Indication and electrical performance of conventional, resynchronization, and conduction system pacing in transthyretin amyloid cardiomyopathy.

BACKGROUND

Conduction system disorders and arrhythmias may require pacemaker (PM) or implantable cardioverter-defibrillator implantation in transthyretin amyloid cardiomyopathy (ATTR-CM). The optimal mode of pacing in ATTR-CM remains unknown.

OBJECTIVE

This study aimed to compare the electrical performance and clinical outcomes of conventional, resynchronization, and conduction system pacing (CSP) in ATTR-CM.

METHODS

In this observational study, the effects of cardiac pacing were investigated in 250 consecutive patients with ATTR-CM presenting at Inselspital Bern between June 2019 and February 2023.

RESULTS

During follow-up, 67 of 250 patients (26.8%) received a PM. Implantation of conventional single- (VVI) or dual-chamber (DDD) PMs was more common before ATTR-CM diagnosis (n = 17 of 25; 68%), and physiological pacing (cardiac resynchronization therapy [CRT]/CSP) was increasingly used thereafter (n = 24 of 42 [57.1%]). Sick sinus syndrome (n = 11 of 35 [31.4%] vs 6 of 32 [18.8%]) and higher-degree atrioventricular block (n = 20 of 35 [57.1%] vs 9 of 32 [28.1%]) were more common indications for VVI/DDD, with pursuit of a pace/ablate strategy (n = 12 of 32 [37.5%]) and heart failure (HF) (n = 5 of 32 [15.6%]) contributing significantly to implantation of CRT/CSP. QRS duration width was significantly lower with CSP (122 ms [interquartile range {IQR} 120-139]) than CRT (155 ms [IQR 141-160]) or VVI/DDD (160 ms [IQR 144-180]; P < .001). Although left ventricular/left bundle branch area pacing capture thresholds were significantly lower after CSP (0.75 V [IQR 0.5-1.2]) than CRT (1.3 V [IQR 1.0-1.6]; P = .049) at implantation, no significant differences for atrial or ventricular lead performance were observed during follow-up (P > .05). Patients referred for CRT/CSP had a higher incidence of HF (P = .014) and more common HF hospitalizations (P = .03); however, mortality was not significantly different (P = .28).

CONCLUSION

Offering stable electrical performance and improved resynchronization, the effect of CSP on clinical outcomes warrants further exploration in ATTR-CM.ClinicalTrials.gov identifier: NCT04776824.