Indication and electrical performance of conventional, resynchronisation and conduction system pacing in Transthyretin amyloid cardiomyopathy

Background:Conduction system disorders and arrhythmias may require pacemaker or ICD implantation in transthyretin amyloid cardiomyopathy (ATTR-CM).The optimal mode of pacing in ATTR-CM remains unknown.Objective: To compare electrical performance and clinical outcomes of conventional, resynchronisation and conduction system pacing in ATTR-CM. Methods:In this observational study, the effects of cardiac pacing were investigated in 250 consecutive ATTR-CM patients presenting at Inselspital Bern between June 2019 and February 2023.Results: During follow-up, 67 of 250 patients (26.8%) received a pacemaker.Implantation of conventional single-or dual-chamber (VVI/DDD) pacemakers was more common before ATTR-CM diagnosis (n=17/25; 68%), physiological pacing (CRT/CSP) was increasingly utilized thereafter [n=24/42 (57.1%)].Sick sinus syndrome [n=11/35 (31.4%) vs. 6/32 (18.8%] and higherdegree AV-block [n=20/35 (57.1%) vs. 9/32 (28.1%)] were more common indications for VVI/DDD, with pursuit of a pace/ablate strategy [n=12/32 (37.5%)] and heart failure [n=5/32 (15.6%)] contributing significantly to implantation of CRT/CSP.QRS duration width was significantly lower with CSP [122ms (IQR:120-139)], compared to CRT [155ms (IQR:141-160)] or VVI/DDD [160ms (IQR:144-180), p<0.001].While LV/LBBAP pacing capture thresholds were significantly lower after CSP [0.75V (IQR: 0.5-1.2)]compared to CRT [1.3V (IQR:1.0-1.6)p=0.049] at implantation, no significant differences for atrial or ventricular lead performance were observed during follow-up (p>0.05).Patients referred for CRT/CSP had a higher incidence of heart failure (p=0.014) and more common heart failure hospitalizations (p=0.03),however, mortality was not significantly different (p=0.28). Conclusions:Offering stable electrical performance and improved resynchronization, the effect of conduction system pacing on clinical outcomes warrants further exploration in ATTR-CM.