Predictors of left atrial appendage thrombus despite NOAC use in nonvalvular atrial fibrillation and flutter

Abstract

ObjectiveA small but significant proportion of patients with atrial fibrillation or atrial flutter (AF) develop left atrial appendage thrombus (LAAT) despite non-vitamin K antagonist oral anticoagulant (NOAC) prescription. This study examines clinical and echocardiographic risk factors associated with LAAT by transesophageal echocardiogram (TEE) despite NOAC use in patients with non-valvular AF, to inform the decision whether a TEE should be performed prior to cardioversion. MethodsWe compared clinical and echocardiographic characteristics of patients with LAAT despite NOAC prescription for >3 weeks (n = 38) with a consecutive sample of patients on NOAC without LAAT (n = 101). ResultsThe prevalence of LAAT despite NOAC prescription was 2.6%. Left atrial dilation (adjusted odds ratio [aOR] 3.310, 95% CI 1.144–9.580, p = 0.02) and greater CHA2DS2-VASC score (per-point increase, aOR 1.293, 1.027–1.628, p = 0.03) increased the odds for LAAT. Higher LVEF (per 5%, aOR 0.834, 0.704–0.987, p = 0.03) and presence of severe mitral regurgitation (aOR 0.147, 0.048–0.446, p = 0.002) were protective against LAAT. LAA emptying velocities were also independently associated with presence of LAAT (aOR per 10 cm/s, 0.46, 0.27–0.77). ConclusionLeft atrial dilation, greater CHA2DS2-VASC score, absence of severe mitral regurgitation and lower left ventricular ejection fraction are associated with LAAT despite NOAC therapy. In addition to suspected NOAC noncompliance, presence of such high-risk features may warrant pre-cardioversion TEE. Similarly, in patients with LVEF > 50% and CHA2DS2-VASC < 2, risk of LAAT was exceedingly low and thus TEE before cardioversion is low-yield.