Additional factors underlying pacing induced cardiomyopathy in patients underwent right ventricular pacing and his bundle pacing. Author's reply
Abstrakt
We agree that concomitant diseases such as cardiac sarcoidosis (CS) and amyloidosis (CA) might influence the clinical course of patients with bradycardia. The clinical spectrum of transthyretin cardiac amyloidosis (ATTR-CA) symptoms includes advanced conduction disorders requiring pacemaker implantation.
It had been documented that 3%-13% of patients with ATTR-CA had pacemakers implanted before they were diagnosed with CA.[1] However, in the European population, the prevalence of ATTR-CA in pacemaker patients was very low (only 2%) [2]. Cardiac sarcoidosis (CS) also leads to advanced symptomatic atrioventricular blocks, and according to Kandolin et al. [3], it was the first symptom in up to 44% of patients with diagnosed CS.
However, the prevalence of CS remains very low in the European population, where it is a rare condition. We initiate further diagnostic steps only if other risk factors are present.[3] Therefore, we believe that the low prevalence of these diseases and the randomized study design should not affect the differences in the left ventricular ejection fraction between studied groups.
On the other hand, we agree that due to the pathophysiology of the diseases, scanning for CS and CA could be helpful while measuring the markers of collagen metabolism.