Benefits of Chronic Atrial Pacing in Fontan Physiology with Sinus Node Dysfunction and Preserved Ejection Fraction: Novel Therapeutic Approach for Failing Fontan

Increased heart rate (HR) can reduce central venous pressure (CVP) in patients with preserved ventricular systolic function. We aimed to investigate whether this theory works in failing Fontan physiology. Pacemaker implantation (PMI) was performed in six Fontan patients (age: 6-40 years) with sinus node dysfunction (SND) without junctional rhythm (JR). Baseline median (interquartile [IQR]) values of CVP, ventricular end-diastolic pressure (EDP), and ejection fraction (EF) were 12 (11-15) mmHg, 13 (10-16) mmHg, and 57% (53%-64%), respectively. Before PMI, the relationships among HR, cardiac index (L/min/m²), CVP, and EDP were evaluated using atrial pacing. Additionally, we assessed chronic changes in hemodynamics and hepatorenal function after PMI. During baseline catheterization, HR was 51 (40-58) bpm. Atrial pacing was initiated at 60 (60-63) bpm and increased to 85 (80-93) bpm. Reductions were observed in CVP (from 12 [11-15] to 9 [8-11] mmHg, p < 0.05), EDP (from 13 [10-16] to 8 [6-8] mmHg), and an increase in cardiac index (from 2.7 [2.3-3.0] to 3.4 [3.2-4.1] L/min/m²). After 1 year of PMI with HR of 80 (70-83) bpm, sustained improvements were observed, including reductions in CVP (from 12 [11-15] to 10 [9-11] mmHg, p < 0.05), EDP (from 13 [10-16] to 9 [4-9] mmHg, p = 0.06), and ventricular end-diastolic volume index (from 85 [76-98] to 67 [53-76] ml/m², p < 0.05). Total bilirubin levels and renal resistive index also decreased (both p = 0.06). In conclusion, chronic atrial pacing therapy reduced CVP and ventricular volume in Fontan patients with preserved EF and SND, even in the absence of JR. Proactive PMI may prevent the progression of Fontan-associated end-organ dysfunction in these selected Fontan patients.