Leadless pacemaker implant guided by intracardiac echocardiography in a patient after Mustard repair.

This case report describes a successful leadless pacemaker implant (Micra VR Medtronic, Inc, Minneapolis, MN) in a 48-year-old patient with a history of Mustard repair. Twenty-one years after dual-chamber pacemaker implant, both conventional leads became dysfunctional. Lead extraction was refused by the patient and the subclavian vein was obstructed. A leadless pacemaker was selected as an alternative. Intracardiac echocardiography allowed the safe introduction of the delivery system into the nonsystemic left ventricle. Four months after implant, the pacing parameters are stable and the patient is without new complaints. A leadless pacemaker could be considered in patients with complex grown-up congenital heart disease (GUCH).

The natural and unnatural history of the Mustard procedure: long-term outcome up to 40 years.

AIMS: To describe long-term survival, clinical outcome and ventricular systolic function in a longitudinally followed cohort of patients after Mustard repair for transposition of the great arteries (TGA). There is serious concern about the long-term outcome after Mustard repair. METHODS AND RESULTS: This longitudinal single-centre study consisted of 91 consecutive patients, who underwent Mustard repair before 1980, at age <15 years, and were evaluated in-hospital every 10 years. Survival status was obtained of 86 patients. Median follow-up was 35 (IQR 34-38) years. Cumulative survival was 84% after 10 years, 80% after 20 years, 77% after 30 years, and 68% after 39 years. Cumulative survival free of events (i.e. heart transplantation, arrhythmias, reintervention, and heart failure) was 19% after 39 years. Reinterventions were mainly required for baffle-related problems. Supraventricular and ventricular arrhythmias occurred in 28 and 6% of the patients, respectively. Pacemaker and/or ICD implantation was performed in 39%. Fifty survivors participated in the current in-hospital investigation including electrocardiography, 2D-echocardiography, cardiopulmonary-exercise testing, NT-proBNP measurement, Holter monitoring, and cardiac magnetic resonance. Right ventricular systolic function was impaired in all but one patient at last follow-up, and 14% developed heart failure in the last decade. NT-proBNP levels [median 31.6 (IQR 22.3-53.2) pmol/L] were elevated in 92% of the patients. Early postoperative arrhythmias were a predictor for late arrhythmias [HR 3.8 (95% CI 1.5-9.5)], and development of heart failure [HR 8.1 (95% CI 2.2-30.7)]. Also older age at operation was a predictor for heart failure [HR 1.26 (95% CI 1.0-1.6)]. CONCLUSION: Long-term survival after Mustard repair is clearly diminished and morbidity is substantial. Early postoperative arrhythmias are a predictor for heart failure and late arrhythmias.

Mustard baffle obstruction and leak - How successful are percutaneous interventions in adults?

Atrial switch operations for D-Transposition of the great arteries (D-TGA) were performed until the late 20th century. These patients have substantial rates of re-operation, particularly for baffle related complications. This study sought to analyze the efficacy of percutaneous transcatheter intervention (PTI) for baffle leak and/or stenosis in adult atrial switch patients. Adult patients with a prior atrial switch operation who underwent heart catheterization (2002-2014) at a tertiary adult congenital heart disease referral center were retrospectively analyzed. In 58 adults (30 ± 8 years, 75% men, 14% New York Heart Association (NYHA) functional class ≥2) who underwent 79 catheterizations, PTI was attempted in 50 (baffle leak (n = 10, 20%), stenosis (n = 27, 54%), or both (n = 13, 26%)). PTI was successful in 45 and 5 were referred for surgery due to complex anatomy. A total of 40 bare metal stents, 18 covered stents, 16 occlusion devices, 2 angioplasties, and 1 endovascular graft were deployed. In isolated stenosis, there was improvement in NYHA functional class after PTI (8 vs. 0 patients were NYHA FC > 2, p = 0.004), which was matched by improvement in maximal oxygen consumption on exercise testing (VO2) (25.1 ± 5.4 mL/kg/min vs. 27.9 ± 9 mL/kg/min, p = 0.03). There were no procedure-related deaths or emergent surgeries in this cohort. This single-center cohort is the largest reported series of adult atrial switch operation patients who have undergone PTI for baffle stenosis and/or leak. We demonstrate that PTI with an expert multi-disciplinary team is a safe and effective alternative to surgery in adult patients with an atrial switch operation.

Common genetic variants improve risk stratification after the atrial switch operation for transposition of the great arteries.

BACKGROUND: Clinical factors are used to estimate late complication risk in adults after atrial switch operation (AtrSO) for transposition of the great arteries (TGA), but heterogeneity in clinical course remains. We studied whether common genetic variants are associated with outcome and add value to a clinical risk score in TGA-AtrSO patients. METHODS AND RESULTS: This multicenter study followed 133 TGA-AtrSO patients (aged 28 [IQR 24-35] years) for 13 (IQR 9-16) years and examined the association of genome-wide single-nucleotide polymorphisms (SNPs) with a composite endpoint of symptomatic ventricular arrhythmia, heart failure hospitalization, ventricular assist device implantation, heart transplantation, or mortality. Thirty-two patients (24%) reached the endpoint. The genome-wide association study yielded one genome-wide significant (p < 1 × 10-8) locus and 18 suggestive loci (p < 1 × 10-5). A genetic risk score constructed on the basis of independent SNPs with p < 1 × 10-5 was associated with outcome after correction for the clinical risk score (HR = 1.26/point increase [95%CI 1.17-1.35]). Risk stratification improved with a combined risk score (clinical score + genetic score) compared to the clinical score alone (p = 2 × 10-16, C-statistic 0.95 vs 0.85). In 51 patients with a clinical intermediate (5-20%) 5-year risk of events, the combined score reclassified 32 patients to low (<5%) and 5 to high (>20%) risk. Stratified by the combined score, observed 5-year event-free survival was 100%, 79% and 31% for low, intermediate, and high-risk patients, respectively. CONCLUSIONS: Common genetic variants may explain some variation in the clinical course in TGA-AtrSO and improve risk stratification over clinical factors alone, especially in patients at intermediate clinical risk. These findings support the hypothesis that including genetic variants in risk assessment may be beneficial.

Catheter Ablation of Hemodynamically Unstable Ventricular Tachycardia in a Patient with Dextro - Transposition of the Great Arteries and Mustard's Repair.

INTRODUCTION: A patient with D-TGA and surgical repair (Mustard's procedure) presented with appropriate ICD shocks due to monomorphic ventricular tachycardia, refractory to antiarrhythmic medications. METHODS AND RESULTS: The patient underwent an electrophysiological study and catheter ablation for the VT. Substrate and pace mapping techniques, with the help of an electroanatomical mapping system, was used to localize and ablate the tachycardia successfully. CONCLUSIONS: In patients with D-TGA and Mustard's repair, scar tissue resulting from VSD repair can act as a substrate for recurrent VT. Catheter ablation of VT is useful in management of VT that occurs despite antiarrhythmic therapy and/or when it is unstable.

Clinical Course Long After Atrial Switch: A Novel Risk Score for Major Clinical Events.

Background Patients with transposition of the great arteries corrected by an atrial switch operation experience major clinical events during adulthood, mainly heart failure (HF) and arrhythmias, but data on the emerging risks remain scarce. We assessed the risk for events during the clinical course in adulthood, and provided a novel risk score for event-free survival. Methods and Results This multicenter study observed 167 patients with transposition of the great arteries corrected by an atrial switch operation (61% Mustard procedure; age, 28 [interquartile range, 24-36] years) for 13 (interquartile range, 9-16) years, during which 16 (10%) patients died, 33 (20%) had HF events, defined as HF hospitalizations, heart transplantation, ventricular assist device implantation, or HF-related death, and 15 (9%) had symptomatic ventricular arrhythmias. Five-year risk of mortality, first HF event, and first ventricular arrhythmia increased from 1% each at age 25 years, to 6% (95% CI, 4%-9%), 23% (95% CI, 17%-28%), and 5% (95% CI, 2%-8%), respectively, at age 50 years. Predictors for event-free survival were examined to construct a prediction model using bootstrapping techniques. A prediction model combining age >30 years, prior ventricular arrhythmia, age >1 year at repair, moderate or greater right ventricular dysfunction, severe tricuspid regurgitation, and mild or greater left ventricular dysfunction discriminated well between patients at low (<5%), intermediate (5%-20%), and high (>20%) 5-year risk (optimism-corrected C-statistic, 0.86 [95% CI, 0.82-0.90]). Observed 5- and 10-year event-free survival rates in low-risk patients were 100% and 97%, respectively, compared with only 31% and 8%, respectively, in high-risk patients. Conclusions The clinical course of patients undergoing atrial switch increasingly consists of major clinical events, especially HF. A novel risk score stratifying patients as low, intermediate, and high risk for event-free survival provides information on absolute individual risks, which may support decisions for pharmacological and interventional management.

A Rare Case of Coronary Artery Embolism in a Patient with d-Transposition of the Great Arteries with Prior Mustard Repair.

The dextro-transposition of great arteries (d-TGA) is a rare, congenital, cyanotic heart disease and there is a paucity of data regarding long-term cardiovascular outcomes. We present a rare case of non-ST-elevation myocardial infarction (NSTEMI) in a patient with surgically repaired d-TGA. A 43-year-old male who had previously undergone a Mustard atrial switch palliative procedure presented with chest pain and diaphoresis and was diagnosed with NSTEMI. A coronary angiogram revealed a small, underdeveloped, left anterior descending and a large, left circumflex coronary artery with an acute embolic lesion. The embolic lesion was secondary to atrial fibrillation and was successfully treated with aspiration thrombectomy. This case highlights the variations in coronary anatomy in surgically repaired d-TGA and the importance of recognizing the potential for long-term complications in these cases.

High prevalence of baffle leaks in adults after atrial switch operations for transposition of the great arteries.

AIMS: To determine the prevalence of baffle leaks in adults after atrial switch operations for transposition of the great arteries, as these may predispose to paradoxical embolic events, particularly in patients with transvenous pacemaker or defibrillator leads. METHODS AND RESULTS: We routinely perform contrast echocardiography with agitated saline in all patients after atrial switch operations. For this study, we analysed patients who had saline contrast echocardiography between 2010 and 2012. The presence of baffle leaks and the severity of right-to-left shunting were assessed. We compared baseline characteristics and oxygen saturation at rest and during exercise between patients with and without baffle leaks. A total of 65 patients (56 Senning and 9 Mustard repair) without previously known baffle leaks were included (mean age 32 ± 8 years, 77% males). Right-to-left shunting was identified in 42 patients (65%) and occurred without provocation manoeuvres in 88%. There were no differences in baseline characteristics, echocardiographic findings, or exercise capacity between patients with and without baffle leaks, except for lower oxygen saturation at peak exercise in those with baffle leaks (29% had oxygen saturations below 90% at peak exercise compared to none without baffle leaks, P = 0.011). Four patients with baffle leaks had previous implantation of transvenous pacemaker leads; one of them had suffered a stroke. Two other patients with baffle leaks had a history of potential embolic stroke. CONCLUSIONS: Because of the high prevalence of baffle leaks in adults after atrial switch operations, we propose routine screening with agitated saline contrast, particularly prior to implantation of transvenous pacemaker or defibrillator leads.

Nonfluoroscopic Imaging as Guidance for Radiofrequency Ablation of Atrioventricular Nodal Reentrant Tachycardia after Mustard Repair.

Most tachycardias in the pulmonary venous atrium are inaccessible by direct means and require either a retrograde approach or a transseptal approach for ablation. We present a case in which successful radiofrequency ablation of common atrioventricular nodal reentrant tachycardia was accomplished via a retrograde transaortic approach guided by nonfluoroscopic mapping with use of the NavX™ mapping system. The patient was a 49-year-old woman who at the age of 4 years had undergone Mustard repair for complete dextrotransposition of the great arteries. Three-dimensional reconstructions of the ascending aorta, right ventricle, systemic venous atrium, left ventricle, and superior vena cava-inferior vena cava baffle complex were created, and the left-sided His bundle was marked. After a failed attempt at ablation from the systemic venous side, we eliminated the atrioventricular nodal reentrant tachycardia by ablation from the pulmonary venous side. This case is, to our knowledge, the first report of successful radiofrequency ablation of common atrioventricular nodal reentrant tachycardia after Mustard repair for this congenital cardiac malformation in which ablation was guided by 3-dimensional nonfluoroscopic imaging. This imaging technique enabled accurate anatomic location of the ablation catheters in relation to the His bundle marked from the systemic venous side.

Can we predict sudden cardiac death in long-term survivors of atrial switch surgery for transposition of the great arteries?

OBJECTIVE: This study aims to identify predictors of sudden cardiac death (SCD) in patients with transposition of the great arteries (TGA) who have undergone atrial baffle surgery with the Mustard or Senning operation. BACKGROUND: Patients with TGA and previous atrial baffle surgery are known to be at increased risk of SCD. Despite this, indications for insertion of an implantable cardiac defibrillator for primary prevention have not been established. METHODS: Eighty-nine patients with a diagnosis of TGA and previous Mustard or Senning repair were identified. Medical records were reviewed for SCD, aborted SCD, implantation of cardiac defibrillator (ICD), and use of cardiac medications. Clinically significant events (heart failure admissions, documented arrhythmias, and insertion of a pacemaker) were ascertained, and results of echocardiograms were explored. RESULTS: There were five SCDs in our population, and five patients underwent a primary prevention ICD insertion, with no subsequent sustained ventricular arrhythmia or aborted SCD. Patients who suffered SCD had undergone surgery at an older age (median 53 months vs. 14 months) in a slightly earlier era (median year of operation 1971 vs. 1975). Atrial arrhythmias requiring treatment were documented in 100% of the SCD and in 29% of the no SCD patients. CONCLUSIONS: Criteria for insertion of primary prevention implantable cardiac defibrillators postatrial baffle surgery remain to be established. In the SCD subgroup, surgery at an older age, earlier era of surgical repair, and history of atrial arrhythmia appear to convey an increased risk of sudden death.