Effect of ventricular function and volumes on exercise capacity in adults with repaired Tetralogy of Fallot

Impaired Exercise Tolerance in Repaired Tetralogy of Fallot Is Associated With Impaired Biventricular Contractile Reserve: An Exercise-Stress Real-Time Cardiovascular Magnetic Resonance Study

BACKGROUND

Correction of tetralogy of Fallot (cTOF) often results in pulmonary valve pathology and right ventricular (RV) dysfunction. Reduced exercise capacity in cTOF patients cannot be explained by these findings alone. We aimed to explore why cTOF patients exhibit impaired exercise capacity with the aid of a comprehensive cardiopulmonary exercise testing (CPET) and real-time cardiovascular magnetic resonance exercise testing (CMR-ET) protocol.

METHODS

Thirty three cTOF patients and 35 matched healthy controls underwent CPET and CMR-ET in a prospective case-control study. Real-time steady-state free precession cine and phase-contrast sequences were obtained during incremental supine in-scanner cycling at 50, 70, and 90 W. RV and left ventricle (LV) volumes and pulmonary blood flow (Qp) were calculated. Differences of CPET and CMR-ET between cTOF versus controls and correlations between CPET and CMR-ET parameters in cTOF were evaluated statistically for all CMR exercise levels using Mann-Whitney U and Spearman rank-order correlation tests.

RESULTS

CPET capacity was significantly lower in cTOF than in controls. cTOF patients exhibited not only significantly reduced Qp and RV function but also lower LV function on CMR-ET. Higher CPET values in cTOF correlated with higher Qp (Qp 90 W versus carbon dioxide ventilatory equivalent %: R=-0.519, P<0.05), higher LV-end-diastolic volume indexed to body surface area (LV-end-diastolic volume indexed to body surface area at 50 W versus oxygen uptake in % at maximum exercise on CPET R=0.452, P<0.05), and change in LV ejection fraction (EF; LV-EF at 90 W versus Watt %: r=-0.463, P<0.05). No correlation was found with regard to RV-EF. Significant RV-LV interaction was observed during CMR-ET (RV-EF versus LV-EF at 50 W and 70 W: r=0.66, P<0.02 and r=0.52, P<0.05, respectively).

CONCLUSIONS

Impaired exercise capacity in cTOF resulted from a reduction in not only RV, but also LV function. cTOF with good exercise capacity on CPET demonstrated higher LV reserve and pulmonary blood flow during incremental CMR-ET. Apart from RV parameters, CMR-ET-derived LV function could be a valuable tool to stratify cTOF patients for pulmonary valve replacement.

Pulmonary Valve Replacement in Tetralogy of Fallot: An Updated Meta-Analysis

BACKGROUND

The benefits of pulmonary valve replacement (PVR) for pulmonary insufficiency in patients with repaired tetralogy of Fallot are still incompletely understood, and optimal timing remains challenging.

METHODS

We systematically reviewed databases (PubMed/MEDLINE, Embase, Cochrane Central Register of Controlled Trials /Cochrane Controlled Trials Register, ClinicalTrials.gov, Scientific Electronic Library Online, Literatura Latino Americana em Ciências da Saúde, and Google Scholar) and reference lists of relevant articles for studies about PVR in repaired tetralogy of Fallot patients that reported any of the following outcomes: mortality and redo PVR rates, right ventricular (RV) and left ventricular measures, QRS duration, cardiopulmonary exercise test results, or brain natriuretic peptide. In addition to calculating the pooled treatment effects using a random-effects meta-analysis, we evaluated the effect of preoperative measures on PVR outcomes using meta-regressions.

RESULTS

Eighty-four studies involving 7544 patients met the eligibility criteria. Pooled mortality at 30 days, 5 years, and 10 years after PVR was 0.87% (63 of 7253 patients, 80 studies), 2.7% (132 of 4952 patients, 37 studies), and 6.2% (510 of 2765 patients, 15 studies), respectively. Pooled 5- and 10-year redo PVR rates were 3.7% (141 of 3755 patients, 23 studies) and 16.8% (172 of 3035 patients, 16 studies), respectively. The results of the previous meta-analysis could be confirmed. In addition, we demonstrated that after PVR (1) QRS duration, cardiopulmonary exercise test results, and RV and left ventricular measures longitudinal strain do not significantly change; (2) brain natriuretic peptide decreases; and (3) greater indexed RV end-diastolic and end-systolic volumes are associated with lower chances of RV volume normalization after PVR.

CONCLUSIONS

This updated meta-analysis provides evidence about the benefits of PVR.

Long-term follow-up in adults after tetralogy of Fallot repair

Background

Tetralogy of Fallot (ToF) is the most common cyanotic congenital heart disease and the population of ToF repair survivors is growing rapidly. Adults with repaired ToF develop late complications. The aim of this study was to describe and analyze long-term follow-up of patients with repaired ToF.

Methods

This is a retrospective cohort study. Consecutive 83 patients with repaired ToF who did not undergo pulmonary valve replacement were included. Mean age of all patients was 30.5 ± 10.7. There were 49 (59%) male. Patients were divided into two groups according to the time since the repair (< 25 years and ≥ 25 years). The electrocardiographic (ECG), cardiopulmonary exercise testing (CPET), echocardiographic and cardiac magnetic resonance (CMR) data were reviewed retrospectively.

Results

In CPET values were not significantly different in the two groups. In CMR volumes of left and right ventricles were not significantly different in the two groups. There were no differences between the groups in ventricular ejection fraction, mass of ventricles, or pulmonary regurgitation fraction. Among all the patients, ejection fraction and left and right ventricle mass, indexed pulmonary regurgitation volume measured by CMR did not correlate with the time since repair. In ECG among all the patients, ejection fraction of the RV, measured in CMR, negatively correlated with QRS duration (r = − 0.43; p < 0.001). There was a positive correlation between QRS duration and end diastolic volume of the RV (r = 0.30; p < 0.02), indexed end diastolic volume of the RV (r = 0.29; p = 0.04), RV mass (r = 0.36; p < 0.001) and left ventricle mass (r = 0.26; p = 0.04).

Conclusion

Long-term survival and clinical condition after surgical correction of ToF in infancy is generally good and the late functional status in ToF – operated patients could be excellent up to 25 years after the repair. QRS duration could be an utility and easy factor to assessment of right ventricular function.

Trial registration

The study protocol was approved by the local Ethics Committee. Each participant provided informed consent to participate in the study (license number 122.6120.88.2016 from 28.04.2016).