Kato A, Sato J, Yoshii K, Yoshida S, Nishikawa H, Ohashi N, Sakurai T, Sakurai H, Hata T, Yoshikawa T. J Cardiol. 2021 Feb 26:S0914-5087(21)00042-3. doi: 10.1016/j.jjcc.2021.02.005.
Take Home Points:
- The indication of Fontan conversion (FC) from atriopulmonary connection (APC) to total cavopulmonary connection (TCPC) is unclear.
- Fontan conversion is a safe and feasible procedure to bring APC patients back onto the same track of primary TCPC patients in terms of hemodynamics as well as arrhythmia.
- The antiarrhythmic procedure should be carefully chosen because sinus node dysfunction can frequently occur and FC itself would reduce the risk of arrhythmia.
Commentary from Dr. Manoj Gupta (New York, USA), section editor of Pediatric & Fetal Cardiology Journal Watch:
The Fontan procedure, which is the treatment of choice for patients with functionally univentricular hearts, has been modified by the Bjork, lateral tunnel, and extracardiac total cavopulmonary connection (TCPC) procedures since the introduction of its initial version—the atriopulmonary connection (APC)—by Fontan et al. in the 1970s.
Fontan conversion, which entails connecting the inferior vena cava to the pulmonary artery using an artificial conduit, combined with arrhythmia surgery has been introduced. Possible benefits of prophylactic Fontan conversion in asymptomatic APC patients are improving cardiac output as well as preventing new onset of atrial tachyarrhythmia. On the other hand, the long-term hemodynamic outcome of patients after Fontan conversion compared with that of patients after primary TCPC is unknown. In this study, the sought to compare the midterm outcomes after prophylactic and therapeutic Fontan conversion with those after primary TCPC.
A total of 54 consecutive patients undergoing either Fontan conversion (n = 30) or primary TCPC (n = 24), followed by cardiac catheterization for postoperative hemodynamic evaluation at over 18 years of age between July 2005 and April 2019, were included in the study
The included 52 patients were divided into three groups: p-FC, consisting of 15 asymptomatic APC patients who underwent prophylactic Fontan conversion; t-FC, consisting of 13 symptomatic APC patients who received therapeutic Fontan conversion [including arrhythmia (n = 11), heart failure (n = 1), and protein-losing enteropathy (n = 1)]; and p-TCPC, consisting of 24 patients who underwent primary TCPC.
Tricuspid atresia turned out to be the most frequent diagnosis in patients receiving Fontan conversion procedure and the majority of patients in the t-FC (69%) and p-FC (93%) groups were found to have a dominant left ventricle (p = 0.71).
The initial Fontan procedure was performed at the ages of 7.5 (2.3–18.7), 4.7 (1.4– 10.1), and 6.7 (2.9–26.3) years in the t-FC, p-FC, and p-TCPC groups, respectively. The patients in the t-FC and p-FC groups underwent Fontan conversion at 24.4 (14.1–37.7) and 20.3 (8.0–25.6) years of age, respectively.
Before Fontan conversion, nine cases of atrial tachycardia (69%), one case of ventricular tachycardia (8%), and one case of sick sinus syndrome (SSS; 8%) were found in the t-FC group, all of which were managed with concomitant antiarrhythmic surgery.
Overview of the patients who underwent therapeutic Fontan conversion (t-FC). The second row indicates pre-operative rhythm (the dotted boxes); the third row indicates anti-arrhythmic surgeries performed at the time of the Fontan conversion (the bold boxes); the fourth and fifth rows indicate cardiac rhythm and devices required post-operatively, respectively. APC, aortopulmonary connection; AT, atrial tachycardia; AVB, atrioventricular block; CRT-P, cardiac resynchronization therapy pacing; JR, junctional rhythm; RA, right atrium; SSS, sick sinus syndrome; VT, ventricular tachycardia.
No difference in central venous pressure, aortic pressure, and cardiac index was observed across the three groups. Similarly, the levels of brain natriuretic protein (BNP)—which were found to be 34.3 (9.7–93.5), 10.4 (4.9–59.2), and 21.7 (4.9–365.5) in the t-FC, p-FC, and p-TCPC groups, respectively—exhibited no significant difference (p = 0.22).
Fontan conversion with the Maze procedure has emerged as a tertiary prevention strategy for those with previous APCs and tachyarrhythmia. The present study revealed that this procedure is both prophylactically and therapeutically feasible and effective and that it can yield the same outcomes in conventional APC patients as those observed with the contemporary primary extracardiac TCPC patients.
Tachyarrhythmia in patients with univentricular hearts is known to be a predictor of worse outcomes, especially in APC patients. Thus, antiarrhythmic interventions, such as the Maze procedure, combined with Fontan conversion, are likely to change the deleterious clinical course in these patients. In this cohort, arrhythmia was very well controlled following Fontan conversion that nearly half of the patients in the t-FC group experienced no recurrence without antiarrhythmic medications. Moreover, no newly developed case of tachyarrhythmia was observed in the p-FC group, suggesting the strategy, Fontan conversion +/- antiarrhythmic procedure, can exert both primary and secondary preventative effects against atrial tachyarrhythmias. Aggressive prophylactic Maze procedure appeared to be more harmful than beneficial in our study since three patients (20%) developed sinus node dysfunction postoperatively.
The strategy utilized in this study turned out to have limited efficacy in the prevention of thromboembolism, as 11% of the patients developed a thromboembolic event following Fontan conversion. Although whether antiplatelet therapy or anticoagulation is more effective has yet to be elucidated, lifelong thromboprophylaxis seems essential even after the TCPC procedure or Fontan conversion is performed —probably more in older age.
Fontan conversion is a safe and feasible procedure that helps APC patients keep up with primary TCPC patients with respect to hemodynamics and arrhythmia. It is recommended that this procedure be performed before patients become symptomatic. However, the Maze procedure should be limited to those with a history of significant arrhythmia, as it can frequently result in sinus node dysfunction, whereas Fontan conversion itself could lower the risk of arrhythmia.