Percutaneous Balloon-Expandable Stent Implantation to Treat Transverse Aortic Arch Obstruction: Medium- to Long-Term Outcomes of a Retrospective Multicenter Study.

BACKGROUND: Transverse aortic arch obstruction is a challenging lesion for which stent implantation provides a potentially important alternate therapy. The objectives were to evaluate the technical, procedural, and medium-to-long-term clinical outcomes of percutaneous stent implantation of transverse aortic arch obstruction. METHODS: This is a retrospective, multicenter study of transverse aortic arch stent implantation. Univariable and multivariable analyses were performed. RESULTS: Index catheterization included 187 stent implants in 146 patients. The median age is 14.3 years (interquartile range, 9.3-19), weight is 53 kg (30-69), and follow-up is 53 months (12-120). The most common stent design was open cell (n=90, 48%). Stents overlapped 142 arch vessels (37 carotid arteries) in 118 (81%) cases. Technical and procedural success rates were 100% and 88%, respectively. Lower weight (P=0.018), body surface area (P=0.013), and minimum-to-descending aortic diameter ratio (P<0.001) were associated with higher baseline aortic gradient. The residual gradient was inversely associated with implant and final dilation diameters (P<0.001). The combined incidence of aortic injury and stent-related complications was 14%. There were no reports of abnormal brain scans or stroke. Blood pressure cuff gradient, echocardiographic arch velocity, and hypertension rates improved within 1-year follow-up with increased antihypertensive medication use. Reintervention was reported in 60 (41%) patients at a median of 84 (22-148) months to first reintervention. On multivariable logistic regression, residual aortic gradient >10 mm Hg was associated with increased odds of reintervention at all time points when controlling for each final dilation diameter, weight, and minimum-to-descending aortic diameter ratio. CONCLUSIONS: Transverse aortic arch stent implantation has high rates of technical, procedural, and medium-to-long-term clinical success. Aortic gradient >10 mm Hg is associated with increased odds of reintervention at 1-year and most recent follow-ups. Open cell stent design was frequently used for its advantages in conformability, perfusion of arch vessels, low fracture rate, and the ability to perform effective angioplasty of side cells.

1-Year Outcomes in a Pooled Cohort of Harmony Transcatheter Pulmonary Valve Clinical Trial Participants.

BACKGROUND: The Harmony transcatheter pulmonary valve (TPV) is the first U.S. Food and Drug Administration-approved device for severe pulmonary regurgitation (PR) in the native or surgically repaired right ventricular outflow tract (RVOT). OBJECTIVES: One-year safety and effectiveness of the Harmony TPV were evaluated in patients from the Harmony Native Outflow Tract Early Feasibility Study, Harmony TPV Pivotal Study, and Continued Access Study, representing the largest cohort to date of Harmony TPV recipients. METHODS: Eligible patients had severe PR by echocardiography or PR fraction ≥ 30% by cardiac magnetic resonance imaging and clinical indications for pulmonary valve replacement. The primary analysis included 87 patients who received a commercially available TPV22 (n = 42) or TPV25 (n = 45) device; 19 patients who received an early device iteration prior to its discontinuation were evaluated separately. RESULTS: In the primary analysis, median patient age at treatment was 26 years (IQR: 18-37 years) in the TPV22 group and 29 years (IQR: 19-42 years) in the TPV25 group. At 1 year, there were no deaths; 98% of TPV22 and 91% of TPV25 patients were free from the composite of PR, stenosis, and reintervention (moderate or worse PR, mean RVOT gradient >40 mmHg, device-related RVOT reoperation, and catheter reintervention). Nonsustained ventricular tachycardia occurred in 16% of patients. Most patients had none/trace or mild PR (98% of TPV22 patients, 97% of TPV25 patients). Outcomes with the discontinued device are reported separately. CONCLUSIONS: The Harmony TPV device demonstrated favorable clinical and hemodynamic outcomes across studies and valve types through 1 year. Further follow-up will continue to assess long-term valve performance and durability.

A first-in-human phase I/IIa gene transfer clinical trial for Duchenne muscular dystrophy using rAAVrh74.MCK.GALGT2.

In a phase 1/2, open-label dose escalation trial, we delivered rAAVrh74.MCK.GALGT2 (also B4GALNT2) bilaterally to the legs of two boys with Duchenne muscular dystrophy using intravascular limb infusion. Subject 1 (age 8.9 years at dosing) received 2.5 × 1013 vector genome (vg)/kg per leg (5 × 1013 vg/kg total) and subject 2 (age 6.9 years at dosing) received 5 × 1013 vg/kg per leg (1 × 1014 vg/kg total). No serious adverse events were observed. Muscle biopsy evaluated 3 or 4 months post treatment versus baseline showed evidence of GALGT2 gene expression and GALGT2-induced muscle cell glycosylation. Functionally, subject 1 showed a decline in 6-min walk test (6MWT) distance; an increase in time to run 100 m, and a decline in North Star Ambulatory Assessment (NSAA) score until ambulation was lost at 24 months. Subject 2, treated at a younger age and at a higher dose, demonstrated an improvement over 24 months in NSAA score (from 20 to 23 points), an increase in 6MWT distance (from 405 to 478 m), and only a minimal increase in 100 m time (45.6-48.4 s). These data suggest preliminary safety at a dose of 1 × 1014 vg/kg and functional stabilization in one patient.

Reintervention and Survival After Transcatheter Pulmonary Valve Replacement.

BACKGROUND: Transcatheter pulmonary valve (TPV) replacement (TPVR) has become the standard therapy for postoperative pulmonary outflow tract dysfunction in patients with a prosthetic conduit/valve, but there is limited information about risk factors for death or reintervention after this procedure. OBJECTIVES: This study sought to evaluate mid- and long-term outcomes after TPVR in a large multicenter cohort. METHODS: International registry focused on time-related outcomes after TPVR. RESULTS: Investigators submitted data for 2,476 patients who underwent TPVR and were followed up for 8,475 patient-years. A total of 95 patients died after TPVR, most commonly from heart failure (n = 24). The cumulative incidence of death was 8.9% (95% CI: 6.9%-11.5%) 8 years after TPVR. On multivariable analysis, age at TPVR (HR: 1.04 per year; 95% CI: 1.03-1.06 per year; P < 0.001), a prosthetic valve in other positions (HR: 2.1; 95% CI: 1.2-3.7; P = 0.014), and an existing transvenous pacemaker/implantable cardioverter-defibrillator (HR: 2.1; 95% CI: 1.3-3.4; P = 0.004) were associated with death. A total of 258 patients underwent TPV reintervention. At 8 years, the cumulative incidence of any TPV reintervention was 25.1% (95% CI: 21.8%-28.5%) and of surgical TPV reintervention was 14.4% (95% CI: 11.9%-17.2%). Risk factors for surgical reintervention included age (0.95 per year [95% CI: 0.93-0.97 per year]; P < 0.001), prior endocarditis (2.5 [95% CI: 1.4-4.3]; P = 0.001), TPVR into a stented bioprosthetic valve (1.7 [95% CI: 1.2-2.5]; P = 0.007), and postimplant gradient (1.4 per 10 mm Hg [95% CI: 1.2-1.7 per 10 mm Hg]: P < 0.001). CONCLUSIONS: These findings support the conclusion that survival and freedom from reintervention or surgery after TPVR are generally comparable to outcomes of surgical conduit/valve replacement across a wide age range.

Pre-clinical Evolution of a Novel Transcatheter Bioabsorbable ASD/PFO Occluder Device.

To date, there has been limited investigation of bioabsorbable atrial septal defect (ASD) or patent foramen ovale (PFO) closure devices using clinically relevant large animal models. The purpose of this study is to explore the function and safety of a bioabsorbable ASD occluder (BAO) system for PFO and/or secundum ASD transcatheter closure. Using a sheep model, the intra-atrial septum was evaluated by intracardiac echo (ICE). If a PFO was not present, atrial communication was created via transseptal puncture. Device implantation across the intra-atrial communication was performed with fluoroscopic and ICE guidance. Our 1st generation device consisted of a main structure of thin Poly(L-lactide-co-epsilon-caprolactone) (PLCL) fibers, and an internal Poly glycolic acid (PGA) fabric. Four procedures validated procedure feasibility. Subsequently, device design was modified for improved transcatheter delivery. The 2nd generation device has a two-layered structure and was implanted in six sheep. Results showed procedural success in 9/10 (90%) animals. With deployment, the 1st generation device did not reform into its original disk shape and did not conform nicely along the atrial septum. The 2nd generation device was implanted in six animals, 3 out of 6 survived out to 1 year. At 1 year post implantation, ICE confirmed no residual shunting. By necropsy, biomaterials had partially degraded, and histology of explanted samples revealed significant device endothelialization and biomaterial replacement with a collagen layer. Our results demonstrate that our modified 2nd generation BAO can be deployed via minimally invasive percutaneous transcatheter techniques. The BAO partially degrades over 1 year and is replaced by host native tissues. Future studies are needed prior to clinical trials.

Long-Term Outcomes After Melody Transcatheter Pulmonary Valve Replacement in the US Investigational Device Exemption Trial.

BACKGROUND: The Melody valve was developed to extend the useful life of previously implanted right ventricular outflow tract (RVOT) conduits or bioprosthetic pulmonary valves, while preserving RV function and reducing the lifetime burden of surgery for patients with complex congenital heart disease. METHODS: Enrollment for the US Investigational Device Exemption study of the Melody valve began in 2007. Extended follow-up was completed in 2020. The primary outcome was freedom from transcatheter pulmonary valve (TPV) dysfunction (freedom from reoperation, reintervention, moderate or severe pulmonary regurgitation, and/or mean RVOT gradient >40 mm Hg). Secondary end points included stent fracture, catheter reintervention, surgical conduit replacement, and death. RESULTS: One hundred seventy-one subjects with RVOT conduit or bioprosthetic pulmonary valve dysfunction were enrolled. One hundred fifty underwent Melody TPV replacement. Median age was 19 years (Q1-Q3: 15-26). Median discharge mean RVOT Doppler gradient was 17 mm Hg (Q1-Q3: 12-22). The 149 patients implanted >24 hours were followed for a median of 8.4 years (Q1-Q3: 5.4-10.1). At 10 years, estimated freedom from mortality was 90%, from reoperation 79%, and from any reintervention 60%. Ten-year freedom from TPV dysfunction was 53% and was significantly shorter in children than in adults. Estimated freedom from TPV-related endocarditis was 81% at 10 years (95% CI, 69%-89%), with an annualized rate of 2.0% per patient-year. CONCLUSIONS: Ten-year outcomes from the Melody Investigational Device Exemption trial affirm the benefits of Melody TPV replacement in the lifetime management of patients with RVOT conduits and bioprosthetic pulmonary valves by providing sustained symptomatic and hemodynamic improvement in the majority of patients. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT00740870.

Transcatheter Pulmonary Valve Replacement: A Review of Current Valve Technologies.

Transcatheter pulmonary valve replacement was first performed by Dr Philip Bonhoeffer, who implanted a Medtronic Melody valve in a human in 2000. Over the past 2 decades, there have been many advances in transcatheter pulmonary valve technology. This includes the use of the SAPIEN transcatheter heart valve in the pulmonary position, modifications and refinements to valve implantation procedures, and development of self-expanding valves and prestents to treat large diameter native or patched right ventricular outflow tracts. This article reviews the current transcatheter pulmonary valve technologies with a focus on valve design, screening process, implant procedure, and clinical outcomes.

Multicenter Study of Endocarditis After Transcatheter Pulmonary Valve Replacement.

BACKGROUND: Endocarditis has emerged as one of the most impactful adverse events after transcatheter pulmonary valve replacement (TPVR), but there is limited information about risk factors for and outcomes of this complication. OBJECTIVES: The purpose of this study was to evaluate risk factors for and outcomes of endocarditis in a large multicenter cohort. METHODS: The authors established an international registry focused on characterizing endocarditis after TPVR, including the incidence, risk factors, characteristics, and outcomes. RESULTS: Investigators submitted data for 2,476 patients who underwent TPVR between July 2005 and March 2020 and were followed for 8,475 patient-years. In total, 182 patients were diagnosed with endocarditis a median of 2.7 years after TPVR, for a cumulative incidence of 9.5% (95% CI: 7.9%-11.1%) at 5 years and 16.9% (95% CI: 14.2%-19.8%) at 8 years (accounting for competing risks: death, heart transplant, and explant) and an annualized incidence of 2.2 per 100 patient-years. Staphylococcus aureus and Viridans group Streptococcus species together accounted for 56% of cases. Multivariable analysis confirmed that younger age, a previous history of endocarditis, and a higher residual gradient were risk factors for endocarditis, but transcatheter pulmonary valve type was not. Overall, right ventricular outflow tract (RVOT) reintervention was less often to treat endocarditis than for other reasons, but valve explant was more often caused by endocarditis. Endocarditis was severe in 44% of patients, and 12 patients (6.6%) died, nearly all of whom were infected with Staphylococcus aureus. CONCLUSIONS: The incidence of endocarditis in this multicenter registry was constant over time and consistent with prior smaller studies. The findings of this study, along with ongoing efforts to understand and mitigate risk, will be critical to improve the lifetime management of patients with heart disease involving the RVOT. Although endocarditis can be a serious adverse outcome, TPVR remains an important tool in the management of RVOT dysfunction.

Comparison of the investigational device exemption and post-approval trials of the Melody transcatheter pulmonary valve.

OBJECTIVE: We compared 5-year outcomes of transcatheter pulmonary valve (TPV) replacement with the Melody TPV in the post-approval study (PAS) and the investigational device exemption (IDE) trial. BACKGROUND: As a condition of approval of the Melody TPV after the IDE trial, the Food and Drug Administration required that a PAS be conducted to evaluate outcomes of TPV replacement in a "real-world" environment. The 5-year outcomes of the PAS have not been published, and the IDE and PAS trials have not been compared. METHODS: The cohorts comprised all patients catheterized and implanted at 5 IDE sites and 10 PAS sites. Differences in trial protocols were detailed. Time-related outcomes and valve-related adverse events were compared between the two trials with Kaplan-Meier curves and log-rank testing. RESULTS: 167 patients (median age, 19 years) were catheterized and 150 underwent TPV replacement in the IDE trial; 121 were catheterized (median age, 17 years) and 100 implanted in the PAS. Freedom from hemodynamic dysfunction (p = .61) or any reintervention (p = .74) over time did not differ between trials. Freedom from stent fracture (p = .003) and transcatheter reintervention (p = .010) were longer in PAS, whereas freedom from explant (p = .020) and TPV endocarditis (p = .007) were shorter. Clinically important adverse events (AEs) were reported in 14% of PAS and 7.2% of IDE patients (p = .056); the incidence of any particular event was low in both. CONCLUSIONS: Hemodynamic and time-related outcomes in the PAS and IDE trials were generally similar, confirming the effectiveness of the Melody TPV with real-world providers. There were few significant complications and limited power to identify important differences in AEs. The lack of major differences in outcomes between the two studies questions the usefulness of mandated costly post-approval studies as part of the regulatory process for Class III medical devices.

Percutaneous Implantation of Adult Sized Stents for Coarctation of the Aorta in Children ≤20 kg: A 12-Year Experience.

BACKGROUND: Stent implantation (SI) is more effective than balloon angioplasty for the treatment of coarctation of the aorta (CoA). Due to technical factors, balloon angioplasty is more commonly performed in small patients. We sought to evaluate outcomes of percutaneous adult sized SI for the treatment of CoA in small patients. METHODS: A single-center retrospective review of all patients ≤20 kg who underwent percutaneous adult sized SI for native or recurrent CoA from 2004 to 2015 was performed. RESULTS: Thirty-nine patients (20 patients ≤10 kg) were identified, with 28 (71.8%) having recurrent CoA and 22 (56.4%) previously failed balloon angioplasty. At the time of SI, the median (range) patient age and weight were 1.1 (0.3-7.9) years and 10 (5.5-20.4) kg, respectively. SI resulted in significant improvements in the median gradient (26 mm Hg [interquartile range (IQR), 18-42] to 0 mm Hg [IQR, 0-2]; P< 0.05) and median minimum diameter (3.6 mm [IQR, 2.4-4.8] to 7.7 mm [IQR, 6.5-9.4]; P<0.05). Seven patients (18%) had procedural adverse events. Twenty-seven (69%) patients underwent elective reintervention at a median time of 49.3 (IQR, 26.5-63.2) months from SI, with 8 (21%) stents requiring repeat SI for stent fracture. Over a median follow-up of 67.2 (IQR, 33.8-116.1) months, 25 patients (69%) were without hypertension or blood pressure gradient. Three (11%) patients developed femoral arterial occlusion. CONCLUSIONS: Adult sized SI is an alternative to surgical intervention for small patients with CoA. SI carries a risk of access-related complications, which may improve with the development of lower profile stents with adult sized maximum diameters.

Outcomes After Transcatheter Reintervention for Dysfunction of a Previously Implanted Transcatheter Pulmonary Valve.

OBJECTIVES: The aim of this analysis was to evaluate outcomes following transcatheter reintervention for degenerated transcatheter pulmonary valves (TPVs). BACKGROUND: TPV replacement (TPVR) with the Melody valve demonstrated sustained relief of right ventricular outflow tract (RVOT) obstruction and pulmonary regurgitation. METHODS: All patients who underwent TPVR with a Melody valve as part of 3 Medtronic-sponsored prospective multicenter studies were included. Transcatheter reinterventions included balloon dilation of the previously implanted Melody valve, placement of a bare-metal stent within the implanted TPV, or placement of a new TPV in the RVOT (TPV-in-TPV). Indications for reintervention, decisions to reintervene, and the method of reintervention were at physician discretion. All patients provided written informed consent to participate in the trials, and each trial was approved by local or central Institutional Review Boards or ethics committees at participating sites. RESULTS: A total of 309 patients who underwent TPVR were discharged from the implantation hospitalization with Melody valves in place. Transcatheter reintervention on the TPV was performed in 46 patients. The first transcatheter reintervention consisted of TPV-in-TPV in 28 patients (median 6.9 years [quartile 1 to quartile 3: 5.2 to 7.8 years] after TPVR), simple balloon dilation of the implanted Melody valve in 17 (median 4.9 years [quartile 1 to quartile 3: 4.0 to 6.0 years] after TPVR), and bare-metal stent placement alone in 1 (4.4 years after TPVR). There were no major procedural complications. Overall, 4-year freedom from explant and from any later RVOT reintervention after the first reintervention were 83% and 60%, respectively. Freedom from repeat RVOT reintervention was longer in patients undergoing TPV-in-TPV than balloon dilation (71% vs. 46% at 4 years; p = 0.027). CONCLUSIONS: TPV-in-TPV can be an effective and durable treatment for Melody valve dysfunction. Although balloon dilation of the Melody valve was also acutely effective at reducing RVOT obstruction, the durability of this therapy was limited in this cohort compared with TPV-in-TPV.

Three-Year Outcomes From the Harmony Native Outflow Tract Early Feasibility Study.

BACKGROUND: The Harmony transcatheter pulmonary valve (TPV) was designed for treatment of postoperative pulmonary valve regurgitation in patients with repaired right ventricular outflow tracts. METHODS: The Native TPV EFS (Early Feasibility Study) is a prospective, multicenter, nonrandomized feasibility study. Three-year outcomes are reported. RESULTS: Of 20 implanted patients, 17 completed 3-year follow-up (maximum: 4.1 years). There were no deaths and 2 early explants. One patient did not complete the 3-year visit. In patients with available 3-year echocardiographic data, 1 had a mild paravalvular leak and the rest had none/trace; 1 patient had mild pulmonary valve regurgitation and the remainder had none/trace. The 3-year mean right ventricular outflow tract echocardiographic gradient was 15.7±5.5 mm Hg. Radiographically, no late frame fractures or erosions were identified. At 2 years, 2 patients presented with an increased echocardiographic outflow gradient (1 mixed lesion with moderate/severe pulmonary valve regurgitation). Computed tomography scans identified neointimal tissue ingrowth within the stent frame in both patients, and they were treated successfully with a transcatheter valve-in-valve procedure (Melody TPV). Additional follow-up computed tomography scans performed at 3.2±0.5 years after implant were obtained in 16 patients and revealed luminal tissue thickening at the inflow and outflow portion of the frame with no significant alteration of the valve housing. CONCLUSIONS: Three-year results from the Native TPV EFS revealed stable Harmony TPV device position, good valve function in most, and the absence of moderate/severe paravalvular leak and significant late frame fractures. Two patients developed significant neointimal proliferation requiring valve-in-valve treatment, while all others had no clinically significant right ventricular outflow tract obstruction. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01762124.

Spontaneous reversal of stenosis in tissue-engineered vascular grafts.

We developed a tissue-engineered vascular graft (TEVG) for use in children and present results of a U.S. Food and Drug Administration (FDA)-approved clinical trial evaluating this graft in patients with single-ventricle cardiac anomalies. The TEVG was used as a Fontan conduit to connect the inferior vena cava and pulmonary artery, but a high incidence of graft narrowing manifested within the first 6 months, which was treated successfully with angioplasty. To elucidate mechanisms underlying this early stenosis, we used a data-informed, computational model to perform in silico parametric studies of TEVG development. The simulations predicted early stenosis as observed in our clinical trial but suggested further that such narrowing could reverse spontaneously through an inflammation-driven, mechano-mediated mechanism. We tested this unexpected, model-generated hypothesis by implanting TEVGs in an ovine inferior vena cava interposition graft model, which confirmed the prediction that TEVG stenosis resolved spontaneously and was typically well tolerated. These findings have important implications for our translational research because they suggest that angioplasty may be safely avoided in patients with asymptomatic early stenosis, although there will remain a need for appropriate medical monitoring. The simulations further predicted that the degree of reversible narrowing can be mitigated by altering the scaffold design to attenuate early inflammation and increase mechano-sensing by the synthetic cells, thus suggesting a new paradigm for optimizing next-generation TEVGs. We submit that there is considerable translational advantage to combined computational-experimental studies when designing cutting-edge technologies and their clinical management.

Utility of CT Angiography for the Prediction of Coronary Artery Compression in Patients Undergoing Transcatheter Pulmonary Valve Replacement.

OBJECTIVES: We aimed to evaluate the utility of computed tomography angiography (CTA) for coronary compression (CC) prediction in patients with congenital heart disease undergoing balloon-expandable transcatheter pulmonary valve replacement (TPVR). BACKGROUND: Coronary compression is a serious complication of TPVR, but the value of preprocedural CTAs to assess CC risk is largely unexplored. METHODS: In all, 586 patients underwent TPVR between January 2009 and July 2018. Adults with a pre-TPVR CTA and children with a CTA performed less than one year prior to TPVR were included. Patients with poor CTA image quality or with aborted cases due to reasons other than CC were excluded. Sixty-six patients were finally included. Cardiac anatomy was assessed via multiplanar reconstruction of CTAs. RESULTS: Coronary compression occurred in 9 (14%) of the 66 patients who underwent TPVR. Most CC cases (seven of nine) occurred in patients with conduits. Proximity of the right ventricular outflow tract (RVOT) landing zone to the coronary arteries and to the chest wall was a significant risk factor for compression (P < .001 and P = .019, respectively). Compression risk increased significantly if patients had an RVOT to coronary artery distance of ≤3 mm (P < .001) and an RVOT to chest wall distance of ≤8 mm (P = .026). Anomalous course of coronary arteries was another significant univariate risk factor (P = .003). CONCLUSIONS: Right ventricular outflow tract landing zone distance of ≤3 mm to a coronary artery, landing zone distance of ≤8 mm to the chest wall, and anomalous coronary arteries are associated with increased CC risk. Electrocardiogram gating may not be necessary if coronary arteries are opacified on CTAs. Larger studies are needed to explore and confirm these coronary artery compression risk factors.

Association between patient age at implant and outcomes after transcatheter pulmonary valve replacement in the multicenter Melody valve trials.

OBJECTIVES: To investigate whether age and valve size at implant contribute to outcomes after Melody transcatheter pulmonary valve replacement (TPVR). BACKGROUND: Patient age and valve size at implant contribute to longevity of surgical pulmonary valves. METHODS: All patients discharged with a Melody valve in the pulmonary position, as part of three prospective Melody valve multicenter studies, comprised the study cohort. Acute and time-related outcomes were analyzed according to age: children (≤12 years), adolescents (13-18 years), young adults (19-29 years), and older adults (≥30 years). RESULTS: Successful Melody valve implantation occurred in 49 children, 107 adolescents, 96 young adults, and 57 older adults. Pediatric patients (≤18 years) were more likely to have TPVR for conduit stenosis than adults (62% vs. 44%); children had the smallest conduits. After TPVR, pediatric and adult patients had similar decreases in right ventricular (RV) size by MRI, but adults had improved percentage predicted peak VO2 (58% preimplant to 64% postimplant, p = .02) and FEV1 (69% pre to 71% post, p = .005). Younger age was associated with shorter freedom from RVOT dysfunction, reintervention, and explant. Children had the shortest freedom from endocarditis (p = .041), but all other groups had 5-year freedom from endocarditis of ≥90%. CONCLUSIONS: Younger age was associated with shorter time to RVOT dysfunction, reintervention, and explant after Melody TPVR. Patients ≥13 years of age were at low risk for endocarditis and explant to 5 years. A better understanding of time-related outcomes by age will aid in the comparison of therapeutic options for TPVR candidates. CLINICAL TRIAL REGISTRATION: https://clinicaltrials.gov/ct2/show/NCT00740870 (NCT00740870), https://clinicaltrials.gov/ct2/show/NCT01186692 (NCT01186692), and https://clinicaltrials.gov/ct2/show/NCT00688571 (NCT00688571).

Gene Delivery for Limb-Girdle Muscular Dystrophy Type 2D by Isolated Limb Infusion.

In a previous limb-girdle muscular dystrophy type 2D (LGMD2D) clinical trial, robust alpha-sarcoglycan gene expression was confirmed following intramuscular gene (SGCA) transfer. This paved the way for first-in-human isolated limb infusion (ILI) gene transfer trial to the lower limbs. Delivery of scAAVrh74.tMCK.hSGCA via an intravascular route through the femoral artery predicted improved ambulation. This method was initially chosen to avoid safety concerns required for large systemic vascular delivery viral loads. ILI methods were adopted from the extensive chemotherapy experience for treatment of malignancies confined to the extremities. Six LGMD2D subjects were enrolled in a dose-ascending open-label clinical trial. Safety of the procedure was initially assessed in the single limb of a non-ambulant affected adult at a dose of 1 × 1012 vg/kg. Subsequently, ambulatory children (aged 8-13 years) were enrolled and dosed bilaterally with either 1 × 1012 vg/kg/limb or 3 × 1012 vg/kg/limb. The six-minute walk test (6MWT) served as the primary clinical outcome; secondary outcomes included muscle strength (maximum voluntary isometric force testing) and SGCA expression at 6 months. All ambulatory participants except one had pre- and post-treatment muscle biopsies. All four subjects biopsied had confirmed SGCA gene delivery by immunofluorescence, Western blot analysis (14-25% of normal), and vector genome copies (5.4 × 103-7.7 × 104 vg/µg). Muscle strength in the knee extensors (assessed by force generation in kilograms) showed improvement in two subjects that correlated with an increase in fiber diameter post gene delivery. Six-minute walk times decreased or remained the same. Vascular delivery of AAVrh74.tMCK.hSGCA was effective at producing SGCA protein at low doses that correlated with vector copies and local functional improvement restricted to targeted muscles. Future trials will focus on systemic administration to enable targeting of proximal muscles to maximize clinical benefit.