Gene-Based Risk Stratification for Cardiac Disorders in LMNA Mutation Carriers.

BACKGROUND: Mutations in LMNA (lamin A/C), which encodes lamin A and C, typically cause age-dependent cardiac phenotypes, including dilated cardiomyopathy, cardiac conduction disturbance, atrial fibrillation, and malignant ventricular arrhythmias. Although the type of LMNA mutations have been reported to be associated with susceptibility to malignant ventricular arrhythmias, the gene-based risk stratification for cardiac complications remains unexplored. METHODS AND RESULTS: The multicenter cohort included 77 LMNA mutation carriers from 45 families; cardiac disorders were retrospectively analyzed. The mean age of patients when they underwent genetic testing was 45±17, and they were followed for a median 49 months. Of the 77 carriers, 71 (92%) were phenotypically affected and showed cardiac conduction disturbance (81%), low left ventricular ejection fraction (<50%; 45%), atrial arrhythmias (58%), and malignant ventricular arrhythmias (26%). During the follow-up period, 9 (12%) died, either from end-stage heart failure (n=7) or suddenly (n=2). Genetic analysis showed truncation mutations in 58 patients from 31 families and missense mutations in 19 patients from 14 families. The onset of cardiac disorders indicated that subjects with truncation mutations had an earlier occurrence of cardiac conduction disturbance and low left ventricular ejection fraction, than those with missense mutations. In addition, the truncation mutation was found to be a risk factor for the early onset of cardiac conduction disturbance and the occurrence of atrial arrhythmias and low left ventricular ejection fraction, as estimated using multivariable analyses. CONCLUSIONS: The truncation mutations were associated with manifestation of cardiac phenotypes in LMNA-related cardiomyopathy, suggesting that genetic analysis might be useful for diagnosis and risk stratification.

Patient-Specific Human Induced Pluripotent Stem Cell Model Assessed with Electrical Pacing Validates S107 as a Potential Therapeutic Agent for Catecholaminergic Polymorphic Ventricular Tachycardia.

INTRODUCTION: Human induced pluripotent stem cells (hiPSCs) offer a unique opportunity for disease modeling. However, it is not invariably successful to recapitulate the disease phenotype because of the immaturity of hiPSC-derived cardiomyocytes (hiPSC-CMs). The purpose of this study was to establish and analyze iPSC-based model of catecholaminergic polymorphic ventricular tachycardia (CPVT), which is characterized by adrenergically mediated lethal arrhythmias, more precisely using electrical pacing that could promote the development of new pharmacotherapies. METHOD AND RESULTS: We generated hiPSCs from a 37-year-old CPVT patient and differentiated them into cardiomyocytes. Under spontaneous beating conditions, no significant difference was found in the timing irregularity of spontaneous Ca2+ transients between control- and CPVT-hiPSC-CMs. Using Ca2+ imaging at 1 Hz electrical field stimulation, isoproterenol induced an abnormal diastolic Ca2+ increase more frequently in CPVT- than in control-hiPSC-CMs (control 12% vs. CPVT 43%, p<0.05). Action potential recordings of spontaneous beating hiPSC-CMs revealed no significant difference in the frequency of delayed afterdepolarizations (DADs) between control and CPVT cells. After isoproterenol application with pacing at 1 Hz, 87.5% of CPVT-hiPSC-CMs developed DADs, compared to 30% of control-hiPSC-CMs (p<0.05). Pre-incubation with 10 µM S107, which stabilizes the closed state of the ryanodine receptor 2, significantly decreased the percentage of CPVT-hiPSC-CMs presenting DADs to 25% (p<0.05). CONCLUSIONS: We recapitulated the electrophysiological features of CPVT-derived hiPSC-CMs using electrical pacing. The development of DADs in the presence of isoproterenol was significantly suppressed by S107. Our model provides a promising platform to study disease mechanisms and screen drugs.

Cardiac sodium channel mutation associated with epinephrine-induced QT prolongation and sinus node dysfunction.

BACKGROUND: Long-QT syndrome (LQTS) is an inherited arrhythmia characterized by prolonged ventricular repolarization and malignant tachyarrhythmias. LQT1, LQT2, and LQT3 are caused by mutations in KCNQ1 (LQT1), KCNH2 (LQT2), and SCN5A (LQT3), which account for approximately 90% of genotyped LQTS patients. Most cardiac events in LQT1 patients occur during exercise, whereas patients with LQT3 tend to have arrhythmic events during rest or asleep. OBJECTIVE: The study aimed to identify a genetic mutation in a Japanese man who presented with sinus node dysfunction and prolonged QT interval on exercise and epinephrine stress tests, as well as to clarify the electrophysiological properties of mutant channels. METHODS: LQTS-related genes were screened in this patient. Electrophysiological functional assays were conducted with a heterologous expression system. RESULTS: We identified a heterozygous missense SCN5A mutation, V2016M, which changes the last amino acid of the cardiac sodium channel. Electrophysiological analyses revealed that the mutant channels exhibited a loss-of-function feature, decreased peak sodium current densities (wild type 175.2 ± 17.6 pA/pF; V2016M 97.2 ± 16.0 pA/pF; P < .01). In addition, the mutant channels showed gain-of-function features: increased late sodium currents by protein kinase A activation (wild type 0.07 ± 0.01%; V2016M 0.17 ± 0.03%; P < .05) and impaired inactivation of sodium channels by protein kinase A or C activation. CONCLUSION: We identified an SCN5A mutation in a patient with sinus node dysfunction and epinephrine-induced QT prolongation, which was an atypical phenotype for LQT3. The electrophysiological properties of the mutant channels might be associated with the overlapping clinical features of the patient.

Incidence and outcome of surgical procedures after coronary artery bypass grafting compared with those after percutaneous coronary intervention: a report from the Coronary Revascularization Demonstrating Outcome Study in Kyoto PCI/CABG Registry Cohort-2.

BACKGROUND: Noncardiac surgery after percutaneous coronary intervention (PCI) has been reported to be carrying high risk for both ischemic and bleeding complications. However, there has been no report comparing the incidence and outcomes of surgical procedures after coronary artery bypass grafting (CABG) with those after PCI. METHODS AND RESULTS: Among 14 383 patients undergoing first coronary revascularization (PCI, n=12 207; CABG, n=2176) enrolled in the Coronary Revascularization Demonstrating Outcome Study in Kyoto (CREDO-Kyoto) PCI/CABG Registry Cohort-2, surgical procedures were performed more frequently after CABG (n=560) than after PCI (n=2398; cumulative 3-year incidence: 27% versus 22%; unadjusted P<0.0001), particularly <6 months of coronary revascularization. The risk for the primary ischemic outcome measure (death/myocardial infarction) at 30-day postsurgical procedures was not significantly different between the CABG and PCI groups (cumulative incidence: 3.1% versus 3.2%; unadjusted P=0.9; adjusted hazard ratio, 0.97; 95% confidence interval, 0.47-1.89; P=0.9). The risk for the primary bleeding outcome measure (moderate or severe bleeding by Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries classification) was lower in the CABG groups than in the PCI group (cumulative incidence: 1.3% versus 2.6%; unadjusted P=0.07; adjusted hazard ratio, 0.36; 95% confidence interval, 0.12-0.87; P=0.02). There were no interactions between the timing of surgery and the types of coronary revascularization (CABG/PCI) for both ischemic and bleeding outcomes. CONCLUSIONS: Surgical procedures were performed significantly more frequently after CABG than after PCI, particularly <6 months after coronary revascularization. Surgical procedures after CABG as compared with those after PCI were associated with similar risk for ischemic events and lower risk for bleeding events, regardless of the timing after coronary revascularization.

Optimal observation time after completion of circumferential pulmonary vein isolation for atrial fibrillation to prevent chronic pulmonary vein reconnections.

PURPOSE: To identify predictors of chronic pulmonary vein (PV) reconnection (CPVR) after successful circumferential PV isolation (CPVI) for atrial fibrillation (AF). MATERIALS AND METHODS: A total of 718 PVs from 181 consecutive AF patients (141 males, median age 61 years, 92 paroxysmal AF) who underwent a second ablation procedure for recurrent AF were retrospectively analyzed. RESULTS: During the second procedure, a CPVR was observed in 477 PVs (66.4%) among 169 patients. In a multiple logistic regression analysis, the observation time after the final completion of the PVI (OT-final) was a significant negative predictor (odds ratio 0.980; P<0.001). A receiver operating characteristic analysis demonstrated that the greatest area under the curve was for the OT-final (0.670). At an optimal cutoff of 35 min, the sensitivity and specificity for predicting a CPVR were 66.9% and 60.6%, respectively. By Kaplan Meier analysis, CPVR was more frequent in PVs with an OT-final of <35 min than ≥35 min (log-rank test, P=0.018). In a vessel-by-vessel analysis, the OT-final at all PV sites was a significant negative predictor, while male gender in the right PVs and left-inferior PV, number of RF applications for the ipsilateral CPVI in the right PVs and left-superior PV, and major PV diameter in the left-superior PV were significant positive predictors of a CPVR (all P<0.05). CONCLUSIONS: An optimal observation time (≥35 min in this study) to determine whether PVI is successfully completed during the initial CPVI for AF may be needed to prevent a CPVR and subsequent AF recurrence thereafter.

Influence of initial acute myocardial infarction presentation on the outcome of surgical procedures after coronary stent implantation: a report from the CREDO-Kyoto PCI/CABG Registry Cohort-2.

Several previous publications have consistently reported that surgical procedures performed early after coronary stenting were associated with significantly higher risk for ischemic events than those performed late. In the current post hoc analysis of the Coronary REvascularization Demonstrating Outcome Study in Kyoto PCI/coronary artery bypass grafting Registry Cohort-2, we compared the outcomes of early (within 42 days) versus late surgery (beyond 42 days) after coronary stenting stratified by the initial clinical presentations [acute myocardial infarction (AMI) [early N = 153, and late N = 586] and non-AMI (early N = 202, and late N = 1457)]. Cumulative incidence of death/myocardial infarction/stent thrombosis at 30 days after surgery was significantly higher in the early group than in the late group in the AMI stratum [18.4 vs. 2.6 %, P < 0.0001, and adjusted HR 5.65 (95 % CI 2.42-13.5), P < 0.0001], but not in the non-AMI stratum [3.0 vs. 1.8 %, P = 0.3, and adjusted HR 1.52 (95 % CI 0.47-4.17), P = 0.5]. There was a significant interaction for the risk of ischemic events between the clinical presentation and the timing of surgery (P interaction = 0.03). Deaths in patients with early surgery in the AMI stratum were mostly related to preoperative complications of AMI (76 %), but not related to perioperative stent-related complications (4.0 %). In conclusion, significantly higher risk of early versus late surgery for perioperative ischemic events was seen only in patients with initial AMI presentation, but not in patients with non-AMI presentation. Previous observations suggesting higher risk in early surgery might not be related to the timing after stent implantation per se, but related to more morbid preoperative conditions in patients who underwent early surgery.

Comparison of long-term outcome after percutaneous coronary intervention versus coronary artery bypass grafting in patients with unprotected left main coronary artery disease (from the CREDO-Kyoto PCI/CABG Registry Cohort-2).

The long-term outcome of percutaneous coronary intervention (PCI) compared to coronary artery bypass grafting (CABG) for unprotected left main coronary artery disease (ULMCAD) remains to be investigated. We identified 1,005 patients with ULMCAD of 15,939 patients with first coronary revascularization enrolled in the CREDO-Kyoto PCI/CABG Registry Cohort-2. Cumulative 3-year incidence of a composite of death/myocardial infarction (MI)/stroke was significantly higher in the PCI group than in the CABG group (22.7% vs 14.8%, p = 0.0006, log-rank test). However, the adjusted outcome was not different between the PCI and CABG groups (hazard ratio [HR] 1.30, 95% confidence interval [CI] 0.79 to 2.15, p = 0.30). Stratified analysis using the SYNTAX score demonstrated that risk for a composite of death/MI/stroke was not different between the 2 treatment groups in patients with low (<23) and intermediate (23 to 33) SYNTAX scores (adjusted HR 1.70, 95% CI 0.77 to 3.76, p = 0.19; adjusted HR 0.86, 95% CI 0.37 to 1.99, p = 0.72, respectively), whereas in patients with a high SYNTAX score (≥33), it was significantly higher after PCI than after CABG (adjusted HR 2.61, 95% CI 1.32 to 5.16, p = 0.006). In conclusion, risk of PCI for serious adverse events seemed to be comparable to that after CABG in patients with ULMCAD with a low or intermediate SYNTAX score, whereas PCI compared with CABG was associated with a higher risk for serious adverse events in patients with a high SYNTAX score.

Incidence and outcome of surgical procedures after coronary bare-metal and drug-eluting stent implantation: a report from the CREDO-Kyoto PCI/CABG registry cohort-2.

BACKGROUND: There still remain safety concerns on surgical procedures after coronary drug-eluting stents (DES) implantation, and optimal management of perioperative antiplatelet therapy (APT) has not been yet established. METHODS AND RESULTS: During 3-year follow-up of 12 207 patients (DES=6802 patients and bare-metal stent [BMS] only=5405 patients) who underwent coronary stent implantation in the CREDO-Kyoto registry cohort-2, surgical procedures were performed in 2398 patients (DES=1295 patients and BMS=1103 patients). Surgical procedures (early surgery in particular) were more frequently performed in the BMS group than in the DES group (4.4% versus 1.9% at 42-day and 23% versus 21% at 3-year, log-rank P=0.0007). Cumulative incidences of death/myocardial infarction (MI)/stent thrombosis (ST) and bleeding at 30 days after surgery were low, without differences between BMS and DES (3.5% versus 2.9%, P=0.4 and 3.2% versus 2.1%, P=0.2, respectively). The adjusted risks of DES use relative to BMS use for death/MI/ST and bleeding were not significant (hazard ratio: 1.63, 95% confidence interval: 0.93 to 2.87, P=0.09 and hazard ratio: 0.6, 95% confidence interval: 0.34 to 1.06, P=0.08, respectively). The risks of perioperative single- and no-APT relative to dual-APT for both death/MI/ST and bleeding were not significant; single-APT as compared with dual-APT tended to be associated with lower risk for death/MI/ST (hazard ratio: 0.4, 95% confidence interval: 0.13 to 1.01, P=0.053). CONCLUSIONS: Surgical procedures were commonly performed after coronary stent implantation, and the risk of ischemic and bleeding complications in surgical procedures was low. In patients selected to receive DES or BMS, there were no differences in outcomes. Perioperative administration of dual-APT was not associated with lower risk for ischemic events.