Elsevier

American Heart Journal

Volume 230, December 2020, Pages 82-92
American Heart Journal

Clinical Investigations
Cardiac resynchronization therapy improves the ventricular function of patients with Fontan physiology

https://doi.org/10.1016/j.ahj.2020.09.018Get rights and content

Background

Past studies have not detected consistent improvement in ventricular function (VFxn) following initiation of cardiac resynchronization therapy (CRT) in Fontan patients. However, these studies used qualitative assessments of VFxn and/or quantitative assessments of VFxn that rely upon anatomic and/or geometric assumptions that may not be valid in patients with single ventricles. To address this, we used quantitative indices of global VFxn (dP/dtic and the Tei index) that are not encumbered by the limitations associated with the indices used in previous studies of CRT in Fontan patients.

Methods

Patients with Fontan physiology who had received CRT therapy from 2004 to 2019 were included in the study. They were compared to a concurrent group of Fontan patients who had received standard dual-chamber pacemakers (DCPMs).

Results

VFxn was assessed at 3 time points: prior to, shortly after, and late after initiation of pacemaker therapy. Prior to initiation of pacemaker therapy, VFxn of the CRT patients tended to be worse than that of the DCPM patients. For both groups, VFxn appeared to be stable or slightly improved shortly after initiation of pacemaker therapy. In the CRT group, VFxn improved significantly between early and late follow-up. In contrast, VFxn in DCPM patients tended to decline during this period. Changes in VFxn correlated with concurrent changes in New York Heart Association classification.

Conclusions

Quantitative assessments of VFxn using indices not confounded by complex cardiac anatomy, segmental wall motions abnormalities, or inappropriate geometric assumptions revealed that CRT in Fontan patients is associated with preservation or improvement VFxn compared to standard DCPM. Changes in VFxn correlate with concurrent changes in New York Heart Association classification.

Section snippets

Patients

Patient records at Boston Children's Hospital were queried from 2004 (when our echocardiography laboratory converted from analog to digital technology) to 2019. Patients with single ventricles palliated via the Fontan procedure who had ventricular pacemakers implanted (before, during, or after Fontan completion) and also had pre- and postdevice echocardiographic studies that permitted measurement of dP/dtic and the Tei index were included in the study. Patients who underwent CRT device

Patients

During the period under study, 23 patients with Fontan physiology received CRT. Of these, 17 patients had echocardiographic studies that permitted determination of the dP/dtic and the Tei index at all 3 time points. These 17 patients were the focus of this study. One patient received a heart transplant 2 months after the initiation of CRT, and another transferred care to another institution 3 months after initiation of CRT. These 2 patients therefore did not have a Late-Post measurement, but

Discussion

Our study differs from previous studies on the effect of CRT on patients with Fontan physiology in that the indices of ventricular function that were used were quantitative and were independent of ventricular anatomy or geometry. Our methodology can therefore, theoretically, provide more objective and reliable data concerning the effect of CRT in this population.

Not surprisingly, we found that the indices of ventricular function of both patient groups tended to be lower than those of Fontan

Limitations

This was a single-center, retrospective study. Consequently, the number of patients included in this study was small. Moreover, the indications for CRT implantation and the follow-up of patients receiving CRT or DCPM were not protocolized. Patients who were lost to follow-up or who did not have ongoing care at our institution following the initiation of pacemaker therapy could not be included in the study. In addition, although the time intervals between the echocardiographic measurements were

Conclusions

Quantitative assessments of ventricular function, using indices that are not confounded by complex cardiac anatomy, segmental wall motions abnormalities, or potentially inappropriate geometric assumptions, revealed that CRT is associated with preservation or improvement of ventricular function compared to standard DCPM in Fontan patients with high-grade AV block. For future studies of the effect of CRT upon the ventricular function of patients with Fontan circulations, these indices may offer

One-sentence summary

Assessments of ventricular function using quantitative echocardiographic indices that are not confounded by complex ventricular anatomy or potentially invalid geometric assumptions revealed that cardiac resynchronization therapy is associated with an improvement in ventricular function compared to standard dual-chamber pacemaker therapy in patients with Fontan physiology.

Declaration of competing interests

None declared.

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    Declarations of interest: None.

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