Echocardiography and MRI parameters associated with exercise capacity in patients after the arterial switch operation.

BACKGROUND: The arterial switch operation (ASO) for transposition of the great arteries has excellent survival, but a substantial number of patients suffer from a reduced exercise capacity. The goal of this study was to identify imaging parameters associated with a reduced exercise capacity in patients after ASO. METHODS: A retrospective analysis was performed of ASO patients who underwent cardiopulmonary exercise testing (CPET) between 2007 and 2017. Reduced exercise performance was defined as a reduced workload peak (Wpeak) with Z-score <-2 or a peak oxygen uptake indexed for weight (VO2peak/kg) with Z-score <-2. Data on echocardiography and cardiac magnetic resonance performed within 1 year of the CPET were collected for comparison. RESULTS: A total of 81 ASO patients (age 17±7 years) were included. Reduced exercise performance was found in 22 patients (27%) as expressed by either a reduced Wpeak and/or a reduced VO2peak/kg. Main pulmonary artery gradient and tricuspid regurgitation gradient by echocardiography were found to be associated with reduced Wpeak (p=0.031; p=0.020, respectively). The main pulmonary artery gradient and tricuspid regurgitation gradient by echocardiography were found to be associated with reduced VO2peak/kg (p=0.009; p=0.019, respectively). No left ventricular parameters were found to be associated with abnormal exercise performance. CONCLUSION: This study demonstrates that ASO patients frequently experience reduced exercise capacity. Echocardiographic evidence of main pulmonary artery stenosis and increased right ventricular pressure were associated with reduced exercise capacity, and are therefore key to monitor during serial follow-up of ASO patients.

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.

Sudden Death Due to Coronary Artery Lesions Long-term After the Arterial Switch Operation: A Systematic Review.

BACKGROUND: The arterial switch operation (ASO) is the preferred procedure for children with dextrotransposition of the great arteries or Taussig-Bing anomaly. Short- as well as long-term outcome of ASO are excellent, but coronary artery stenoses are reported as a common long-term complication. It has been hypothesized that these might result in sudden cardiac death late after ASO. METHODS: A systematic search of PubMed and EMBASE was conducted to evaluate sudden cardiac death because of coronary complications late after ASO. Data on patients surviving ≥ 5 years post-ASO were collected from selected studies, corrected for duplicate data, and analyzed. RESULTS: After duplicate data correction 52 studies remained for data analysis. Among the 8798 survivors with follow-up, 27 patients died ≥ 5 years post-ASO (0.3%). Of these patients, 10 were known with relevant residual lesions. Five late deaths were sudden, possibly from a cardiac cause. None of the late sudden deaths were confirmed to be coronary-related. CONCLUSIONS: Sudden cardiac death in asymptomatic patients as a result of coronary artery stenosis or occlusion is extremely rare, with 5 possible cases and no proven cases of coronary artery-related sudden cardiac death in 8798 patients with 66,450 patient follow-up years. Therefore, routine coronary imaging of asymptomatic, single-stage ASO patients is not justified.

Main pulmonary artery area limits exercise capacity in patients long-term after arterial switch operation.

OBJECTIVES: Despite excellent survival in patients after the arterial switch operation, reintervention is frequently required and exercise capacity is decreased in a substantial number of patients. This study relates right-sided imaging features in patients long-term after the arterial switch operation to exercise capacity and ventilatory efficiency to investigate which lesions are functionally important. METHODS: Patients operated in the UMC Utrecht, the Netherlands (1976-2001) and healthy controls underwent cardiac magnetic resonance imaging and cardiopulmonary exercise testing within 1 week. We measured main, left, and right pulmonary artery cross-sectional areas, pulmonary blood flow distribution, peak oxygen uptake, and minute ventilation relative to carbon dioxide elimination. RESULTS: A total of 71 patients (median age, 20 [12-35] years, 73% were male) and 21 healthy controls (median age, 26 [21-35] years, 48% were male) were included. Main, left, and right pulmonary artery areas were decreased compared with controls (190 vs 269 mm(2)/m(2), 59 vs 157 mm(2)/m(2), 98 vs 139 mm(2)/m(2), respectively, all P < .001); however, pulmonary blood flow distribution was comparable (P = .722). Peak oxygen uptake and minute ventilation relative to carbon dioxide elimination were 88% ± 20% and 23.7 ± 3.8, respectively, with 42% and 1% of patients demonstrating abnormal results (≤ 84% and ≥ 34, respectively). The main pulmonary artery area significantly correlated with peak oxygen uptake (r = 0.401, P = .001) and pulmonary blood flow distribution with minute ventilation relative to carbon dioxide elimination (r = -0.329, P = .008). Subanalysis (<18, 18-25, >25 years) showed that the main pulmonary artery area was smaller in older age groups. In multivariable analysis, the main pulmonary artery area was independently associated with peak oxygen uptake (P = .032). CONCLUSIONS: In adult patients after the arterial switch operation, narrowing of the main pulmonary artery is a common finding and is the main determinant of limitation in functional capacity, rather than pulmonary branch stenosis.