Background

Transthyretin amyloid cardiomyopathy (ATTR-CM) is a rare cause of myocardial thickening caused by amyloid deposit and consecutive deterioration of heart function. Left atrial (LA) strain was shown to be one of the early affected and rapid deteriorating parameters in ATTR-CM. Tafamidis is a novel transthyretin-binding drug showing reduction of all-cause mortality and improvement of left ventricular function in ATTR-CM. The impact of tafamidis on left atrial strain in patients with ATTR-CM has been barely investigated.

Purpose

In an ongoing, prospective, multicentric trial, we seek to evaluate the effect of tafamidis (61mg) on left atrial function, especially on left atrial strain. In this abstract we present preliminary results.

Methods

In this ongoing trial we seek to enroll 250 patients with either wildtype or hereditary ATTR-CM under therapy with tafamidis. Serial echocardiographic examinations (TTE) are planned every 12 months up to three years of therapy. A group of 50 patients not suitable for tafamidis therapy or discontinuation of therapy due to side effects will be analysed for comparison. Standard echocardiographic examination, including parameters of systolic and diastolic function, analysis of left ventricular global longitudinal strain (LVGLS) and left atrial reservoir-, conduit- and contraction strain, will be performed. Quality of life will be monitored by the Kansas City Cardiomyopathy Questionnaire-Overall Summary (KCCQ-OS).

Results 

In this preliminary analysis, we assessed 20 patients with proven ATTR-CM. All patients were in sinus rhythm during TTE. Mean septal thickness (IVSd) was 20.1cm (±3.6), mean LVEF 52.9% (±6.9), mean LVGLS 10.5 (±2.0), mean LAVI 59.9cm²/m²BSA (±17.9), mean E/E’ 15.7 (±3.7), mean framerate for left atrial strain measurements 42fps, mean left atrial reservoir strain (LASr) 12.7% (±9.3), mean left atrial conduit strain (LAScd) 7.7% (±5.1), mean left atrial contraction strain (LASct) 5.1% (±4.5). Mean duration of treatment with tafamidis at the date of follow up examination was 16 months. IVSd (p=0,33), LVEF (p=0.49), GLS (p=0.96); LAVI (p=0.12) and E/E´ (p=0.17) showed no significant difference between baseline and follow-up. Mean deterioration of LASr was -2.5%(p=0.27), of LAScd was -1.3% (p=0.19), of LASct was -1% (p=0.03), of which only LASct was significantly lower compared to baseline measurements.

Conclusion

In this preliminary analysis, LA longitudinal function in ATTR-CM patients showed slower deterioration under treatment with tafamidis than expected in untreated natural course. Final results will be awaited in 2023. We expect that LA strain analysis will be an appropriate marker for disease specific therapy monitoring.