Results of exercise testing at a mean age of 10 years after neonatal arterial switch operation

Exercise Capacity After Arterial Switch Operation in Patients with D-Transposition of Great Arteries: Does the Coronary Artery Anatomy Matter?

Variant coronary anatomy (VarCA) is frequent in D-Transposition of the great arteries (d-TGA). There are a paucity of data on the effect of the VarCA on the exercise capacity (XC) in patients with repaired d-TGA. This retrospective study included patients with d-TGA who underwent an arterial switch operation (ASO) and had at least one cardiopulmonary exercise test (CPET). Data from the treadmill CPET and simultaneously performed spirometry were collected. The parameters of CPET were compared between patients with usual anatomy vs. VarCA. Longitudinal changes in XC in patients with ASO were also analyzed. A total of 44 patients with either usual coronary anatomy (n = 27, 61%) or VarCA (n = 17, 39%) met inclusion criteria. There was no significant difference in oxygen consumption (%VO₂) at initial CPET (104 vs. 100%, p = 0.53) between the two groups. Abnormal %VO₂ (< 85%) was uncommon in both groups (n = 2, 7.4% vs. n = 4; 23.5%; p = ns). For longitudinal changes, there was no significant decline in %VO₂ in either group: (i) usual coronary anatomy (n = 15, median follow-up 4.8 years, %VO₂ 111 vs. 108%; p = 0.306) and (ii) VarCA (n = 10, median follow-up 6.6 years, %VO₂ 106 vs. 92%; p = 0.441). Spirometry was abnormal in 25 (59.5%) patients [restrictive (n = 8, 19.0%), obstructive (n = 15, 35.7%), and mixed (n = 2, 4.8%)] butabnormal spirometry had no impact on the XC. Patients with d-TGA who underwent neonatal ASO uniformly exhibited good XC without any longitudinal decline on medium-term follow-up, regardless of coronary artery anatomy. Although frequent (60%), abnormal spirometry was not associated with reduced exercise capacity.

Identifying Subclinical Coronary Abnormalities and Silent Myocardial Ischemia After Arterial Switch Operation

The incidence of late coronary complications is reported around 8% after arterial switch operation (ASO) for d-transposition of the great arteries, but the affected patients are usually asymptomatic. Exercise stress test (EST) and myocardial perfusion imaging (MPI) are common non-invasive modalities to screen for silent myocardial ischemia, but their diagnostic reliability in children after ASO is unclear. We retrospectively reviewed asymptomatic patients following ASO with EST, MPI, and coronary imaging studies (CIS) and examined the reliability of each test in identifying abnormal coronary lesions responsible for myocardial ischemia. Thirty-seven asymptomatic patients (24 males; ages 12.7 ± 3.7 years) had EST, in which 27 and 33 patients also underwent MPI and CIS, respectively. Exercise capacity was comparable to the age- and sex-matched 37 controls. In seven patients with angiographically proven moderate to severe coronary abnormalities, only two patients had positive EST and/or MPI, and five patients were negative including one patient who later developed exercise-induced cardiac arrest due to severe proximal left coronary artery stenosis. Two patients with positive EST or MPI showed no corresponding coronary abnormalities by CIS. Occurrence of acquired late coronary abnormalities did not correlate with the original coronary anatomy or initial surgical procedures. There is no single reliable method to identify the risk of myocardial ischemia after ASO. Although CIS are regarded as a gold standard, multidisciplinary studies are essential to risk-stratify the potential life-threatening coronary lesions after ASO in children.

Left ventricular function and exercise capacity after arterial switch operation for transposition of the great arteries: a systematic review and meta-analysis

BACKGROUND

The arterial switch operation for transposition of the great arteries was initially believed to be an anatomical correction. Recent evidence shows reduced exercise capacity and left ventricular function in varying degrees in the long term after an arterial switch operation.

OBJECTIVE

To perform a meta-analysis on long-term exercise capacity and left ventricular ejection fraction after an arterial switch operation.

METHODS

A literature search was performed to cover all studies on patients who had undergone a minimum of 6 years of follow-up that reported either left ventricular ejection fraction, peak oxygen uptake, peak workload, and/or peak heart rate. A meta-analysis was performed if more than three studies reported the outcome of interest.

RESULTS

A total of 21 studies reported on the outcomes of interest. Oxygen uptake was consistently lower in patients who had undergone an arterial switch operation compared with healthy controls, with a pooled average peak oxygen uptake of 87.5±2.9% of predicted. The peak heart rate was also lower compared with that of controls, at 92±2% of predicted. Peak workload was significantly reduced in two studies. Pooled left ventricular ejection fraction was normal at 60.7±7.2%.

CONCLUSION

Exercise capacity is reduced and left ventricular ejection fraction is preserved in the long term after an arterial switch operation for transposition of the great arteries.

Functional Capacity in Congenital Heart Disease: A Systematic Review and Meta-Analysis

Background

Children and adolescents with congenital heart disease often have alterations in their exercise capacity that can be evaluated by various functional testing.

Objective

To evaluate the functional capacity of children and adolescents with congenital heart disease (CHD) with systematic review and meta-analyses.

Methods

The review included observational studies, data from the first evaluation of randomized clinical trials or observational follow-up periods after clinical trials which evaluated functional capacity by cardiopulmonary exercise test, stress testing, six-minute walk test or step test, in children and adolescents with CHD, aged between six and 18 years, and comparisons with healthy controls in the same age group. The quantitative assessment was performed by meta-analysis, by comparing the maximal oxygen consumption (VO₂max) of children and adolescents with CHD and respective control groups.

Results

Twenty-five of 2.683 studies identified in the search met the inclusion criteria. The VO₂max measurement showed that patients with CHD have a decrease of 9.31 ml/Kg/min (95% CI. -12.48 to -6.13; I², 94.3%, P for heterogeneity < 0.001) compared with the control group. The meta-analysis of the data of maximum heart rate (HR) reached during cardiopulmonary test and stress testing, retrieved from 18 studies, showed a HR value of -15.14 bpm (95% CI. -20.97 to -9.31; I², 94.3%, P for heterogeneity < 0.001) compared with the control group.

Conclusion

Children and adolescents with CHD have lower VO₂max and HR compared to controls.

Exercise Performance in Patients with D-Loop Transposition of the Great Arteries After Arterial Switch Operation: Long-Term Outcomes and Longitudinal Assessment

The first patients to undergo a successful arterial switch operation (ASO) for d-transposition of the great arteries (D-TGA) are now entering their fourth decade of life. Past studies of ASO survivors' exercise function have yielded conflicting results. We therefore undertook this study to describe the current function of ASO survivors, to identify factors related to inferior exercise performance and to determine whether their exercise function tends to deteriorate over time. A retrospective cohort study was designed examining all patients with D-TGA after the ASO who underwent comprehensive cardiopulmonary exercise testing (CPET). Patients with palliative surgery prior to ASO, ventricular hypoplasia or severe valvar dysfunction were excluded from the study. Data from CPETs in which the peak respiratory exchange ratio was <1.09 were also excluded. We identified 113 patients who met entry criteria and had 186 CPX at our institution between 1/2002 and 1/2013; 41 patients had at least 2 qualifying CPX. Mean age at the time of the initial test was 17 ± 1 year. Peak oxygen consumption (VO2) averaged 84 ± 2 % predicted. Peak VO2 was lower among patients with repaired ventricular septal defects (82 ± 4 vs. 86 ± 3 % predicted; p < 0.05) and among patients with ≥ moderate right-sided obstructive lesions (77 ± 5 vs. 87 ± 3 % predicted; p < 0.05). Surgery prior to 1991 was also associated with a lower peak VO2 (81 ± 3 vs. 87 ± 3 % predicted; p < 0.01). The mean % predicted peak heart rate was 92 ± 1 %, with no significant difference between any of the subgroups. Non-diagnostic exercise-induced STT changes developed in 10 patients (12 studies). In the subgroup with at least 2 exercise tests, the annual decline in % predicted peak VO2 was quite slow (-0.3 % points/year; p < 0.01 vs. expected normal age-related decline). The exercise capacity of ASO survivors is well preserved and is only mildly reduced compared to normal subjects. Moreover, there is only a slight deterioration in exercise capacity over time. VSD repair, residual right-sided obstructive lesions, and earlier surgical era are associated with worse exercise performance. Peak heart rate was preserved with no significant change in follow up testing.

Coronary artery problems late after arterial switch operation for transposition of the great arteries

BACKGROUND

The incidence of late coronary artery abnormalities after arterial switch operation (ASO) for d-loop transposition of the great arteries may be underestimated.

METHODS AND RESULTS

We retrospectively reviewed coronary artery morphology in 40 of 97 patients who survived the first year after ASO. Seven asymptomatic patients developed significant late coronary artery abnormalities. One patient died suddenly at home with severe left coronary artery (LCA) ostial stenosis at age 3.8 years. The second patient collapsed during exercise at age 9.6 years due to ventricular fibrillation and severe LCA ostial stenosis despite prior negative exercise stress test (EST) and myocardial perfusion imaging (MPI). The third patient was found to have moderate ostial stenosis of the LCA with negative EST and MPI. The fourth patient with exercise-induced ST-T depression and myocardial perfusion defect was shown to have complete LCA occlusion with collateral vessel formation. Three other patients had complete proximal obliteration of either of the coronary arteries with collateral supply. An additional 4 asymptomatic patients had trivial-mild narrowing of the LCA on routine selective coronary angiogram.

CONCLUSIONS

Incidence of late coronary stenosis or occlusion was not infrequent after ASO (11.3%) and presented usually without preceding symptoms and often after negative non-invasive screening. We advocate routine coronary imaging in all patients after ASO before they participate in competitive sports.

Comparison of late results of arterial switch versus atrial switch (mustard procedure) operation for transposition of the great arteries

Two decades after surgery for transposition of the great arteries, the clinical status, cardiac function, cardiorespiratory performance, and neurohormonal activity of patients who underwent either atrial switch (Mustard) operations or arterial switch operations (ASOs) were compared. Sixty-two patients with simple transposition of the great arteries who underwent either Mustard (n = 34) or ASO (n = 28) procedures were included in this cross-sectional study. Following the same study protocol, clinical workup including echocardiography, stress testing, and blood work was completed for all patients. Mean ages in the 2 groups were comparable, at 20.6 ± 2.1 and 20.6 ± 3.4 years in the ASO and Mustard groups, respectively. All ASO patients were in New York Heart Association class I, whereas 59% of Mustard patients were in class II or III. Peak oxygen uptake was higher in ASO patients (percentage of predicted 80% vs 69%, p <0.01). Compared with healthy subjects, the mean Tei index for systemic ventricle was high in the 2 groups, but this parameter was significantly higher in Mustard than ASO patients (0.60 ± 0.16 vs 0.47 ± 0.14, p <0.01). The median plasma N-terminal pro-brain natriuretic peptide level in ASO patients was within the normal range, but the Mustard group had significantly higher levels (42 ng/ml [range 18 to 323] vs 172 ng/ml [range 26 to 1,018], p <0.0001). In conclusion, this cross-sectional assessment 2 decades after surgery reveals better clinical status in patients who underwent ASO compared with Mustard patients. This holds in terms of cardiac function, cardiorespiratory performance, and neurohormonal activity.

Declining aerobic capacity of patients with arterial and atrial switch procedures

BACKGROUND

Patients with transposition of the great arteries corrected by an atrial switch procedure are believed to have a worse physical outcome than patients with an arterial switch procedure correction. This study aimed to compare exercise data for patients with the two surgical methods.

METHODS

This study retrospectively analyzed exercise treadmill test results for 7- to 17-year-old patients who underwent either an atrial switch procedure (n=45) or an arterial switch procedure (n=44). The results were compared with reference material.

RESULTS

Both groups showed significantly less aerobic capacity than healthy subjects. The atrial switch patients achieved 69% of reference status, and the arterial switch patients achieved 82%. A gradual decline in exercise capacity with increasing age was shown for patients with atrial switch circulation (p<0.0001). No significant difference was found for the arterial switch group (p=0.319).

CONCLUSIONS

Significantly less aerobic capacity was found in atrial and arterial switch patients than in healthy subjects. A decline in aerobic capacity with increasing age was found in the atrial switch patients. However, the small number of teenagers in the arterial switch group limits the ability to be conclusive. The results indicate that chronotropic incompetence may be one of the reasons for diminishing capacity. The decline in exercise performance leads the authors to recommend regular follow-up exercise testing.

Physical Activity Patterns of Children After Neonatal Arterial Switch Operation

BACKGROUND

Physical inactivity is a major atherosclerosis risk factor. The exercise tolerance is usually excellent after neonatal arterial switch operation, but those patients in whom coronary anomalies remain the main late complication, risk developing atherosclerotic coronary disease owing to perceived physical activity restrictions.

METHODS

We investigated physical activity patterns of 52 unselected children 7 to 14 years after neonatal arterial switch operation for transposition of the great arteries by 24-hour continuous heart rate monitoring. The percentage of heart rate reserve was used to measure the amounts of activities. Comparisons were made with 35 children with repaired atrial or ventricular septal defect and with 127 age-matched healthy children.

RESULTS

Children after arterial switch operation accumulated 167.3 +/- 70.6, 25.3 +/- 12.9, and 15.7 +/- 11.3 minutes a day (mean +/- SD) of light, moderate, and vigorous physical activities, respectively. At the same activity levels, children with repaired septal defect accumulated 165.2 +/- 82.2, 26.2 +/- 11.7, and 16.2 +/- 9.1 minutes a day, and their healthy peers 164.8 +/- 74.5, 31.8 +/- 13.9, and 21.9 +/- 11.3 minutes a day. Both cardiac groups were significantly less active than the control group when considering moderate (p = 0.026) and vigorous activities (p = 0.006). Only 19% and 27% of the children after arterial switch operation engaged, respectively, in more than 30 minutes a day of moderate activity and 20 minutes a day of vigorous activity.

CONCLUSIONS

Children after arterial switch operation, just like other cardiac children, do not meet the guidelines for physical activity. We should encourage regular physical activity to offset adult sedentary behavior and to prevent atherosclerotic cardiovascular disease in those patients whose long-term function of the coronary arteries remains a matter of concern.