FORCE Registry Study Finds Clinically Significant Difference in Arrhythmia Rates Between Extracardiac Conduit and Lateral Tunnel Approaches in Fontan Surgery

A multicenter study¹ led by faculty from the Heart Institute at UPMC Children’s Hospital of Pittsburgh evaluated long-term outcomes in Fontan surgery patients who had either an extracardiac conduit (ECC) or lateral tunnel (LT) approach, the two most common ways to achieve palliation for single ventricle circulation.

The study’s findings are based on data from the Fontan Outcome Registry Using Cardiac Magnetic Resonance Examinations (FORCE) and were published in The Annals of Thoracic Surgery in December 2025.

For this long-term outcome analysis, the study team evaluated and compared data on 1,290 patients who had either the ECC or LT. The follow-up period was 15 years postsurgery. The analysis focused on the outcomes and potential complications associated with the Fontan procedure, including atrial arrhythmias, transplant listing, end-organ dysfunction, protein-losing enteropathy, plastic bronchitis, and the need for catheter-based interventions.

Laura Seese, MD, MS, clinical instructor of pediatric cardiothoracic surgery at the Heart Institute was the first author of the study.

Clinical Findings of Significance

The most important finding from the study with respect to long-term outcomes between the ECC and LT approaches was the difference in atrial arrhythmia burden. Sustained atrial arrhythmias occurred three times more often in patients who had a LT Fontan (15%) compared with those who had the ECC (5%). Over the full follow-up period, the extracardiac conduit was associated with a 67% lower hazard of developing sustained atrial arrhythmias.

This difference became more pronounced over time. At 5, 10, and 15 years, patients with the ECC consistently showed greater freedom from atrial arrhythmias.

This finding related to atrial arrhythmia is clinically important because it is one of the most frequent and difficult complications seen in Fontan patients that routinely lead to hospital admissions and worse symptoms over time, including serious cardiac rhythm instability

“These findings reinforce the long-recognized relationship between atrial surgical suture lines and arrhythmia risk,” Dr. Seese says. “Because the extracardiac conduit avoids sutures inside the atrium, it likely reduces the substrate for future tachyarrhythmias.”

Dr. Seese and colleagues also examined a combined set of negative outcomes, including arrhythmias, death, transplant listing, protein-losing enteropathy, plastic bronchitis, and the need for catheter procedures. This combined outcome was more common in the LT versus the ECC group – 32% of patients versus 20%, respectively. However, when the team removed the presence of atrial arrhythmias from the combined measure outcome analysis, the difference between groups was not statistically significant.

“This analysis shows that the advantage of the ECC is almost entirely due to its lower rate of atrial arrhythmias, not other complications,” Dr. Seese says.

One additional difference seen between the ECC and LT groups was the rate of subsequent catheter-based interventions. These procedures were needed more often in patients with the LT approach, but the absolute difference in the outcome was relatively small

“From a clinical perspective, ECC appears to offer a long-term advantage in reducing atrial arrhythmias, which are among the most consequential complication in this population,” Dr. Seese says. “For clinicians caring for patients who have had the LT approach, the findings from our study highlight the importance of proactive rhythm surveillance and early electrophysiology engagement. The findings also support the continued widespread use of the extracardiac conduit approach when anatomy and patient characteristics are favorable.”

Reference

1. Seese L, Schiff M, Morell VO, Tran M, Arora G, Olivieri LJ, Follansbee C, Christopher AB, Kreutzer J, Fogel M, Medina MC, Diaz-Castrillon CE, Da Fonseca Da Silva L, Da Silva JP, Rathod RH, Alsaied T; FORCE Investigators. Multicenter Comparison of Long-Term Outcomes: Extracardiac Conduit Fontan vs Lateral Tunnel Fontan at 15-Year Follow-Up. Ann Thorac Surg. 2025 Dec; 120(6): 1115-1123.

Further Reading

Read another recent article on UPMCPhysicianResources.com about FORCE Registry research related to extracardiac conduit and lateral tunnel approaches.