Correlation of Quantitative Tc DPD Scintigraphy With Echocardiographic Alterations in Left Atrial Parameters in Transthyretin Amyloidosis.

Aim: Cardiac transthyretin amyloidosis (ATTR) patients have high rates of atrial arrhythmias. We evaluated echocardiographic structural and functional left atrial (LA) parameters and correlated these with technetium-99m 3,3-diphosphono-1,2-propanodicarboxylic acid (Tc-DPD) bone scintigraphy tracer uptake within the LA in ATTR patients.

Methods: ATTR patients (wild-type, hereditary and asymptomatic transthyretin [TTR] variant carriers) who had undergone Tc-DPD and transthoracic echocardiogram (TTE) were selected. Quantitative Tc-DPD uptake analysis and echocardiographic evaluation of LA structural and functional parameters was performed.

Results: Forty (40) ATTR patients (wild-type n=17; hereditary ATTR and TTR variant carriers n=23; median age 68.8±22 years) were included. TTE parameters including indexed LA minimum (LAV) (r=0.66), and LA maximum volumes (LAV) (r=0.64), LA emptying fraction (LAEF) (r=-0.68), LA function index (LAFI) (r=-0.70) and reservoir strain (ƐR) (r=-0.70) (p<0.001 for all) demonstrated good correlation to LA tracer uptake. Normal LA volume (LAV and LAV) and function (LAEF, LAFI and ƐR) was observed in hereditary ATTR and TTR variant carriers without cardiac tracer uptake. The subgroup of ATTR patients with atrial fibrillation/flutter demonstrated increased LAV and LAV with further reduction in LA function (LAEF, LAFI and ƐR). Receiver operating characteristic curves demonstrated strong diagnostic accuracies for LA structural (LAV and LAV; area under the curve [AUC] of 0.83 and 0.84 respectively) and functional (LAEF, LAFI and ƐR; AUC 0.81, 0.88 and 0.85, respectively) parameters.

Conclusion: Left atrial structural and functional parameters demonstrated good correlations with quantitative Tc-DPD tracer LA uptake. Echocardiography and Tc-DPD scintigraphy may have significant roles in identification and surveillance of ATTR patients likely to develop atrial arrhythmias.