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Large Coronary Artery Fistula in an Adult: Rarity, Complexity, and Uncertainty

Updated: May 7

Rose Tompkins, MD, FACC and Evan M. Zahn, MD, FACC, FSCAI

Introduction

Coronary Artery Fistula (CAF) is a rare connection between a coronary artery and a chamber of the heart or major thoracic blood vessel without an intervening capillary bed. Most CAFs are congenital, can involve one or more coronary arteries, and have a similar prevalence in males and females.[1] The true incidence of CAFs is difficult to determine as many are small and likely never diagnosed or only discovered incidentally on imaging studies obtained for other reasons. CAFs have been seen in 0.3% of patients with Congenital Heart Disease,[2] 0.06% of children undergoing echocardiography,[3] 0.09-0.22% of adults undergoing coronary angiography,[1,4-6] and 0.09-0.90% of adults undergoing Coronary Computed Tomography Angiography.[7-10] There is considerable anatomic and hemodynamic variability observed among CAFs. A majority of CAFs seen in adults are smaller and clinically silent. However, a smaller subset will present with larger, symptomatic fistulas attributed to a significant arteriovenous shunt or myocardial ischemia from a coronary steal phenomenon.[11] We present the case of a large CAF as an unexpected etiology of heart failure in an older adult and review the unique management challenges encountered in these rare cases.



FIGURE 1 Transthoracic Echocardiography A) Parasternal long-axis view demonstrating a dilated LCx and CS. B, C) Short-axis view at the level of the aortic root showing a dilated LM with laminar flow by color Doppler. D, E) Right-ventricular inflow view showing a dilated CS with high velocity turbulent flow from the CS into the RA per color Doppler. F) Continuous wave spectral Doppler showing that the high velocity flow from the CS into the RA is continuous throughout the cardiac cycle. LV, left ventricle; LA, left atrium; Ao, aorta; CS, coronary sinus; LCx, left circumflex coronary artery; RVOT, right ventricular outflow tract; LM, left main coronary artery; RV, right ventricle; RA, right atrium.



Case Presentation

A 58-year-old woman presented with symptoms of palpitations and shortness of breath. Her history was remarkable for a life-long cardiac murmur that was never fully investigated. She developed Paroxysmal Atrial Fibrillation (pAF) in her mid-40s that was managed with beta-blocker therapy. Systemic anticoagulation was attempted but not tolerated due to conjunctival bleeding and epistaxis, with further diagnostic evaluation revealing Von Willebrand Disease (VWd). In the two years preceding her presentation, she developed an increasing frequency of pAF episodes, as well as, worsening dyspnea on exertion, reduced exercise tolerance, substernal chest pressure, and new onset lower extremity edema. Her exam was notable for a widened pulse pressure, continuous murmur along the left sternal border and trace bilateral pitting edema.


Her resting electrocardiogram was normal. Transthoracic echocardiography showed normal biventricular systolic function with four-chamber dilation, no significant valvular disease, and a massively dilated left main coronary artery and coronary sinus. Color and spectral Doppler showed continuous flow from the coronary sinus into the right atrium which was suspicious for a CAF from the left coronary system to the coronary sinus given the significant dilation of the left main coronary artery (Figure 1). Coronary Computed Tomography Angiogram (CCTA) confirmed a large CAF originating from the distal left circumflex coronary artery and draining into the coronary sinus with a remarkably tortuous course (Figure 2). A pharmacologic nuclear stress test was negative for myocardial ischemia. Cardiac catheterization demonstrated a large left-to-right intracardiac shunt (Qp:Qs 2.5:1.0), elevated pulmonary artery pressure (50/21 mmHg, mean 32 mmHg), capillary wedge pressure of 16 mmHg, and a calculated pulmonary vascular resistance of 1.6 WU or 2.5 WU/m2. The left anterior descending and proximal obtuse marginal branches appeared more normal in caliber.



To read the full article, please go to the April 2020 Issue of CCT.

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