Conduction system pacing learning curve: Left bundle pacing compared to His bundle pacing.

Introduction: Conduction system pacing (CSP), consisting of His bundle pacing (HBP) or left bundle branch area pacing (LBBAP) is a rapidly developing field. These pacing techniques result in single lead left ventricular resynchronisation. Understanding of the associated learning curve of the two techniques is an important consideration for new implanters/implanting centres. Methods: We conducted a review of the first 30 cases of both HBP and LBBAP at The Royal Brompton Hospital. The procedural duration and fluoroscopy time were used as surrogates for the learning curve of each technique. Results: Patient characteristics were similar in HBP and LBBAP groups; LV ejection fraction (46% vs 54%, p = 0.08), pre-procedural QRS duration (119 ms vs 128 ms, p = 0.32).Mean procedural duration was shorter for LBBAP than for HBP (87 vs 107mins, p = 0.04) and the drop in procedural duration was more marked in LBBAP, plateauing and remaining low at 80mins after the initial 10 cases. Fluoroscopic screening time mirrored procedural duration (8 min vs 16 min, p < 0.01). Discussion/Conclusion: Our data suggest that the CSP learning curve was shorter for LBBAP than for HBP and appears to plateaux after the first 10 cases, however the HBP learning curve is longer with continued improvement over the first 30 cases. The shorter learning curve of LBBAP in conjunction with the superior electrical parameters and simplified programming mean the establishment of a CSP program is potentially easier with LBBAP compared to with HBP.

Left bundle branch area pacing in congenital heart disease.

AIMS: Left bundle branch area pacing (LBBAP) has been shown to be effective and safe. Limited data are available on LBBAP in the congenital heart disease (CHD) population. This study aims to describe the feasibility and safety of LBBAP in CHD patients compared with non-CHD patients. METHODS AND RESULTS: This is a single-centre, non-randomized observational study recruiting consecutive patients with bradycardia indication. Demographic data, ECGs, imaging, and procedural data including lead parameters were recorded. A total of 39 patients were included: CHD group (n = 13) and non-CHD group (n = 26). Congenital heart disease patients were younger (55 ± 14.5 years vs. 73.2 ± 13.1, P < 0.001). Acute success was achieved in all CHD patients and 96% (25/26) of non-CHD patients. No complications were encountered in either group. The procedural time for CHD patients was comparable (96.4 ± 54 vs. 82.1 ± 37.9 min, P = 0.356). Sheath reshaping was required in 7 of 13 CHD patients but only in 1 of 26 non-CHD patients, reflecting the complex and distorted anatomy of the patients in this group. Lead parameters were similar in both groups; R wave (11 ± 7 mV vs. 11.5 ± 7.5, P = 0.881) and pacing threshold (0.6 ± 0.3 V vs. 0.7 ± 0.3, P = 0.392). Baseline QRS duration was longer in the CHD group (150 ± 28.2 vs. 118.6 ± 26.6 ms, P = 0.002). Despite a numerically greater reduction in QRS and a similar left ventricular activation time (65.9 ± 6.2 vs. 67 ± 16.8 ms, P = 0.840), the QRS remained longer in the CHD group (135.5 ± 22.4 vs. 106.9 ± 24.7 ms, P = 0.005). CONCLUSION: Left bundle branch area pacing is feasible and safe in CHD patients as compared to that in non-CHD patients. Procedural and fluoroscopy times did not differ between both groups. Lead parameters were satisfactory and stable over a short-term follow-up.

A collective European experience with left atrial appendage suture ligation using the LARIAT+ device.

AIMS: We report the collective European experience of percutaneous left atrial appendage (LAA) suture ligation using the recent generation LARIAT+ suture delivery device. METHODS AND RESULTS: A total of 141 patients with non-valvular atrial fibrillation and contraindication to oral anticoagulation (OAC), thrombo-embolic events despite OAC or electrical LAA isolation were enrolled at seven European hospitals to undergo LAA ligation. Patients were followed up by clinical visits and transoesophageal echocardiography (TOE) following LAA closure. Left atrial appendage ligation was completed in 138/141 patients (97.8%). Three patients did not undergo attempted deployment of the LARIAT device due to pericardial adhesion after previous epicardial ventricular tachycardia ablation (n = 1), a pericardial access-related complication (n = 1), and multiple posterior LAA lobes (n = 1). Serious 30-day procedural adverse events occurred in 4/141 patients (2.8%). There were two device-related LAA perforations (1.4%) not resulting in any corrective intervention as the LAA was completely sealed with the LARIAT. Minor adverse events occurred in 19 patients (13.5%), including two pericardial effusions due to procedure-related pericarditis requiring pericardiocentesis. Transoesophageal echocardiography was performed after LAA ligation in 103/138 patients (74.6%) after a mean of 181 ± 72 days. Complete LAA closure was documented in 100 patients (97.1%). Two patients (1.8% of patients with follow-up) experienced a transient ischaemic attack at 4 and 7 months follow-up, although there was no leak observed with TOE. There were two deaths during long-term follow-up which were both not device related. CONCLUSION: Initial experience with the LARIAT+ device demonstrates feasibility of LAA exclusion. Further larger prospective studies with longer follow-up are warranted.

Central Iliac Arteriovenous Anastomosis for Uncontrolled Hypertension: One-Year Results From the ROX CONTROL HTN Trial.

Creation of a central iliac arteriovenous anastomosis using a novel nitinol coupler device results in an immediate, significant reduction of blood pressure (BP). We present efficacy and safety findings at 12 months post-coupler insertion. This open-label, multicenter, prospective, randomized trial enrolled patients with a baseline office systolic BP ≥140 mm Hg and average daytime ambulatory BP ≥135/85 mm Hg. Subjects were randomly allocated to coupler implantation and continuing previous pharmacotherapy or to maintain previous treatment alone. At 12 months, 39 patients who had coupler therapy were included in the intention-to-treat analysis. Office-based systolic BP reduced by 25.1±23.3 mm Hg (baseline, 174±18 mm Hg; P<0.0001) post-coupler placement, and office diastolic BP reduced by 20.8±13.3 mm Hg (baseline, 100±13 mm Hg; P<0.0001). Mean 24-hour ambulatory BP reduced by 12.6±17.4/15.3±9.7 mm Hg (P<0.0001 for both). In a prespecified subset of patients who failed to respond adequately to prior renal denervation, coupler therapy led to highly significant reduction in office systolic/diastolic BP (30.7/24.1 mm Hg) and significant reduction in 24-hour ambulatory systolic/diastolic BP (12.4/14.4 mm Hg) at 12 months (n=9). After coupler therapy, 14 patients (33%) developed ipsilateral venous stenosis; all were treated successfully with venous stenting. These findings confirm the importance of arterial mechanics in the pathophysiology of hypertension and support the clinical use of a central iliac arteriovenous anastomosis. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01642498.

Percutaneous left atrial appendage occlusion using different technologies in the United Kingdom: A multicenter registry.

OBJECTIVES: This study aimed at assessing the feasibility and long-term efficacy of left atrial appendage occlusion (LAAO) in a "real world" setting. BACKGROUND: Although LAAO has recently emerged as an alternative to oral anticoagulants in patients with atrial fibrillation for the prevention of thromboembolic stroke, "real world" data about the procedure with different devices are lacking. METHODS: Eight centers in the United Kingdom contributed to a retrospective registry for LAAO procedures undertaken between July 2009 and November 2014. RESULTS: A total of 371 patients (72.9 ± 8.3 years old, 88.9% males) were enrolled. The overall procedure success was 92.5%, with major events in 3.5% of cases. The device choice was Watchman in 63% of cases, Amplatzer Cardiac Plug in 34.7%, Lariat in 1.7%, and Coherex WaveCrest in 0.6%. A significant improvement in procedure success (from 89.2% to 95.7%; P = 0.018) and reduction of acute major complications (from 6.5% to 0.5%; P = 0.001) were observed between procedures in the first and the second half of the recruitment time. An annual 90.1% relative risk reduction (RRR) for ischemic stroke, an 87.2% thromboembolic events RRR, and a 92.9% major bleeding RRR were observed, if compared with the predicted annual risks based on CHADS2, CHA2DS2-Vasc, and HAS-BLED scores, respectively, over a follow-up period of 24.7 ± 16.07 months. CONCLUSIONS: LAAO can be performed safely in a real world setting with good implant success rates and procedural outcomes. The long-term benefits of the procedure are reassuring in terms of both ischemic events and avoidance of severe bleeding associated with anticoagulation in this patient group. © 2016 Wiley Periodicals, Inc.

Evaluation of a novel high-resolution mapping system for catheter ablation of ventricular arrhythmias.

BACKGROUND: The mapping of ventricular arrhythmias in humans using a minibasket 64-electrode catheter paired with a novel automatic mapping system (Rhythmia) has not been evaluated. OBJECTIVE: The purpose of this study was to evaluate the safety and efficacy of mapping ventricular arrhythmias and clinical outcomes after ablation using this system. METHODS: Electroanatomic maps for ventricular arrhythmias were obtained during 20 consecutive procedures in 19 patients (12 with ventricular tachycardia [VT] and 2 with ventricular ectopy [VE]). High-density maps were acquired using automatic beat acceptance and automatic system annotation of electrograms. RESULTS: Forty-seven electroanatomic maps (including 3 right ventricular and 9 epicardial maps) were obtained. Left ventricular endocardial mapping by transseptal (n = 13) and/or transaortic (n = 11) access was safe with no complications related to the minibasket catheter. VT substrate maps (n = 14; median 10,184 points) consistently demonstrated late potentials with high resolution. VT activation maps (n = 25; median 6401 points) obtained by automatic annotation included 7 complete maps (covering ≥90% of the tachycardia cycle length) in 5 patients in whom the entire VT circuit was accurately visualized. VE timing maps (n = 8) successfully localized the origin of VEs in all, with all accepted beats consistent with clinical VEs. Over a median follow-up of 10 months, no arrhythmia recurrence was noted in 75% after VT ablation and 86% after VE ablation. CONCLUSION: In this first human experience for ventricular arrhythmias using this system, ultra-high-density maps were created rapidly and safely, with a reliable automatic annotation of VT and consistent recording of abnormal electrograms. Medium-term outcomes after ablation were encouraging. Further larger studies are needed to validate these findings.

Effect of Arteriovenous Anastomosis on Blood Pressure Reduction in Patients With Isolated Systolic Hypertension Compared With Combined Hypertension.

BACKGROUND: Options for interventional therapy to lower blood pressure (BP) in patients with treatment-resistant hypertension include renal denervation and the creation of an arteriovenous anastomosis using the ROX coupler. It has been shown that BP response after renal denervation is greater in patients with combined hypertension (CH) than in patients with isolated systolic hypertension (ISH). We analyzed the effect of ROX coupler implantation in patients with CH as compared with ISH. METHODS AND RESULTS: The randomized, controlled, prospective ROX Control Hypertension Study included patients with true treatment-resistant hypertension (office systolic BP ≥140 mm Hg, average daytime ambulatory BP ≥135/85 mm Hg, and treatment with ≥3 antihypertensive drugs including a diuretic). In a post hoc analysis, we stratified patients with CH (n=31) and ISH (n=11). Baseline office systolic BP (177±18 mm Hg versus 169±17 mm Hg, P=0.163) and 24-hour ambulatory systolic BP (159±16 mm Hg versus 154±11 mm Hg, P=0.463) did not differ between patients with CH and those with ISH. ROX coupler implementation resulted in a significant reduction in office systolic BP (CH: -29±21 mm Hg versus ISH: -22±31 mm Hg, P=0.445) and 24-hour ambulatory systolic BP (CH: -14±20 mm Hg versus ISH: -13±15 mm Hg, P=0.672), without significant differences between the two groups. The responder rate (office systolic BP reduction ≥10 mm Hg) after 6 months was not different (CH: 81% versus ISH: 82%, P=0.932). CONCLUSIONS: Our data suggest that creation of an arteriovenous anastomosis using the ROX coupler system leads to a similar reduction of office and 24-hour ambulatory systolic BP in patients with combined and isolated systolic hypertension. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01642498.

Left Atrial Appendage Electrical Isolation and Concomitant Device Occlusion to Treat Persistent Atrial Fibrillation: A First-in-Human Safety, Feasibility, and Efficacy Study.

BACKGROUND: Left atrial appendage (LAA) electric isolation is reported to improve persistent atrial fibrillation (AF) ablation outcomes. However, loss of LAA mechanical function may increase thromboembolic risk. Concomitant LAA electric isolation and occlusion as part of conventional AF ablation has never been tested in humans. We therefore evaluated the feasibility, safety, and efficacy of LAA electric isolation and occlusion in patients undergoing long-standing persistent AF ablation. METHODS AND RESULTS: Patients with long-standing persistent AF (age, 68±7 years; left atrium diameter, 46±3 mm; and AF duration, 25±15 months) underwent AF ablation, LAA electric isolation, and occlusion. Outcomes were compared with a balanced (1:2 ratio) control group who had AF ablation alone. Among 22 patients who underwent ablation, LAA electric isolation was possible in 20. Intraprocedural LAA reconnection occurred in 17 of 20 (85%) patients, predominantly at anterior and superior locations. All were reisolated. LAA occlusion was successful in all 20 patients. There were no major periprocedural complications. Imaging at 45 days and 9 months confirmed satisfactory device position and excluded pericardial effusion. One of twenty (5%) patients had a gap of ≥5 mm requiring anticoagulation. Nineteen of twenty (95%) patients stopped warfarin at 3 months. Without antiarrhythmic drugs, freedom from AF at 12 months after a single procedure was significantly higher in the study group (19/20, 95%) than in the control group (25/40, 63%), P=0.036. Freedom from atrial arrhythmias was demonstrated in 12 of 20 (60%) and 18 of 20 (90%) patients after 1 and ≤2 procedures (mean, 1.3), respectively. CONCLUSIONS: Persistent AF ablation, LAA electric isolation, and mechanical occlusion can be performed concomitantly. This technique may improve the success of persistent AF ablation while obviating the need for chronic anticoagulation. CLINICAL TRIAL REGISTRATION: URL: https://clinicaltrials.gov. Unique identifier: NCT02028130.

Left atrial appendage ligation with the next generation LARIAT(+) suture delivery device: Early clinical experience.

BACKGROUND: The purpose of the study was to determine the efficacy and safety of left atrial appendage (LAA) closure with a micropuncture pericardial access approach and the new LARIAT(+) suture delivery device. METHODS: Seventy-two patients with atrial fibrillation were enrolled to undergo telescopic micropuncture pericardial access and percutaneous ligation of the LAA with the LARIAT(+) device. LAA closure was confirmed with transesophageal echocardiography (TEE) and contrast fluoroscopy immediately, then with TEE at 30days and 90days post-LAA ligation. Patients were monitored for 12months by an independent clinical research organization for adverse events, stroke, embolic events and death of any cause. RESULTS: 72 patients were screened for the LARIAT(+) procedure. Fourteen patients were screened failures (7 patients due to unfavorable anatomy and 7 patients with LAA thrombus). Fifty-eight patients underwent successful LAA ligation. All 58 patients had complete acute closure of the LAA. At 1month 52 of 54 patients (96.3%) had LAA closure, while at 3months 48 of 52 patients (92.3%) had LAA closure. There were no leaks greater than 3mm at both 1 and 3months. There were no device or procedural related complications, and only 1 30day adverse event involving late pericardial effusion. There were no strokes, embolic events or deaths after 12months. CONCLUSIONS: LAA closure with the micropuncture pericardial access approach and the LARIAT(+) device can be performed effectively with acceptably low periprocedural adverse events.

Outcomes and costs of left atrial appendage closure from randomized controlled trial and real-world experience relative to oral anticoagulation.

AIMS: The aim of this study was to analyse randomized controlled study and real-world outcomes of patients with non-valvular atrial fibrillation (NVAF) undergoing left atrial appendage closure (LAAC) with the Watchman device and to compare costs with available antithrombotic therapies. METHODS AND RESULTS: Registry data of LAAC from two centres were prospectively collected from 110 patients with NVAF at risk of stroke, suitable and unsuitable for long-term anticoagulation (age 71.3 ± 9.2 years, CHADS2 2.8 ± 1.2, CHA2DS2-VASc 4.5 ± 1.6, and HAS-BLED 3.8 ± 1.1). Outcomes from PROTECT AF and registry study LAAC were compared with warfarin, dabigatran, rivaroxaban, apixaban, aspirin, and no treatment using a network meta-analysis. Costs were estimated over a 10-year horizon. Uncertainty was assessed using sensitivity analyses. The procedural success rate was 92% (103/112). Follow-up was 24.1 ± 4.6 months, during which annual rates of stroke, major bleeding, and all-cause mortality were 0.9% (2/223 patient-years), 0.9% (2/223 patient-years), and 1.8% (4/223 patient-years), respectively. Anticoagulant therapy was successfully stopped in 91.2% (93/102) of implanted patients by 12 months. Registry study LAAC stroke and major bleeding rates were significantly lower than PROTECT AF results: mean absolute difference of stroke, 0.89% (P = 0.02) and major bleeding, 5.48% (P < 0.001). Left atrial appendage closure achieved cost parity between 4.9 years vs. dabigatran 110 mg and 8.4 years vs. warfarin. At 10 years, LAAC was cost-saving against all therapies (range £1162-£7194). CONCLUSION: Left atrial appendage closure in NVAF in a real-world setting may result in lower stroke and major bleeding rates than reported in LAAC clinical trials. Left atrial appendage closure in both settings achieves cost parity in a relatively short period of time and may offer substantial savings compared with current therapies. Savings are most pronounced among higher risk patients and those unsuitable for anticoagulation.

CT imaging for left atrial appendage closure: a review and pictorial essay.

Cardioembolic stroke is an important complication of atrial fibrillation. The thrombus responsible for this arises from the left atrial appendage (LAA) in >90% of cases, providing the rationale for device-based LAA closure as a means of thromboprophylaxis. Although oral anticoagulant therapy remains the mainstay for reducing the risk of stroke in patients with atrial fibrillation, an increasing number of patients, particularly those ineligible for conventional pharmacotherapy, are being offered percutaneous left atrial appendage closure. Cardiovascular CT can provide important information to assess the suitability of patients for LAA interventions and guide device selection and approach. The high spatial resolution and multiplanar capability of contemporary contrast-enhanced gated multidetector cardiovascular CT render it an ideal modality for noninvasively evaluating patients before intervention and assessing patients after intervention both for complications and procedural outcome.

Central arteriovenous anastomosis for the treatment of patients with uncontrolled hypertension (the ROX CONTROL HTN study): a randomised controlled trial.

BACKGROUND: Hypertension contributes to cardiovascular morbidity and mortality. We assessed the safety and efficacy of a central iliac arteriovenous anastomosis to alter the mechanical arterial properties and reduce blood pressure in patients with uncontrolled hypertension. METHODS: We enrolled patients in this open-label, multicentre, prospective, randomised, controlled trial between October, 2012, and April, 2014. Eligible patients had baseline office systolic blood pressure of 140 mm Hg or higher and average daytime ambulatory blood pressure of 135 mm Hg or higher systolic and 85 mm Hg or higher diastolic despite antihypertensive treatment. Patients were randomly allocated in a 1:1 ratio to undergo implantation of an arteriovenous coupler device plus current pharmaceutical treatment or to maintain current treatment alone (control). The primary endpoint was mean change from baseline in office and 24 h ambulatory systolic blood pressure at 6 months. Analysis was by modified intention to treat (all patients remaining in follow-up at 6 months). This trial is registered with ClinicalTrials.gov, number NCT01642498. FINDINGS: 83 (43%) of 195 patients screened were assigned arteriovenous coupler therapy (n=44) or normal care (n=39). Mean office systolic blood pressure reduced by 26·9 (SD 23·9) mm Hg in the arteriovenous coupler group (p<0·0001) and by 3·7 (21·2) mm Hg in the control group (p=0·31). Mean systolic 24 h ambulatory blood pressure reduced by 13·5 (18·8) mm Hg (p<0·0001) in arteriovenous coupler recipients and by 0·5 (15·8) mm Hg (p=0·86) in controls. Implantation of the arteriovenous coupler was associated with late ipsilateral venous stenosis in 12 (29%) of 42 patients and was treatable with venoplasty or stenting. INTERPRETATION: Arteriovenous anastomosis was associated with significantly reduced blood pressure and hypertensive complications. This approach might be a useful adjunctive therapy for patients with uncontrolled hypertension. FUNDING: ROX Medical.

The ROX coupler: creation of a fixed iliac arteriovenous anastomosis for the treatment of uncontrolled systemic arterial hypertension, exploiting the physical properties of the arterial vasculature.

OBJECTIVES: Uncontrolled hypertension, whether due to drug resistance or poor adherence and persistence, remains a problem in many patients. The ROX coupler is a novel technology designed to reduce arterial blood pressure consequent to the predicted physical effects of reducing vascular resistance and improving arterial compliance. This article describes the technical aspects of the device and implantation procedure, results from a preclinical study, patient selection criteria, and potential complications of this therapy for uncontrolled hypertension. BACKGROUND: The coupler is a self-expanding, stent-like device that exploits the mechanical effects of the creation of a low-resistance, high-compliance venous segment to the central arterial tree, and can be implanted in a standard catheterization laboratory under fluoroscopic guidance. METHODS: Preclinical studies were conducted in sheep with acute or chronic hypertension. The devices were implanted in the aorta for up to 12 months. The anastomoses were evaluated for patency, healing, conformation into the artery and vein, and complications. RESULTS: Deployment of the anastomotic device in ovine aortas for up to 12 months showed optimal anastomotic patency in all animals with proper healing and conformation of the device into the artery and the vein. There was no significant residual mural thrombus and minimal to moderate intimal thickening at the vein outflow, consistent with expected arterialization. CONCLUSIONS: A novel arteriovenous coupler for percutaneous placement in the iliac vasculature is under clinical investigation as a potential treatment modality for selected patients with uncontrolled hypertension. Initial results from patients with uncontrolled hypertension are expected in Autumn 2014.

Use of asymmetric bidirectional catheters with different curvature radius for catheter ablation of cardiac arrhythmias.

BACKGROUND: The impact of recently introduced asymmetric bidirectional ablation catheters on procedural parameters and acute success rates of ablation procedures is unknown. METHODS: We retrospectively analyzed data regarding ablations using a novel bidirectional catheter in a tertiary cardiac center and compared these in 1:5 ratio with a control group of procedures matched for age, gender, operator, and ablation type. RESULTS: A total of 50 cases and 250 controls of median age 60 (50-68) years were studied. Structural heart disease was equally prevalent in both groups (39%) while history of previous ablations was more common in the study arm (54% vs 30%, P = 0.001). Most of the ablation cases were for atrial fibrillation (46%), followed by atrial tachycardia (28%), supraventricular tachycardia (12%), and ventricular tachycardia (14%). Median procedure duration was 128 (52-147) minutes with the bidirectional, versus 143 (105-200) minutes with the conventional catheter (P = 0.232), and median fluoroscopy time was 17 (10-34) minutes versus 23 (12-39) minutes, respectively (P = 0.988). There was a trend toward a lower procedure duration for the atrial tachycardia ablations, 89 (52-147) minutes versus 130 (100-210) minutes, P = 0.064. The procedure was successfully completed in 96% of the bidirectional versus 84% of the control cases (P = 0.151). A negative correlation was observed between the relative fluoroscopy duration and the case number (r = -0.312, P = 0.028), reflecting the learning curve for the bidirectional catheter. CONCLUSIONS: The introduction of the bidirectional catheter resulted in no prolongation of procedure parameters and similar success rates, while there was a trend toward a lower procedure duration for atrial tachycardia ablations.

Extending the boundaries of the primary arterial switch operation in patients with transposition of the great arteries and intact ventricular septum.

BACKGROUND: We have previously suggested that the primary arterial switch operation is a feasible strategy for patients with transposition of the great arteries and intact ventricular septum (TGA-IVS) up to age 2 months. This study reports our current results with this approach and examines whether this policy could be extended beyond age 2 months. METHODS AND RESULTS: 380 patients who underwent arterial switch for TGA-IVS were reviewed. 275 patients were younger than 3 weeks at the time of surgery (early switch group); 105 patients were 3 weeks or older (range, 21 to 185 days) (late switch group). There was no difference in outcome in terms of in-hospital mortality (5.5% versus 3.8%) or need for mechanical circulatory support (3.6% versus 5.7%) between early and late switch groups. However, duration of postoperative ventilation (4.9 versus 7.1 days, P=0.012) and length of postoperative stay (12.5 versus 18.9 days, P<0.001) were significantly prolonged in the late switch group. Primary left ventricular failure resulting in death occurred in 2 patients in the late switch group, with no deaths in 9 patients aged 2 to 6 months. CONCLUSIONS: This experience confirms that in TGA-IVS, the left ventricle maintains the potential for systemic work well beyond the first month of life. Consequently, neonates at high risk or late referrals can benefit from delayed arterial switch, even beyond age 2 months. However, the need for mechanical support in some of the older patients may limit the widespread adoption of such a strategy.