Incidence and Predictors of Ventricular Arrhythmias in Transthyretin Amyloid Cardiomyopathy

Background: Wild-type transthyretin amyloid cardiomyopathy (wtATTR-CM) is characterized by heart failure, conduction abnormalities and arrhythmias. The incidence of ventricular arrhythmias, particularly ventricular tachycardias (VTs), in wtATTR-CM is unclear. With the development of targeted therapies and improved overall prognosis, there is an unmet need to identify patients at high risk for VTs who might benefit from ICD therapy. Methods: Between 2017 and 2022, 72 patients diagnosed with wtATTR-CM were prospectively evaluated for the presence of ventricular arrhythmias using a Holter ECG. VTs were defined as >3 consecutive beats with a heart rate > 100 beats per minute originating from a ventricle. Results: The incidence of VTs was 44% (n = 32/72) in unselected wtATTR-CM patients. Patients with VT showed significantly more severe left ventricular (LV) hypertrophy (septum diameter 21 & PLUSMN; 2.6 vs. 19 & PLUSMN; 3.0 mm, p = 0.006), reduced LV ejection fraction (47 & PLUSMN; 8 vs. 52 & PLUSMN; 8%, p = 0.014) and larger left atria (32 & PLUSMN; 7 vs. 28 & PLUSMN; 6 mm(2), p = 0.020), but no differences in cardiac markers such as NTproBNP and troponin. In a multivariable model, LV hypertrophy (LV mass indexed, OR = 1.02 [1.00-1.03], p = 0.031), LV end-diastolic diameter (OR = 0.85 [0.74-0.98], p = 0.021) and LV end-systolic diameter (OR = 1.19 [1.03-1.349], p = 0.092) were predictive for VT occurrence with an area under the receiver operating characteristic of 0.76 [0.65-0.87]. Conclusions: The incidence of ventricular arrhythmia in wtATTR-CM is high and is associated with an advanced stage of left ventricular disease. Further studies are needed evaluating the role of VTs in predicting sudden cardiac death and the benefit of ICD therapy in wtATTR-CM.