Comparison of electrogram characteristics in persistent atrial fibrillation.

INTRODUCTION: Multiple analysis techniques evaluate electrograms during atrial fibrillation (AF), but none have been established to guide catheter ablation. This study compares electrogram properties recorded from multiple right (RA) and left atrial (LA) sites. METHODS: Multisite LA/RA mapping (281 ± 176/239 ± 166 sites/patient) was performed in 42 patients (30 males, age 63 ± 9 years) undergoing first (n = 32) or redo-AF ablation (n = 10). All electrogram recordings were visually reviewed and artifactual signals were excluded leaving a total of 21 846 for analysis. Electrogram characteristics evaluated were cycle length (CL), amplitude, Shannon's entropy (ShEn), fractionation interval, dominant frequency, organizational index, and cycle length of most recurrent morphology (CLR ) from morphology recurrence plot analysis. RESULTS: Electrogram characteristics were correlated to each other. All pairwise comparisons were significant (p < .001) except for dominant frequency and CLR (p = .59), and amplitude and dominant frequency (p = .38). Only ShEn and fractionation interval demonstrated a strong negative correlation (r = -.94). All other pairwise comparisons were poor to moderately correlated. The relationships are highly conserved among patients, in the RA versus LA, and in those undergoing initial versus redo ablations. Antiarrhythmic drug therapy did not have a significant effect on electrogram characteristics, except minimum ShEn. Electrogram characteristics associated with ablation outcome were shorter minimum CLR , lower minimum ShEn, and longer mimimum CL. There was minimal overlap between the top 10 sites identified by one electrogram characteristic and the top 10 sites identified by the other 10 characteristics. CONCLUSION: Multiple techniques can be employed for electrogram analysis in AF. In this analysis of eight different electrogram characteristics, seven were poorly to moderately correlated and do not identify similar locations. Only some characteristics were predictive of ablation outcome. Further studies to consider electrogram properties, perhaps in combination, for categorizing and/or mapping AF are warranted.

Electrogram morphology recurrence guided catheter ablation for repeat ablation of persistent atrial fibrillation.

BACKGROUND: There are no standard mapping approaches for patients with persistent atrial fibrillation (PeAF), particularly after failed prior catheter ablation (CA). In this study, we assess the feasibility of using Electrogram Morphology Recurrence (EMR) to guide ablation. METHODS: Ten patients with recurrent PeAF after prior CA underwent detailed mapping of both atria during PeAF using the PentaRay (4 mm interelectrode spacing) and 3D mapping with CARTO. At each site, 15 s recordings were made. Custom software identified each electrogram and cross-correlation was used to identify the most recurrent electrogram morphology from which the % recurrence and cycle length of the most repeatable morphology (CLR) was calculated. Sites of shortest CLR and sites within 5 ms of shortest CLR with recurrence ≥ 80% were used to inform CA strategy. RESULTS: A mean of 342.9 ± 131.9 LA and 328.6 ± 91.5 RA sites were recorded per patient. Nine had PV reconnection. Shortest CLR sites guided ablation in 6/10 patients while 1 patient failed to fulfill shortest CLR criteria, and another 3 did not undergo CA guided by shortest CLR due to operator preference. On 12-month follow-up, all 4 patients without shortest CLR guided CA had recurrent PeAF. Of the 6 patients with shortest CLR guided CA, 5 patients did not have recurrent PeAF (p = 0.048), although 1 had paroxysmal AF and 2 had atypical atrial flutter. CONCLUSION: EMR is a feasible, novel technique to guide CA in patients with PeAF. Further evaluation is needed to provide an electrogram-based method for mapping guided targeted ablation of key areas.

Electrogram Morphology Recurrence for Mapping Persistent Atrial Fibrillation: Initial vs Redo Catheter Ablation.

BACKGROUND: Electrogram (EGM) morphology recurrence (EMR) mapping of persistent atrial fibrillation (AF) quantifies consistency of activation and is expected to be high and rapid near AF drivers. OBJECTIVES: The purpose of this study was to compare EMR in left atria (LA) and right atria (RA) in patients undergoing first vs redo ablation for persistent AF. METHODS: Multisite LA/RA mapping (LA: 281 ± 176 sites/patient; RA: 239 ± 166 sites/patient) before persistent AF ablation was performed in 42 patients (30 males, age 63 ± 9 years) undergoing first (Group 1, n = 32) or redo ablation (Group 2, n = 10). After cross-correlation of each automatically detected EGM with every other EGM per recording, the most recurrent electrogram morphology was identified and its frequency (Rec%) and recurrence cycle length (CLR) were computed. RESULTS: In Groups 1 and 2, minimum CLR was 172.8 ± 26.0 milliseconds (LA: 178.2 ± 37.6 milliseconds, RA: 204.4 ± 34.0 milliseconds, P = 0.0005) and 186.5 ± 28.3 milliseconds (LA: 196.1 ± 38.1 milliseconds vs RA: 199.0 ± 30.2 milliseconds, P = 0.75), with Rec% 94.7% ± 10% and 93.8% ± 9.2%. Group 2 minimum CLR was not different from Group 1 (P = 0.20). Shortest CLR was in the LA in 84% of Group 1 and 50% of Group 2 patients (P = 0.04). Only 1 of 10 patients in Group 2 had the shortest CLR in the pulmonary veins (PVs) compared with 19 of 32 in Group 1 (P = 0.01). Most sites (77.6%) had Rec% <50%. CONCLUSIONS: EMR identified the shortest CLR sites in the PVs in 59% of patients undergoing initial persistent AF ablation, consistent with reported success rates of ∼50% for PV isolation. The majority of sites have low recurrence and may reflect bystander sites not critical for maintaining AF. EMR provides a robust new method for quantifying consistency and rapidity of activation direction at multiple atrial sites.

A novel temporary atrioventricular sequential pacing catheter-Characteristics and first-in-human application.

BACKGROUND: Sequential synchronized atrioventricular (AV) pacing provides enhanced electrophysiologic parameters which contribute to improved hemodynamic parameters and increased cardiac performance to subsequently confer a clinical advantage over traditional ventricular pacing. Current temporary transvenous pacemaker catheters are limited to only one electrode which paces solely the right ventricle, thus lacking the capability to provide the optimal pacing mode. A new multilead pacemaker device was developed in response to the need for improved temporary pacing through the utilization of sequential synchronized atrioventricular pacing (TAVSP). It consists of seven preformed, preshaped nitinol wires electrodes, of which four are for intra-atrial and three for intraventricular positioning and endocardial contact, respectively. Each wire carries a ball tip designed to minimize tissue trauma and provide a high current density for adequate myocardial capture. The device is not yet Food and Drug Administration approved. OBJECTIVE: To present the unique structural components and mechanical properties of a novel sequential synchronized AV pacing device for temporary insertion and to report its first-in-human application with an analysis of the early clinical experience. METHODS: Following a process of development and proof of concept of the novel pacing modality in an animal model which demonstrated feasibility and safety, a series of patients who were candidates for the device application was identified. During left and right heart catheterization, the novel temporary pacing catheter was inserted transvenously and delivered in most patients under fluoroscopy or echocardiography. The catheter was deployed to its target right heart anatomic sites and then activated in an AV sequential mode. The technical aspects, the corresponding clinical utilization, and device performance were documented and analyzed. RESULTS: The series included 10 enrolled subjects. During planned left and right heart catheterization, the novel TAVSP device was inserted transvenously and then delivered and deployed successfully in a timely fashion in all patients. The pacing catheter achieved proper threshold and impedance in all (100%) patients. The performance of all ventricular leads was adequate; however, in 1 (10%) patient poor performance of the atrial leads was detected. The device was successfully retrieved in all patients. No adverse arrhythmia, impaired hemodynamics, or clinical adverse events occurred. No technical difficulties, component failure, or wires thrombosis were detected. All patients sustained the device application without sequala and were discharged home. CONCLUSION: Initial clinical experience with the utilization of a novel TAVSP demonstrates feasibility and safety in humans. The TAVSP modality potentially offers improved pacing capability and subsequent hemodynamic benefits over the current temporary pacing catheters. Further experience with the clinical application of this pacing catheter is warranted.

Long-term cardiac surveillance and outcomes of COVID-19 patients.

Acute cardiac manifestions of COVID-19 have been well described, while chronic cardiac sequelae remain less clear. Various studies have shown conflicting data on the prevalence of new or worsening cardiovascular disease, myocarditis or cardiac dysrhythmias among patients recovered from COVID-19. Data are emerging that show that patients recovering from COVID-19 have an increased incidence of myocarditis and arrhythmias after recovery from COVID-19 compared with the control groups without COVID-19. The incidence of myocarditis after COVID-19 infection is low but is still significantly greater than the incidence of myocarditis from a COVID-19 vaccine. There have been several studies of athletes who underwent a variety of screening protocols prior to being cleared to return to exercise and competition. The data show possible, probable or definite myocarditis or cardiac injury among 0.4-3.0% of the athletes studied. Recent consensus statements suggest that athletes with full recovery and absence of cardiopulmonary symptoms may return to exercise and competition without cardiovascular testing. In conclusion, patients with COVID-19 may be expected to have an increased risk of cardiovascular disease, myocarditis or arrhythmias during the convalescent phase. Fortunately, the majority of patients, including athletes may return to their normal activity after recovery from COVID 19, in the absence of persisting cardiovascular symptoms.

Early trends in leadless pacemaker implantation: Evaluating nationwide in-hospital outcomes.

BACKGROUND: Single-chamber leadless intracardiac pacemaker (LICP) implantation was approved in 2016 in the United States. However, little is known regarding trends in real-world utilization and complication rates. OBJECTIVE: The purpose of this study was to assess nationwide demographics, trends, and outcomes among hospitalizations with LICP implantation in the United States. METHODS: Using the National Inpatient Sample, we identified all hospitalizations with LICP or transvenous pacemaker implantation as a comparator between 2017 and 2019. We evaluated baseline patient characteristics, admitting diagnoses, procedural complications, lengths of stay, discharge dispositions, and all-cause mortality. RESULTS: The majority of LICP recipients were elderly (75.4 ± 12.8 years), male (55.2%), and White (76.8%) compared to Black (9.8%), or Hispanic (7.3%). Between 2017 and 2019, the average age increased along with the prevalence of heart failure, atrial fibrillation, and malignancy among recipients. Most hospitalizations were emergent (84.5%). Between 2017 and 2019, pooled procedural complications decreased significantly (10.8% vs 7.9%; P <.001), primarily due to declining infection and device retrieval rates. In-hospital mortality also decreased significantly (8.2% vs 4.2%; P <.001). History of cardiogenic shock or cardiac device infection was associated with the greatest mortality or complication risk. Compared to transvenous pacemaker, LICP implantation was associated with lower complication rates (8.6% vs 11.2%) but greater mortality (5.2% vs 1.3%; P <.001). CONCLUSION: Nationwide LICP implantations were performed in patients of increasing age, comorbidities, and acuity of illness. In-hospital mortality and procedure-related complications declined in the first 3 years after approval of LICP implantation and may reflect improving operator experience. Increased mortality compared with transvenous pacemaker implant remains a concern.

The Cost of Return to Play Protocols in Collegiate Athletes Recovering from Coronavirus Disease 2019.

INTRODUCTION/PURPOSE: SARS-CoV-2 infection (COVID-19) can result in myocarditis. Protocols were developed to allow competitive athletes to safely return to play (RTP) after a COVID-19 infection, but the financial impact of these protocols is unknown. Our objective was to determine the differential cost of post-COVID-19 RTP protocols for competitive collegiate athletes. METHODS: This multicenter retrospective cohort study of clinical evaluation of 295 athletes after COVID-19 infection was performed at four institutions with three RTP protocols. Costs were calculated using adjusted Center for Medicare and Medicaid Services pricing. All athletes underwent electrocardiogram and clinical evaluation. A tiered approach performed cardiac imaging and biomarker analysis for major symptoms. A universal transthoracic echocardiogram (TTE) approach performed TTE and biomarkers for all athletes. A universal exercise stress echocardiogram (ESE) approach performed ESE and biomarkers for all athletes. RESULTS: The cost per athlete was $632.51 ± 651.80 ($44,908 total) in tiered group (n = 71), $1,072.30 ± 517.93 ($87,928 total) in the universal TTE group (n = 82), and $1357.38 ± 757.05 ($192,748 total) in the universal ESE group (n = 142) (P < 0.001). Extrapolated national costs for collegiate athletes would be $39 to 64 million higher for universal imaging approaches versus a tiered approach. Only seven athletes had probable/possible myocarditis with no significant difference between approaches. CONCLUSIONS: Cardiac screening in collegiate athletes after COVID-19 infection resulted in significant cost to the health care system. A tiered-based approach was more economical, and a universal exercise echocardiogram group detected slightly more myocardial abnormalities by cardiac magnetic resonance imaging. The clinical consequences of these approaches are unknown.

A Phase II study of autologous mesenchymal stromal cells and c-kit positive cardiac cells, alone or in combination, in patients with ischaemic heart failure: the CCTRN CONCERT-HF trial.

AIMS: CONCERT-HF is an NHLBI-sponsored, double-blind, placebo-controlled, Phase II trial designed to determine whether treatment with autologous bone marrow-derived mesenchymal stromal cells (MSCs) and c-kit positive cardiac cells (CPCs), given alone or in combination, is feasible, safe, and beneficial in patients with heart failure (HF) caused by ischaemic cardiomyopathy. METHODS AND RESULTS: Patients were randomized (1:1:1:1) to transendocardial injection of MSCs combined with CPCs, MSCs alone, CPCs alone, or placebo, and followed for 12 months. Seven centres enrolled 125 participants with left ventricular ejection fraction of 28.6 ± 6.1% and scar size 19.4 ± 5.8%, in New York Heart Association class II or III. The proportion of major adverse cardiac events (MACE) was significantly decreased by CPCs alone (-22% vs. placebo, P = 0.043). Quality of life (Minnesota Living with Heart Failure Questionnaire score) was significantly improved by MSCs alone (P = 0.050) and MSCs + CPCs (P = 0.023) vs. placebo. Left ventricular ejection fraction, left ventricular volumes, scar size, 6-min walking distance, and peak oxygen consumption did not differ significantly among groups. CONCLUSIONS: This is the first multicentre trial assessing CPCs and a combination of two cell types from different tissues in HF patients. The results show that treatment is safe and feasible. Even with maximal guideline-directed therapy, both CPCs and MSCs were associated with improved clinical outcomes (MACE and quality of life, respectively) in ischaemic HF without affecting left ventricular function or structure, suggesting possible systemic or paracrine cellular mechanisms. Combining MSCs with CPCs was associated with improvement in both these outcomes. These results suggest potential important beneficial effects of CPCs and MSCs and support further investigation in HF patients.

Association of SGLT2 inhibitors with arrhythmias and sudden cardiac death in patients with type 2 diabetes or heart failure: A meta-analysis of 34 randomized controlled trials.

BACKGROUND: Sodium-glucose cotransporter 2 inhibitors (SGLT2is) reduce hospitalizations and death from heart failure (HF), but their effect on arrhythmia expression has been poorly investigated. OBJECTIVE: The purpose of this study was to evaluate the association of SGLT2is with arrhythmias in patients with type 2 diabetes mellitus (T2DM) or HF. METHODS: We searched PubMed and ClinicalTrials.gov. Two independent investigators identified randomized double-blind trials that compared SGLT2is with placebo or active control for adults with T2DM or HF. Primary outcomes were incident atrial arrhythmias, ventricular arrhythmias (VAs), and sudden cardiac death (SCD). RESULTS: We included 34 randomized (25 placebo-controlled and 9 active-controlled) trials with 63,166 patients (35,883 SGLT2is vs 27,273 control: mean age 53-67 years; 63% male). Medications included canagliflozin, dapagliflozin, empagliflozin, or ertugliflozin. Except for 1 study of HF, all patients had T2DM. Follow-up ranged from 24 weeks to 5.7 years. The cumulative incidence of events was low: 3.6, 1.4, and 2.5 per 1000 patient-years for atrial arrhythmias, VAs and SCD, respectively. SGLT2i therapy was associated with a significant reduction in the risk of incident atrial arrhythmias (odds ratio 0.81; 95% confidence interval 0.69-0.95; P = .008) and the "SCD" component of the SCD outcome (odds ratio 0.72; 95% confidence interval 0.54-0.97; P = .03) compared with control. There was no significant difference in incident VA or the "cardiac arrest" SCD component between groups. CONCLUSION: SGLT2is are associated with significantly reduced risks of incident atrial arrhythmias and SCD in patients with T2DM. Prospective trials are warranted to confirm the antiarrhythmic effect of SGLT2is and whether this is a class or drug-specific effect.

Demographic representation in clinical trials for cell-based therapy.

Inclusion of women and minorities in clinical research is critical to fully assess the safety and efficacy of innovative therapies. With inadequate representation of demography, generalizability is impaired since pharmacokinetics and pharmacodynamics differ in these patient populations. This study was designed to analyze the voluntary participation rates of different demographic groups in cell-based therapy clinical trials conducted by the Interdisciplinary Stem Cell Institute (ISCI) at the University of Miami, Miller School of Medicine. ISCI conducted eight clinical trials between 2007 and 2017. The trials enrolled patients with ischemic and non-ischemic cardiomyopathy, idiopathic pulmonary fibrosis (IPF), aging-frailty, and Type-2 Diabetes. Participants received cell-based therapy (n = 218) or placebo (n = 33). Among the 251 participants, 29.5% were Hispanic and 20% were women. The proportion of individuals participating in each trial was compared to that of the respective disease populations attending University of Miami Health System clinics to calculate the participation to prevalence ratio (PPR). Distribution of women accurately reflected the population attending the University of Miami Health System in trials for dilated cardiomyopathy (DCM) and aging-frailty but was under-represented in others. Similarly, Hispanics and whites were accurately represented in three of the five disease fields, with Hispanics under-represented in frailty and diabetes, and whites over-represented in DCM and IPF. Black patients were accurately represented in the diabetes trial but were under-represented in all others. This study provides insight into challenges of achieving representative inclusion in research. Novel community engagement strategies are necessary to improve inclusion of women and under-represented minorities in clinical research of cell-based therapy.

Atrial Myopathy Underlying Atrial Fibrillation.

While AF most often occurs in the setting of atrial disease, current assessment and treatment of patients with AF does not focus on the extent of the atrial myopathy that serves as the substrate for this arrhythmia. Atrial myopathy, in particular atrial fibrosis, may initiate a vicious cycle in which atrial myopathy leads to AF, which in turn leads to a worsening myopathy. Various techniques, including ECG, plasma biomarkers, electroanatomical voltage mapping, echocardiography, and cardiac MRI, can help to identify and quantify aspects of the atrial myopathy. Current therapies, such as catheter ablation, do not directly address the underlying atrial myopathy. There is emerging research showing that by targeting this myopathy we can help decrease the occurrence and burden of AF.

COVID-19 cardiac injury: Implications for long-term surveillance and outcomes in survivors.

Up to 20%-30% of patients hospitalized with coronavirus disease 2019 (COVID-19) have evidence of myocardial involvement. Acute cardiac injury in patients hospitalized with COVID-19 is associated with higher morbidity and mortality. There are no data on how acute treatment of COVID-19 may affect the convalescent phase or long-term cardiac recovery and function. Myocarditis from other viral pathogens can evolve into overt or subclinical myocardial dysfunction, and sudden death has been described in the convalescent phase of viral myocarditis. This raises concerns for patients recovering from COVID-19. Some patients will have subclinical and possibly overt cardiovascular abnormalities. Patients with ostensibly recovered cardiac function may still be at risk of cardiomyopathy and cardiac arrhythmias. Screening for residual cardiac involvement in the convalescent phase for patients recovered from COVID-19-associated cardiac injury is needed. The type of testing and therapies for post COVID-19 myocardial dysfunction will need to be determined. Therefore, now is the time to plan for appropriate registries and clinical trials to properly assess these issues and prepare for long-term sequelae of "post-COVID-19 cardiac syndrome."

Network meta-analysis of His bundle, biventricular, or right ventricular pacing as a primary strategy for advanced atrioventricular conduction disease with normal or mildly reduced ejection fraction.

INTRODUCTION: Although right ventricular pacing (RVP) may impair ventricular function, it is commonly used for advanced atrioventricular block (AVB) and normal or mildly reduced ejection fraction (EF). We aimed to compare His bundle pacing (HBP), biventricular pacing (BiVP), and RVP for advanced AVB in patients with normal or mildly reduced EF. METHODS AND RESULTS: MEDLINE, Embase, Cochrane CENTRAL, ClinicalTrials.gov, Scopus, and Web of Science were searched. Outcomes were all-cause death, heart failure hospitalizations (HFH), EF, left ventricular volumes, 6-minute walk test, and QRS duration. HBP or BiVP was compared with RVP. Subsequently, network meta-analysis compared the three pacing options. Our protocol was registered in PROSPERO (CRD42018094132). Six studies compared BiVP and RVP (704 vs 614 patients) and four compared HBP and RVP (463 vs 568 patients). Follow-up was 6 months to 5 years. There was significantly lower mortality and HFH with HBP or BiVP as compared with RVP (odds ratio [OR], 0.66, [0.51-0.85], P = .002; OR, 0.61 [0.45-0.82], P < .001, respectively]. HBP or BiVP also showed significant increase in EF and decrease in QRS duration (mean difference [MD], 5.27 [3.86-6.69], P < .001; MD -42.2 [-51.2 to -33.3], P < .001, respectively). In network meta-analysis, HBP and BiVP were associated with significantly improved survival compared to RVP, with surface under the cumulative ranking curve (SUCRA) probability of 79.4%, 69.4%, and 1.2% for HBP, BiVP, and RVP, respectively. For HFH, SUCRA probability was 91.5%, 57.2%, and 1.3%, respectively. CONCLUSION: HBP or BiVP were the superior strategies to reduce all-cause death and HFH for advanced AVB with normal or mildly reduced EF, with no significant difference between BiVP and HBP.

The impact of patient sex on the response to intramyocardial mesenchymal stem cell administration in patients with non-ischaemic dilated cardiomyopathy.

AIMS: Sex differences impact the occurrence, presentation, prognosis, and response to therapy in heart disease. Particularly, the phenotypic presentation of patients with non-ischaemic dilated cardiomyopathy (NIDCM) differs between men and women. However, whether the response to mesenchymal stem cell (MSC) therapy is influenced by sex remains unknown. We hypothesize that males and females with NIDCM respond similarly to MSC therapy. METHODS AND RESULTS: Male (n = 24) and female (n = 10) patients from the POSEIDON-DCM trial who received MSCs via transendocardial injections were evaluated over 12 months. Endothelial function was measured at baseline and 3 months post-transendocardial stem cell injection (TESI). At baseline, ejection fraction (EF) was lower (P = 0.004) and end-diastolic volume (EDV; P = 0.0002) and end-systolic volume (ESV; P = 0.0002) were higher in males vs. females. In contrast, baseline demographic characteristics, Minnesota Living with Heart Failure Questionnaire (MLHFQ), and 6-min walk test (6MWT) were similar between groups. EF improved in males by 6.2 units (P = 0.04) and in females by 8.6 units (P = 0.04; males vs. females, P = 0.57). EDV and ESV were unchanged over time. The MLHFQ score, New York Heart Association (NYHA) class, endothelial progenitor cell-colony forming units, and serum tumour necrosis factor alpha improved similarly in both groups. CONCLUSION: Despite major differences in phenotypic presentation of NIDCM in males and females, this study is the first of its kind to demonstrate that MSC therapy improves a variety of parameters in NIDCM irrespective of patient sex. These findings have important clinical and pathophysiologic implications regarding the impact of sex on responses to cell-based therapy for NIDCM.

Allogeneic Mesenchymal Cell Therapy in Anthracycline-Induced Cardiomyopathy Heart Failure Patients: The CCTRN SENECA Trial.

BACKGROUND: Anthracycline-induced cardiomyopathy (AIC) may be irreversible with a poor prognosis, disproportionately affecting women and young adults. Administration of allogeneic bone marrow-derived mesenchymal stromal cells (allo-MSCs) is a promising approach to heart failure (HF) treatment. OBJECTIVES: SENECA (Stem Cell Injection in Cancer Survivors) was a phase 1 study of allo-MSCs in AIC. METHODS: Cancer survivors with chronic AIC (mean age 56.6 years; 68% women; NT-proBNP 1,426 pg/ml; 6 enrolled in an open-label, lead-in phase and 31 subjects randomized 1:1) received 1 × 108 allo-MSCs or vehicle transendocardially. Primary objectives were safety and feasibility. Secondary efficacy measures included cardiac function and structure measured by cardiac magnetic resonance imaging (CMR), functional capacity, quality of life (Minnesota Living with Heart Failure Questionnaire), and biomarkers. RESULTS: A total of 97% of subjects underwent successful study product injections; all allo-MSC-assigned subjects received the target dose of cells. Follow-up visits were well-attended (92%) with successful collection of endpoints in 94% at the 1-year visit. Although 58% of subjects had non-CMR compatible devices, CMR endpoints were successfully collected in 84% of subjects imaged at 1 year. No new tumors were reported. There were no significant differences between allo-MSC and vehicle groups with regard to clinical outcomes. Secondary measures included 6-min walk test (p = 0.056) and Minnesota Living with Heart Failure Questionnaire score (p = 0.048), which tended to favor the allo-MSC group. CONCLUSIONS: In this first-in-human study of cell therapy in patients with AIC, transendocardial administration of allo-MSCs appears safe and feasible, and CMR was successfully performed in the majority of the HF patients with devices. This study lays the groundwork for phase 2 trials aimed at assessing efficacy of cell therapy in patients with AIC.

Genetic determinants of responsiveness to mesenchymal stem cell injections in non-ischemic dilated cardiomyopathy.

BACKGROUND: Non-ischemic dilated cardiomyopathy (NIDCM) responds variably to intramyocardial injection of mesenchymal stem cells (MSCs). We hypothesized that NIDCM genotype may influence responsiveness to MSC therapy and performed genotyping on all patients in the POSEIDON-DCM trial. METHODS: POSEIDON-DCM patients (n = 34) underwent genetic sequence analysis and deletion/duplication testing. The results were classified as positive for pathological variants (PV+; n = 8), negative for any variants (V-; n = 6), or as variants of uncertain significance (VUS; n = 20). All outcomes of therapy were analysed for each category of genetic results. FINDINGS: The 3 groups were indistinguishable at baseline with regard to ejection fraction (EF), demographics, medication use, or functional parameters. V- patients had an increase in EF at 12 months: +13.6% (IQR = +7.8%; +20.5%; p = 0.002), compared with VUS (+6.5%; IQR = +0.9%, +11.1%; p = 0.005) and PV+(-5.9%; IQR = -12.7%, +1.0; p = 0.2; p = 0.01 between groups). Six-minute walk distance improved in V- patients, but not in VUS and PV+. V- patients improved MLHFQ, compared to the other 2 groups, which did not improve over time. EPCCFUs increased by 9.7 ±â€¯1.9 in V- (p = 0.009) compared to VUS and PV+ patients. V- patients had one-year survival (100%) compared with VUS (85%) and PV+ (40%; p = 0.015 log-rank). Similarly, MACE rates were lower in V- (0%) than PV+ (61.9%) or VUS (42.2%; p = 0.021 log-rank). INTERPRETATION: Our findings support the concept that the genetic profile of NIDCM patients plays a role in responsiveness to MSC therapy, with V- patients more likely to benefit and the converse for PV+. This observation emphasizes the need for further genetic studies, because of important implications for the management of NIDCM syndromes.

A meta-analysis of arrhythmia endpoints in randomized controlled trials of transendocardial stem cell injections for chronic ischemic heart disease.

INTRODUCTION: The electrophysiologic impact of cell-based therapy on the injured myocardium remains highly controversial. We aimed to perform a meta-analysis of studies comparing arrhythmia burden following transendocardial stem cell therapy vs placebo in patients with chronic ischemic heart disease (CIHD). METHODS AND RESULTS: PubMed, Embase, and Cochrane Central Register of Controlled Trials were searched. No restriction of stem cell type was specified. The outcomes included sustained supraventricular or ventricular arrhythmias (VAs), sudden cardiac death (SCD), and resuscitated sudden cardiac arrest (SCA). Effect sizes were reported as odds ratio (OR) and 95% CI. Poisson regression was used to account for zero-events data. Twelve randomized trials that included 736 patients (384 in the cell therapy group and 352 in the placebo group) were analyzed. Six different cell types were used. Follow-up ranged from 6 to 12 months. There was a significant decrease in risk of SCD in the cell therapy group, (FE OR, 0.19 [0.04, 0.93]; P = .04). In subgroup analysis, there was a significantly lower risk of SCD or resuscitated SCA in the cell therapy group limited to studies that did not use skeletal myoblasts, (FE OR, 0.23 [0.06, 0.83]; P = .03). There was no significant difference in the incidence of sustained VA between groups (FE OR, 0.91 [0.47, 1.77]; P = .8), even after stratifying by cell type. There was no difference in supraventricular arrhythmias between groups. CONCLUSION: Nonskeletal myoblast transendocardial cell therapy was associated with a significantly lower risk of SCD or resuscitated SCA compared to control, with no proarrhythmic effects.