Short-Term Change of Exercise Capacity in Patients with Pulmonary Valve Replacement after Tetralogy of Fallot Repair

Left ventricular strain derived from cardiac magnetic resonance can predict outcomes of pulmonary valve replacement in patients with repaired tetralogy of Fallot

Purpose

Several adults with repaired tetralogy of Fallot (rToF) undergo pulmonary valve replacement (PVR) to reduce the right ventricular volume and retain right ventricular function. However, there is currently no consensus on the ideal time for PVR surgery in asymptomatic patients with rTOF with pulmonary regurgitation (PR). Clinical outcomes after PVR are also indeterminate. Recently, myocardial strain and strain rate derived from cardiac magnetic resonance (CMR) feature tracking were found to be more sensitive to right ventricular dysfunction than conventional parameters and therefore may add prognostic value in patients with rToF. We aimed to analyze whether pre-PVR left ventricular (LV) strain and strain rate detected by CMR feature tracking are associated with midterm outcomes after PVR in patients with rToF.

Methods

Seventy-eight asymptomatic patients with rToF who required PVR due to moderate or severe PR were prospectively enrolled between January 2014 and June 2020. CMR cine sequences were obtained, and feature tracking parameters were measured preoperatively. Adverse events were documented during the follow-up. Receiver operating characteristic analysis was performed to determine the cutoff value. Kaplan–Meier curves were drawn with log-rank statistics; moreover, univariate and multivariate Cox proportional hazards regression analyses and Harrel C-indices were analyzed.

Results

During 3.6 ± 1.8 years of follow-up, 25 adverse events were recorded. Kaplan–Meier survival curves and univariate Cox analysis verified that patients with significantly reduced radial strain (RS), circumferential strain (CS), longitudinal strain (LS), RS rate at systole and diastole (RSRs and RSRe), and circumferential and LS rates at diastole (CSRe and LSRe) had worse event-free survival. After multivariate correction, only LS and LSRe remained significantly associated with adverse outcomes (hazard ratio = 1.243 [1.083–1.428] and 0.067 [0.017–0.258], respectively, all p < 0.05). The cutoff values of LS and LSRe were −12.30 (%) and 1.07 (s–1), respectively.

Conclusion

The LV strain and strain rate prior to PVR are important prognostic factors for adverse events after PVR in rToF.

Comparison of Predicted Exercise Capacity Equations in Adult Korean Subjects

BACKGROUND

Maximal oxygen uptake (VO₂ max) is a useful index to assess exercise capacity. However, there is no reference value for Koreans. This study aimed to compare actual VO₂ max and predicted VO₂ max using exercise capacity equations in Korean subjects.

METHODS

This retrospective study enrolled 383 patients who underwent cardiopulmonary exercise test (CPET) with incremental maximal cycle ergometer test at Asan Medical Center from January 2020 to May 2021. Stage 1 and 2 lung cancer patients with normal lung function and healthy persons of 50 subjects who had maximal CPET were analyzed.

RESULTS

The subjects were aged 65 ± 13 years and predominantly male (74%). CPET results were as follows: absolute VO₂ max, 1.2 ± 0.3 L/min; body weight referenced VO₂ max, 20 ± 3.9 mL/kg/min; peak work rate, 94 ± 24 watts; peak heart rate, 142 ± 21 bpm; peak O₂ pulse, 10 ± 3 mL/beat; minute ventilation, 59 ± 14 L/min; peak respiratory rate, 34 ± 6 breaths per minute; and peak breathing reserve, 41 ± 18%. There was significant discordance between the measured and predicted absolute VO₂ max using the Jones, Hansen, and Wasserman prediction equations developed for Caucasian population (P < 0.001). Agreement using Bland-Altman test between true and predicted absolute VO₂ max was the best in Chinese equation (-0.03, 2SD = 0.55) compared to Jones (0.42, 2SD = 1.07), Hansen (0.44, 2SD = 0.86), and Wasserman (0.42, 2SD = 0.86) equations.

CONCLUSION

The reference value and prediction equation from studies including primarily Caucasians may not be appropriate for Koreans. Since the mean difference is the lowest in Chinese equation, the Chinese equation might be used for the Korean adult population.

Repair of tricuspid valve with pulmonary valve replacement in repaired tetralogy of fallot

Objectives: We aimed to investigate the outcome of tricuspid valve repair (TVR) performed concomitantly with pulmonary valve replacement in repaired tetralogy of Fallot (TOF) patients. Design: This retrospective study included all patients who underwent pulmonary vale replacement from 2000 to 2016 after TOF correction. TVR patient data were compared to those of patients who underwent pulmonary vale replacement alone. Results: Thirty-eight patients were enrolled. The degree of tricuspid regurgitation was significantly decreased after operation in the TVR group. Tricuspid valve annulus and annuloectasia before operation did not vary between groups (21.1 ± 6.3 and 41.4% in no TVR vs. 21.3 ± 4.8 and 52.6% in TVR). However pre-operative right ventricular volumes were larger in the TVR group. Normal tricuspid valve coaptation (body to body) was observed less frequently in the TVR group than in the other group (52.6% vs. 93.1%, p < .001). Pre-operative tricuspid regurgitation had a linear correlation with right ventricular volume, but not with tricuspid annulus size. Conclusion: Tricuspid annulus diameter decreased significantly regardless of TVR. Abnormal coaptations were observed more in patients group and the degree of pre-operative tricuspid regurgitation was linearly correlated with right ventricular volume rather than tricuspid annulus size.