Incidence and risk factors for pacemaker implantation in light chain and transthyretin cardiac amyloidosis

Abstract

Abstract Background The incidence and risk factors of pacemaker (PM) implantation in patients with cardiac amyloidosis (CA) are largely unexplored. Purpose We sought to characterise the trends in the incidence of permanent PM and to identify baseline predictors of future PM implantation in light chain (AL) and transthyretin (ATTR) CA. Methods Multicentre, retrospective, observational study. Consecutive patients with AL and ATTR-CA diagnosed or referred at participating Centres between 2017 and 2020 were included. Clinical data recorded within ± 1 month from baseline evaluation were collected from electronic medical records. The primary outcome of the study was the need for clinically-indicated PM implantation. Reversible causes of conduction system disease were systematically ruled out before PM implantation. Patients with PM (n=41) and/or permanent defibrillator in situ (n=13) at the time of CA diagnosis were excluded. Results The study population consisted of 405 patients: 29.4% AL, 14.6% variant ATTR and 56% wild-type ATTR; 82.5% were males, with median age 76 years. During a median follow-up of 33 months (interquartile range 21–46), 36 (8.9%) patients experienced the primary outcome: 10 patients with AL-CA, 2 with variant ATTR-CA and 24 with wild-type ATTR-CA (p=0.08). At multivariable analysis, history of atrial fibrillation (hazard ratio [HR] 3.80, p=0.002), PR interval (HR 1.013, p=0.002) and QRS >120 ms (HR 4.7, p=0.001) on baseline ECG were independently associated with PM implantation (Figure 1). In the individual patient, the contemporary presence of these 3 factors yielded the highest risk of PM implantation (HR 6.26, p=0.003). Conclusion In a large cohort of AL and ATTR-CA, the incidence of PM implantation was high accounting for ≈9% of patients in the 3 years following the diagnosis. History of atrial fibrillation, longer PR interval and QRS >120 ms identified CA patients at high-risk of future PM implantation (Figure 2). CA patients with these features might need close monitoring during follow-up for the development of conduction system disease requiring PM implantation. Funding Acknowledgement Type of funding sources: None.