Right atrial reservoir strain strongly predicts improvement in right ventricular to pulmonary artery coupling in patients with Transthyretin Amyloid Cardiomyopathy treated with Tafamidis

Background: Right ventricular to pulmonary artery (RV-PA) uncoupling in patients with transthyretin amyloid cardiomyopathy (ATTR-CM) is associated with unfavorable clinical events and a poor prognosis. However, the effect of tafamidis on RV-PA coupling and the predictive value of right atrial (RA) reservoir strain on RV-PA coupling has been poorly investigated.

The purpose of this study was to evaluate the effect of tafamidis on RV-PA coupling and the prognostic role of RA reservoir strain on RV-PA coupling over 12 months of treatment.

Methods: 101 patients with ATTR-CM treated with 61 mg tafamidis daily who underwent multimodality imaging evaluation at baseline by cardiovascular magnetic resonance (CMR) feature tracking and echocardiography were retrospectively studied. The 12 months follow-up included echocardiographic assessment of RV-PA coupling. A significant improvement RV-PA coupling was defined as a >10 % improvement in the tricuspid annular plane systolic excursion/ pulmonary artery systolic pressure (TAPSE/PASP) ratio from baseline.

Results: Over 12 months of tafamidis treatment, 21.8% of patients experienced significant improvement in RV-PA coupling. Patients with improved RV-PA coupling were at an earlier stage of disease prior to tafamidis treatment with less dilated RV, less severe RV-PA uncoupling and higher RA reservoir strain (12.9 ±1.9 % vs 9.6 ±2.6 %, P< 0.001) compared to patients without improvement in RV-PA coupling. CMR-derived baseline RA reservoir strain was the strongest predictor of improvement in RV-PA coupling (HR 0.43, 95% CI 0.23-0.82, P =0.011) followed by baseline NT-proBNP (HR 0.998, 95% CI 0.996-0.999, P=0.049).

Conclusion: RA reservoir strain has a significant prognostic value on RV-PA coupling in patients with ATTR-CM treated with tafamidis. CMR-based evaluation of RA reservoir strain before tafamidis initiation may use as predictor of therapeutic response and improvement of RV function in patients with ATTR-CM.