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Canadian Journal of Cardiology

EFFECT OF TAFAMIDIS ON GLOBAL LONGITUDINAL STRAIN USING A CORRECTION METHOD IN TRANSTHYRETIN CARDIAC AMYLOIDOSIS

      Background

      Various pharmacological options have been developed for TTR cardiac amyloidosis (TTR-CA), targeting different phases of the disease process. Tafamidis is a stabilizer of the TTR molecule that reduces CV mortality and CV-related hospitalization in patients with either wild-type or hereditary TTR CM. Echocardiography is an important tool in the diagnosis and follow-up of patients with TTR-CA, however, no echocardiographic markers of response to treatment with Tafamidis have been identified to date. Global Longitudinal Strain (GLS) is a measure that has clinical value in the diagnosis of TTR-CA. As atrial fibrillation is common in patients with TTR-CM, the GLS with the square root of the RR-interval (GLS/√(RR)) may offer an alternate method to assess GLS is this population. In this study, we aimed to evaluate the role of GLS/√(RR) to assess treatment response with Tafamidis.

      Methods and Results

      We conducted a single-center, retrospective case-control study of 48 patients with TTR-CM matched for age and sex. Twenty-four patients were treated with Tafamidis and 24 did not receive treatment. Patients underwent a baseline echocardiogram and at one-year post-initiation of Tafamidis. Clinical and laboratory characteristics are shown in Table 1. Two-dimensional speckle tracking echocardiography was analyzed offline using a vendor-neutral software (Epsilon Imaging). GLS was calculated as the average of strain from 3 long-axis views and then indexed to the square-root of the RR interval (GLS/√(RR)). 14 patients had atrial fibrillation. Over 12 months, GLS/√(RR) deteriorated less in the Tafamidis group by a median of 3.4% (IQR -3.8 – 10.4) compared with 13.3% (IQR 5.6 – 18.7) in the untreated group (p=0.002). Similarly, non-indexed GLS deteriorated less in the Tafamidis group by a median of 3.2% (IQR -3.5 – 8.4) compared with 11.6% (IQR 7.6 – 21.5) in the untreated group (P < 0.001). There was also a significant difference in the reduction in LVEF 3.2% (IQR -2 – 7) in the Tafamidis group versus 9.5% (IQR 6 – 20.3) in the untreated group (P < 0.001).