischemia via a coronary steal mechanism. 2. Case Report A 64-year-old man with a history of congestive heart failure and stage IV chronic kidney disease secondary to uncontrolled hypertension and diabetes mellitus presented with three days of orthopnea and one night of intermittent left shoulder pain radiating to the back. Physical examination revealed a heart rate of 99 beats per minute and blood pressure of 149/71？mm？Hg with an oxygen saturation of 94% on 4 liters of oxygen. Bilateral rales were present in the lower and middle lung fields. Cardiac auscultation revealed distant heart sounds and a regular rate and rhythm without murmur. Jugular venous pressure was elevated to 10 cm H2O. Lower extremity pitting edema (2+) was present. Laboratory analyses were significant for a hematocrit of 24% and creatinine of 3.8？mg/dL. Cardiac enzymes were normal. Twelve-lead electrocardiography (ECG) revealed sinus rhythm at 94 beats per minute and a new LBBB. An acute myocardial infarction was suspected and the patient was taken for emergent