Cardiac Myoediting Attenuates Cardiac Abnormalities in Human and Mouse Models of Duchenne Muscular Dystrophy.

[Figure: see text].

CRISPR/Cas correction of muscular dystrophies.

Muscular dystrophies are a heterogeneous group of monogenic neuromuscular disorders which lead to progressive muscle loss and degeneration of the musculoskeletal system. The genetic causes of muscular dystrophies are well characterized, but no effective treatments have been developed so far. The discovery and application of the CRISPR/Cas system for genome editing offers a new path for disease treatment with the potential to permanently correct genetic mutations. The post-mitotic and multinucleated features of skeletal muscle provide an ideal target for CRISPR/Cas therapeutic genome editing because correction of a subpopulation of nuclei can provide benefit to the whole myofiber. In this review, we provide an overview of the CRISPR/Cas system and its derivatives in genome editing, proposing potential CRISPR/Cas-based therapies to correct diverse muscular dystrophies, and we discuss challenges for translating CRISPR/Cas genome editing to a viable therapy for permanent correction of muscular dystrophies.

Symptom burden and treatment perception in patients with atrial fibrillation, with and without a family history of atrial fibrillation.

Atrial fibrillation (AF) is known to aggregate within family and might be associated with a lower quality-of-life (QoL). We evaluated the association between a family history (FHx) of AF and patient-reported symptom burden and perception towards treatment. We performed a retrospective analysis in a cohort of 1285 newly diagnosed patients with AF. Patients completed the atrial fibrillation effect on quality of life (AFEQT) questionnaire at the time of registration and at the 1-year follow-up. Patients who had a first-degree relative with AF were classified into the FHx group. Baseline characteristics and AFEQT scores were compared between groups, and a multivariate analysis was used to evaluate the independent association between FHx and QoL. Overall, 15.9% of patients (n = 204) had a positive AF FHx. Compared to the non-FHx group, the FHx group had an earlier onset of AF (60.2 ± 12.0 years vs. 64.5 ± 12.1 years; P < 0.05) and lower AFEQT overall summary (AFEQT-OS) score at baseline (73.9 ± 17.8 vs. 77.0 ± 16.8; P < 0.05). After adjustment for clinical background, a positive FHx was independently associated with a worse QoL (changes in AFEQT-OS score = - 3.18; 95% confidence interval: - 5.67 to - 0.69; P = 0.012). No between-group difference in AFEQT-OS scores was noted at the 1-year follow-up. An FHx of AF was associated with a lower QoL, which could be improved by therapeutic intervention in patients with AF. Recognizing the presence of an FHx of AF is important to predict patient's symptom load and treatment acceptance.

Discrepancy in recognition of symptom burden among patients with atrial fibrillation.

Our aim was to investigate the variability in physician recognition of atrial fibrillation (AF)-related symptoms, which greatly contributes to the management of AF patients. METHODS AND RESULTS: A total of 1493 newly-referredAF patients (67 ±â€¯11 y/o, 1057 men) consecutively registered in an outpatient-based Japanese multicenter database (KiCS-AF) from September 2012 to December 2016 were analyzed. Self-reportedAF symptom burden was assessed via symptom and daily activities domains within the Atrial Fibrillation Effect on QualiTy-of-life (AFEQT) questionnaire. Physician symptom under-recognition (UR) was defined as no subjective complaints recorded in the medical records despite AFEQT score of <80; and physician's apparent over-recognition (OvR) was defined as documentation of subjective complaints despite total AFEQT score of ≥80. There was poor agreement between patient-reported and physicians-estimated symptom burden (kappa 0.28, 95% CI 0.23 to 0.33). In the logistic regression analysis, age> 75 (odds ratio [OR], 1.72; 95% confidence interval [CI], 1.13-2.62), male sex (OR, 1.82; 95% CI, 1.22-2.74), and persistent/permanent AF (OR 2.54/3.36; CI, 1.63-3.99/1.91-5.89, respectively) were predictors of UR. Conversely, heart failure (OR, 2.46; 95% CI, 1.44-4.25) and treatment in an ablation facility (OR, 1.43; 95% CI, 1.02-2.02) were associated with greater odds of OvR in addition to age, sex, and type of AF. CONCLUSIONS: Discordance in recognition of AF symptom burden by physicians was frequent in AF patients seen in outpatient management and involved both patient- and physician-related factors.

A high BNP level predicts an improvement in exercise tolerance after a successful catheter ablation of persistent atrial fibrillation.

INTRODUCTION: Restoration of sinus rhythm (SR) by catheter ablation (CA) of atrial fibrillation (AF) improves exercise tolerance. However, it is still unclear what characteristics of patients are contributing to an improvement in exercise tolerance after CA of AF without heart failure. METHODS AND RESULTS: This study consisted of 51 consecutive patients with persistent or long-standing persistent AF without heart failure who were restored to SR for over 6 months by a successful CA. Exercise tolerance was evaluated by cardiopulmonary exercise testing before and 3 and 6 months after CA. The clinical characteristics contributing to an improvement in exercise tolerance was elucidated. The peak oxygen uptake (VO2 )% significantly increased from 101.4 ± 20.3% to 110.9 ± 19.9% 3 months after the CA (P < .001). The improvement rate in the peak VO2 % exhibited a positive correlation to the baseline brain natriuretic peptide (BNP; ρ = 0.39, P < .01), but not to the age, AF duration, left ventricular ejection fraction, or left atrial size. The linear regression analysis revealed that the baseline BNP was an independent predictor of an improvement in the peak VO2 % (coefficients = 0.32; 95% confidence interval = 0.08, 0.54; P = .01). The peak VO2 % improved significantly in the patients whose baseline BNP level was greater than 100 pg/mL, compared to the others (P < .01). These favorable findings were also observed 6 months after the CA. CONCLUSION: Elimination of persistent AF by CA was associated with an improvement in exercise tolerance. This was particularly true in patients with high BNP values at baseline.

Importance of the vein of Marshall involvement in mitral isthmus ablation.

BACKGROUND: Epicardiac conduction via the vein of Marshall (VOM) can bypass the mitral isthmus (MI) line, making MI ablation difficult. This study aimed to assess the contribution of the VOM in achieving MI conduction block. METHODS: This study included 143 consecutive patients with nonparoxysmal atrial fibrillation who underwent initial MI ablation. They were retrospectively classified into two groups, a VOM-guided group (n = 28) and a conventional group (n = 115), according to the use of a 2-Fr electrode catheter inserted in the VOM. The acute success rate of achieving MI block and the ablation data were assessed. When the bidirectional block was verified exclusively in the VOM or coronary sinus (CS) electrodes, we defined it as a pseudo MI block. In the VOM-guided group, we ascertained the complete MI block, verified both in the VOM and CS electrodes. RESULTS: In the VOM-guided group, the pseudoblock was observed in 33.3% of the patients during MI ablation. With significantly less radiofrequency energy (19 322.6 ± 11 352.8 vs 25 389.3 ± 19 951.9, P = 0.04), we achieved a similar level of success rate in MI ablation in the VOM-guided group (96.4% vs 91.3%, P = 0.36). Notably, after achieving complete MI block, atrial burst pacing induced two perimitral flutters in the VOM-guided group, which were successfully terminated by the additional radiofrequency application. CONCLUSIONS: Assessment of electrical conduction through the VOM could clarify the existence of a pseudo MI conduction block. However, the existence of a slow conduction through the MI could be detected only after induction of perimitral atrial tachycardia with atrial programmed stimulation.

The Durability of Atrial Fibrillation Ablation Using an Oesophageal Temperature Cut-Off of 38°C.

BACKGROUND: A lower cut-off of the oesophageal temperature (ET) during catheter ablation of atrial fibrillation (AF) should be safer, but its durability may become in question. We evaluated an ET cut-off of 38°C with an output of 25W on the posterior wall. METHODS: In 636 consecutive patients (age: 60±10years, male: 542, paroxysmal AF: 405, CHADS2 score: 0.7±0.9), an ET probe was utilised in 303 patients (259 pulmonary vein isolations [PVIs] and 44 simultaneous isolations of the posterior wall and all PVs box isolations [BOXIs]). When the ET increased to >38°C, the radiofrequency delivery was switched off and the ablation point was tagged as an "EsoTag" by the CARTO™ system (Biosense Webster, Irvine, CA, USA). We analysed the characteristics of the ablation lesions at the EsoTags with respect to the dormant conduction, gaps in the redo-session, and ablation outcome. RESULTS: EsoTags were identified in 94.6% of the left PVIs and all BOXIs, and dormant conduction at the EsoTags was identified in 12.0% and 6.8%, respectively. In 10,796 ablation points, the ablation at the EsoTags that were associated with dormant conduction had a significantly shorter duration, smaller force-time integral, and smaller Δimpedance. The duration of an ET of >38°C was significantly and positively correlated with the body mass index and negatively with the left atrial appendage flow velocity. During the redo-sessions in a 10.5±6.0months of follow-up (PVI: 14.7%, BOXI: 11.4%), reconnections at the EsoTags with dormant conduction were observed only in two patients after the PVI. The AF survival rate did not significantly differ in the presence of dormant conduction at the EsoTags (83.1% vs. 75.0%, p=0.696). There were no patients hospitalised for gastroparesis. CONCLUSIONS: Atrial fibrillation ablation utilising an oesophageal temperature cut-off of 38°C might be safe and durable.

MiR-133 promotes cardiac reprogramming by directly repressing Snai1 and silencing fibroblast signatures.

Fibroblasts can be directly reprogrammed into cardiomyocyte-like cells (iCMs) by overexpression of cardiac transcription factors or microRNAs. However, induction of functional cardiomyocytes is inefficient, and molecular mechanisms of direct reprogramming remain undefined. Here, we demonstrate that addition of miR-133a (miR-133) to Gata4, Mef2c, and Tbx5 (GMT) or GMT plus Mesp1 and Myocd improved cardiac reprogramming from mouse or human fibroblasts by directly repressing Snai1, a master regulator of epithelial-to-mesenchymal transition. MiR-133 overexpression with GMT generated sevenfold more beating iCMs from mouse embryonic fibroblasts and shortened the duration to induce beating cells from 30 to 10 days, compared to GMT alone. Snai1 knockdown suppressed fibroblast genes, upregulated cardiac gene expression, and induced more contracting iCMs with GMT transduction, recapitulating the effects of miR-133 overexpression. In contrast, overexpression of Snai1 in GMT/miR-133-transduced cells maintained fibroblast signatures and inhibited generation of beating iCMs. MiR-133-mediated Snai1 repression was also critical for cardiac reprogramming in adult mouse and human cardiac fibroblasts. Thus, silencing fibroblast signatures, mediated by miR-133/Snai1, is a key molecular roadblock during cardiac reprogramming.

Discrimination between QRS and T Waves Using a Right Parasternal Lead for S-ICD in a Patient with a Single Ventricle.

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is a useful option for patients with a single ventricle (SV) in which transvenous leads are contraindicated because of intracardiac shunts. We report a case in which a right parasternal lead placement was indicated for an S-ICD in a resuscitated patient with an SV. There were significant changes in the magnitude of R to T waves ratio in the right compared to the left parasternal lead position. Screening in the right parasternal position is effective for selecting appropriate patients with congenital heart disease for S-ICD implantations.

Assessment of atrial fibrillation ablation outcomes with clinic ECG, monthly 24-h Holter ECG, and twice-daily telemonitoring ECG.

Differences in the methodologies for evaluating atrial fibrillation (AF) ablation outcomes should be evaluated. In the present study, we compared the AF ablation outcomes among periodic clinic electrocardiography (ECG), 24-h Holter ECG, and telemonitoring ECG to evaluate the differences among these methods. In addition, we evaluated the AF-free survival rate for each method with different durations of the blanking period. A total of 30 AF patients were followed up for 6 months after initial catheter ablation, with clinic ECG on every clinic visit, monthly 24-h Holter ECG, and telemonitoring ECG twice daily and upon symptoms. AF relapse was defined as AF or atrial tachycardia detected with any of the methods. Two patients dropped out of the study, and 28 patients were followed up for 8.8 ± 2.7 months. Patients underwent 3.6 ± 0.8 clinic ECG, 5.1 ± 0.8 Holter ECG, and 273 ± 68 telemonitoring ECG examinations. During the first, second, third, fourth, fifth, and sixth months of follow-up, Holter ECG detected relapses in 11.1, 8.3, 11.5, 15.4, 4.2, and 4.8 % of patients and telemonitoring ECG detected relapses in 32.1, 25.0, 25.0, 17.9, 28.6, and 17.9 % of patients, respectively. When no duration was set for the blanking period, the AF-free survival rate was significantly lower with telemonitoring ECG (46.4 %) than with Holter ECG (78.6 %, P = 0.013) or clinic ECG (85.7 %, P = 0.002). In addition, when the duration of the blanking period was set to 3 months, the AF-free survival rate was significantly lower with telemonitoring ECG than with clinic ECG (92.9 vs. 71.4 %, P = 0.041). The AF ablation outcomes with twice-daily telemonitoring ECG might differ from those with clinic ECG when the duration of the blanking period is 0-3 months. A follow-up based solely on clinic ECG might underestimate AF recurrence.

Electrical superior vena cava isolation using photodynamic therapy in a canine model.

AIMS: With the new era of multi-tip radiofrequency or balloon ablation catheters replacing the point-to-point ablation strategy, we aimed to determine the feasibility of a ring-laser catheter ablation technology to electrically isolate the superior vena cava (SVC) by exploring the advantages of the limitless catheter tip size possibly with the photodynamic therapy (PDT)-mediated ablation. METHODS AND RESULTS: We developed a first-generation prototype of a circular-laser-mapping catheter by fitting a 7 cm plastic optical fibre onto a circular variable-loop Lasso™ mapping catheter. Following SVC venography, both the laser catheter and another ring catheter for monitoring the SVC potentials were placed at the SVC. After the systemic infusion of a photosensitizer (talaporfin sodium), we initiated the irradiation with an output of 1 W in three canines and 0.3 W in four. The creation of electrical isolation as well as occurrence of phrenic nerve injury, sinus node injury, and SVC stenosis were evaluated before, immediately after, and 1 month after the procedure. A PDT-mediated SVC isolation was successfully performed in all seven canines. The isolation was completed with a laser irradiation of 70.4 ± 71.4 J/cm under 30.9 ± 5.0 µg/mL of a photosensitizer without any sinus node injury, phrenic nerve palsy, or SVC stenosis in both the acute and chronic evaluations. The minimum isolation time of 270 s was not correlated with the laser input power or the photosensitizer concentration. CONCLUSION: The electrical SVC isolation was successfully and instantly achieved using the PDT laser-ring catheter without any complications.

Oral Nitrate Administration Ameliorates Cardiogenic Shock due to Eclipsed Mitral Regurgitation.

Eclipsed mitral regurgitation (MR) has been reported as transient massive functional MR caused by a sudden coaptation defect in the absence of left ventricular remodeling or epicardial coronary artery stenosis. Coronary spasm or microvascular dysfunction has been suggested to be associated with the pathogenesis. Here, we present a 68-year-old woman with eclipsed MR with cardiogenic shock ameliorated by nitrate. She was admitted for transient shock with massive functional MR. Transient MR was associated with a complete absence of mitral leaflet coaptation owing to tethering of the lateral posterior mitral leaflet. The leaflet tethering was triggered by transient myocardial ischemia around the anterolateral papillary muscle, which could have been caused by coronary spasm and/or microvascular dysfunction. During admission, she experienced similar repeated episodes, which were ameliorated by oral nitrate administration. This is the first described case of eclipsed MR with shock ameliorated by nitrate. Although eclipsed MR, a cause of life-threatening shock, is uncommon, we need to keep in mind that nitrate administration could be a treatment option even in patients with cardiogenic shock.

Endomyocardial fibrosis: missing tricuspid valve and Fontan-like circulation.

Endomyocardial fibrosis (EMF) is a progressive type of obliterative/restrictive cardiomyopathy characterized by fibrosis of the apical endomyocardium of the ventricles. Although the prognosis of EMF patients is poor in tropical regions, the exact clinical course and pathogenesis of patients with EMF are not known. Here, we report the rare case with EMF in the seventh decade, who showed the disappearance of papillary muscles, chordae tendineae, and part of the tricuspid valves due to massive right ventricular thrombus. Because of those unusual findings of the isolated RV involvement, we observed continuous forward pulmonary artery flow, as occurring in a Fontan circulation.

Optimal conditions for cardiac catheter ablation using photodynamic therapy.

AIMS: Photodynamic therapy (PDT) is based on non-thermal injury mediated by singlet oxygen species and is used clinically in cancer therapy. In our continuing efforts to apply this technology to cardiac catheter ablation, we clarified the optimal condition for creating PDT-mediated lesions using a laser catheter. METHODS AND RESULTS: In a total of 35 canines, we applied a laser directly to the epicardium of the beating heart during open-chest surgery at 15 min after administration of a photosensitizer, talaporfin sodium. We evaluated the lesion size (depth and width) using hematoxylin-eosin staining under varying conditions as follows: laser output (5, 10, 20 W/cm(2)), irradiation time (0-60 s), photosensitizer concentration (0, 2.5, 5 mg/kg), blood oxygen concentration (103.5 ± 2.1 vs. 548.0 ± 18.4 torr), and contact force applied during irradiations (low: <20 g, high: >20 g). A laser irradiation at 20 W/cm(2) for 60 s under 5 mg/kg (29 µg/mL) of photosensitizer induced a lesion 8.7 ± 0.8 mm deep and 5.2 ± 0.2 mm wide. The lesion size was thus positively correlated to the laser power, irradiation time, and photosensitizer concentration, and was independent of the applied contact force and oxygen concentration. In addition, the concentration of the photosensitizer strongly correlated with the changes in the pulse oximetry data and fluorescence of the backscattering laser, suggesting that a clinically appropriate condition could be estimated in real time. CONCLUSION: Photodynamic therapy-mediated cardiac lesions might be controllable by regulating the photosensitizer concentration, laser output, and irradiation time.

Visualization of the left atrial appendage by phased-array intracardiac echocardiography from the pulmonary artery in patients with atrial fibrillation.

AIMS: The left atrial appendage (LAA) represents the major source of cardiac thrombus formation in patients with atrial fibrillation (AF). Phased-array intracardiac echocardiography (ICE) has become available and frequently used during catheter ablation of AF. We attempted to study the feasibility of using ICE for the visualization and evaluation of the LAA from the pulmonary artery (PA) in patients with AF. METHODS AND RESULTS: Eighty patients with AF undergoing catheter ablation (70 males, 57.5 ± 9.1 years) were included. Transoesophageal echocardiography was performed on the prior day before the catheter ablation, and ICE was performed just before the transseptal puncture during the catheter ablation. The ICE catheter was advanced up into the PA from the femoral vein, where the LAA was clearly and entirely visualized by manipulating the ICE catheter. We compared the degree of spontaneous echo contrast, and the correlation was obtained between the ICE and TEE (κ = 0.534, P < 0.001). Furthermore, the LAA flow velocity (LAA emptying and filling velocities) measured by ICE had a good correlation to that measured by TEE (R = 0.872, P < 0.01 and R = 0.753, P < 0.01, respectively). No patients developed any complications. CONCLUSION: The utilization of ICE in the PA is feasible for the observation and evaluation of the LAA.

Time-lapse imaging of cell cycle dynamics during development in living cardiomyocyte.

Mammalian cardiomyocytes withdraw from the cell cycle shortly after birth, although it remains unclear how cardiomyocyte cell cycles behave during development. Compared to conventional immunohistochemistry in static observation, time-lapse imaging can reveal comprehensive data in hard-to-understand biological phenomenon. However, there are no reports of an established protocol of successful time-lapse imaging in mammalian heart. Thus, it is valuable to establish a time-lapse imaging system to enable the observation of cell cycle dynamics in living murine cardiomyocytes. This study sought to establish time-lapse imaging of murine heart to study cardiomyocyte cell cycle behavior. The Fucci (fluorescent ubiquitination-based cell cycle indicator) system can effectively label individual G1, S/G2/M, and G1/S-transition phase nuclei red, green and yellow, respectively, in living mammalian cells, and could therefore be useful to visualize the real-time cell cycle transitions in living murine heart. To establish a similar system for time-lapse imaging of murine heart, we first developed an ex vivo culture system, with the culture conditions determined in terms of sample state, serum concentration, and oxygen concentration. The optimal condition (slice culture, oxygen concentration 20%, serum concentration 10%) successfully mimicked physiological cardiomyocyte proliferation in vivo. Time-lapse imaging of cardiac slices from E11.5, E14.5, E18.5, and P1 Fucci-expressing transgenic mice revealed an elongated S/G2/M phase in cardiomyocytes during development. Our time-lapse imaging of murine heart revealed a gradual elongation of the S/G2/M phase during development in living cardiomyocytes.

Serum inflammation markers predicting successful initial catheter ablation for atrial fibrillation.

BACKGROUND: We investigated various serum inflammatory markers to predict ablation responders who have no atrial fibrillation (AF) relapse after the initial ablation. METHODS: Forty-four consecutive AF patients (age: 59 ± 8 years, paroxysmal: 31, CHADS2: 1.1 ± 1.1) who underwent an initial pulmonary vein isolation were investigated. Various serum inflammatory markers, such as adiponectin, ANP, BNP, 1CTP, F1+2, hs-CRP, IL-6, intact P1NP, MDA-LDL, MMP-2, TGF-ß, TIMP-2, and TNF-α, were evaluated prior to ablation. AF relapse was defined as AF documented in telemonitoring electrocardiograms twice a day during 9.7 ± 2.4 months of follow-up with three months of a blanking-period. RESULTS: A total of 29 patients (paroxysmal: 21) maintained sinus rhythm after the initial catheter ablation. These ablation responders had significantly lower MMP-2 (Sinus vs. Relapsed: 748 ± 132.7 vs. 841.2 ± 152.4 ng/mL, P=0.042) and TNF-α (1.1 ± 0.4 vs. 1.8 ± 1.7 pg/mL, P=0.046) levels prior to ablation. A BNP-adjusted Cox multivariate regression analysis revealed that the independent predictive factor for AF recurrence was high MMP-2 levels (>766 ng/mL) accompanied by high TNF-α levels (>1.2 pg/mL). CONCLUSIONS: The levels of MMP-2 and TNF-α might be useful for predicting initial AF catheter ablation responders.

Assessment of patient characteristics influencing the complexity of leadless pacemaker implantation.

Background: The complexity of leadless pacemaker (LP) implantation varies widely. However, the predictive factors determining this difficulty are poorly understood. Objective: The purpose of this study was to evaluate the factors influencing LP implantation difficulty, specifically procedural time during right atrial (RA) and right ventricular (RV) manipulation, based on patient background, cardiac function, and anatomic characteristics. Methods: Analysis included LP implantation cases between 2017 and 2023, excluding the initial 3 implants performed by each operator. The relevance of patient background, cardiac function, and anatomic features on procedural and fluoroscopy times was evaluated. Results: Fifty-four patients (mean age 82.2 ± 10.0 years; 57.4% male) were included in the study. Median procedural and fluoroscopy time was 45.8 minutes and 16.0 minutes, respectively, with an average of 2.0 ± 1.4 device deployments. Univariate analysis showed associations between procedural time and older age, RA and RV diameter, and severity of tricuspid regurgitation (TR). After adjustment for physician and potential contributing factors, RV dilation (midventricular diameter ≥35 mm) and severe TR were identified as independent predictors of prolonged procedural time. Medical history exhibited no association with procedural time. Consistent results were observed in analyses using fluoroscopy time as the outcome. Conclusion: RV dilation and severe TR were associated with prolonged procedural time for LP implantation. Anatomic features obtained from preprocedural echocardiography could provide valuable insights into both the safety and efficiency of LP implantation, thereby enhancing tailored treatment strategies for patients undergoing pacemaker implantation.