Positive Tc-99m Pyrophosphate Scintigraphy Predicts Thromboembolic Risk in Patients with Congestive Heart Failure and Atrial Fibrillation

Abstract

Background Tc-99m pyrophosphate scintigraphy (PYP) has unmasked a high community prevalence of wild-type transthyretin cardiac amyloidosis (ATTRwt-CA), which is an increasingly recognized etiology of congestive heart failure (CHF) in the elderly. CHF is a known component of the CHA2DS2-VASc score that predicts thromboembolic risk in atrial fibrillation (AF). However, the impact of ATTRwt-CA on thromboembolic risk in AF is unknown. Hypothesis We hypothesized that ATTRwt-CA independently predicts thromboembolism in CHF patients with atrial fibrillation. Methods We studied patients with underlying CHF who underwent PYP between 6/2015 and 6/2019. Positive PYP was defined as Perugini grade ≥2 along with heart-to-contralateral lung ratio of ≥ 1.5 on planar image, and diffuse myocardial tracer uptake on the SPECT. Those with positive PYP, negative serum studies for AL amyloidosis and no transthyretin gene mutation were diagnosed with ATTRwt-CA. We compared the prevalence of AF in patients with and without ATTRwt-CA and the incidence of thromboembolism (stroke, transient ischemic attack or systemic embolism) in AF patients with ATTRwt-CA (AF-ATTR) and without (AF-controls). Results Of 277 patients referred for PYP, 77 (28%) had ATTRwt-CA. The prevalence of AF was markedly higher in patients with ATTRwt-CA (n=68, 88%) compared to patients with negative PYP (n=77, 39%, p Conclusion ATTRwt-CA is a strong predictor of thromboembolism in patients with AF, independent of CHA2DS2-VASc score, septal thickness or left atrial size.