Clinical Outcomes of Myocardial Bridging versus No Myocardial Bridging in Patients with Apical Hypertrophic Cardiomyopathy.

OBJECTIVE: To determine the prevalence and clinical effects of myocardial bridging (MB) in patients with apical hypertrophic cardiomyopathy (AHCM). METHODS: Angiograms from 212 AHCM patients were reviewed to identify MB. The patients were classified into 2 groups: AHCM with and AHCM without MB. We reviewed patient records on cardiovascular (CV) risk factors, symptoms, CV events, and CV mortality. RESULTS: In all, 60 patients with MB and 100 without MB were included. Rates of angina (61.7 vs. 40%; p = 0.008), mimicking non-ST-segment elevation myocardial infarction (15 vs. 3%, p = 0.013), and Canadian Cardiovascular Society class III/IV angina (18.3 vs. 4%; p = 0.003) were higher in patients with MB than in those without. Mean follow-up periods (65.5 ± 50.5 vs. 64.4 ± 43.6 months, p = 0.378) and CV mortality (3.3 vs. 1%; p = 0.652) were similar in the 2 groups. Kaplan-Meier estimates demonstrated that CV event-free survival rates were lower in patients with MB than in those without (71.7 vs. 88%; p = 0.022). MB, late gadolinium enhancement, and female sex were independent risk factors for CV events in a multivariate Cox regression analysis adjusted for other risk factors. CONCLUSION: More serious symptoms and a higher risk of CV events were observed in AHCM patients with MB than in those without MB. CV mortality was similar in these 2 groups.

Incidence of ischemic stroke and systemic embolism in patients with hypertrophic cardiomyopathy, nonvalvular atrial fibrillation, CHA2DS2-VASc score of ≤1 and without anticoagulant therapy.

Data on the risk of ischemic stroke and systemic embolism (iSSE) events in patients with nonvalvular atrial fibrillation (NVAF), a CHA2DS2-VASc score of ≤1, hypertrophic cardiomyopathy (HCM), and without anticoagulant therapy are still lacking. The aim of this study was to investigate the incidence of iSSE events in these patients. We consecutively screened medical records of patients with HCM and NVAF referred to Fuwai Hospital between January 1994 and March 2014. The primary end point was iSSE events, defined as a composite of ischemic stroke and systemic embolism. Follow-up was carried out to ascertain end point status. Medical records of 522 patients with NVAF and HCM were screened. A total of 108 patients (20.7 %) with a CHA2DS2-VASc score of ≤1 and without anticoagulant therapy were enrolled and constituted our study population. After a median follow-up of 2.4 years (range 0.6-14.1 years; 376.2 patient-years), ischemic stroke occurred in 2 patients, resulting in death of 1 patient in the first year and paralysis of the other patient in the fourth year. No other iSSE events occurred. The incidence of iSSE was 0.9 % [95 % confidence interval (CI) 0.0-5.0 %] in the first year, and 0.5 % per 100 patient-years (95 % CI 0.1-1.9 %). The risk of iSSE events seems low in patients with NVAF, a CHA2DS2-VASc score of ≤1, HCM, and without anticoagulant therapy. Multicenter studies with sizeable study populations are needed to validate the risk of iSSE events in these patients.

Structural basis for calcium and magnesium regulation of a large conductance calcium-activated potassium channel with ß1 subunits.

Large conductance Ca(2+)- and voltage-activated potassium (BK) channels, composed of pore-forming α subunits and auxiliary ß subunits, play important roles in diverse physiological activities. The ß1 is predominately expressed in smooth muscle cells, where it greatly enhances the Ca(2+) sensitivity of BK channels for proper regulation of smooth muscle tone. However, the structural basis underlying dynamic interaction between BK mSlo1 α and ß1 remains elusive. Using macroscopic ionic current recordings in various Ca(2+) and Mg(2+) concentrations, we identified two binding sites on the cytosolic N terminus of ß1, namely the electrostatic enhancing site (mSlo1(K392,R393)-ß1(E13,T14)), increasing the calcium sensitivity of BK channels, and the hydrophobic site (mSlo1(L906,L908)-ß1(L5,V6,M7)), passing the physical force from the Ca(2+) bowl onto the enhancing site and S6 C-linker. Dynamic binding of these sites affects the interaction between the cytosolic domain and voltage-sensing domain, leading to the reduction of Mg(2+) sensitivity. A comprehensive structural model of the BK(mSlo1 α-ß1) complex was reconstructed based on these functional studies, which provides structural and mechanistic insights for understanding BK gating.

Microfluidic-Based Holonomic Constraints of siRNA in the Kernel of Lipid/Polymer Hybrid Nanoassemblies for Improving Stable and Safe In Vivo Delivery.

A safe and efficient delivery system is critical for clinical application of siRNA. However, the conventional electrostatic interaction-based siRNA nanoplexes with bulk mixing preparation were always unsatisfactory for its stability and safety. In this study, the new core-shell lipid/PCL-PEI/siRNA nanoparticles (LPS NPs) endowing holonomic constraint of siRNA in the inner core were prepared by microfluidic technology. On the microfluidic chip, siRNAs were completely compressed into the inner hydrophilic core of reverse PCL-PEI micelles at a low N/P ratio of 5, followed by coating a neutral lipid membrane to form core-shell nanoparticles, which had a uniform size (120.2 ± 1.4 nm) and a negative charge (-8.8 ± 1.6 mV). Compared to bulk mixing-based LMS NPs, the lower usage of cationic PCL-PEI materials and stronger protection of siRNA in serum were found in the microfluidic-based LPS NPs. Furthermore, it was demonstrated that the LPS NPs exhibited significant downregulation of EGFR mRNA and protein expression level both in vitro and in vivo, and showed significant inhibition of tumor growth following systemic administration along with no obvious systemic toxicity. These findings demonstrated that the microfluidic-based lipid/polymer hybrid nanoassemblies would offer a promising siRNA delivery system for clinical application.

Long-term survival after acute myocardial infarction in patients with hypertrophic cardiomyopathy.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is associated with poor prognosis. It has been reported that there is no difference in in-hospital mortality after acute myocardial infarction (AMI) between patients with and without HCM. However, whether there is a difference in long-term survival after AMI between patients with and without HCM remains unclear. HYPOTHESIS: Long-term survival after AMI is worse in patients with vs without HCM. METHODS: The clinical profiles of 91 consecutive patients with HCM and AMI (HCM group) and 91 sex- and age-matched patients with AMI without HCM (non-HCM group) were analyzed. The study endpoint was all-cause mortality. RESULTS: During a follow-up period of 4.9 ± 3.6 years, all-cause mortality occurred in 25 patients (27.5%) in the HCM group and 13 patients (14.3%) in the non-HCM group. The survival of the HCM group was inferior to that of the non-HCM group (log-rank P = 0.039). During the first year of follow-up, 3 deaths (3.3%) occurred in the HCM group and 7 deaths (7.7%) occurred in the non-HCM group (log-rank P = 0.177). Among patients who survived beyond the first year of follow-up (172 patients), the annual mortality rates were 6.3% (95% confidence interval: 4.0%-9.3%) in the HCM group and 1.6% (95% confidence interval: 0.6%-3.5%) in the non-HCM group (log-rank P = 0.001). CONCLUSIONS: AMI patients with HCM exhibited worse long-term survival than did AMI patients without HCM.

Brain tumor-targeted therapy by systemic delivery of siRNA with Transferrin receptor-mediated core-shell nanoparticles.

Treatment of brain tumor remains a great challenge worldwide. Development of a stable, safe, and effective siRNA delivery system which is able to cross the impermeable blood-brain barrier (BBB) and target glioma cells is necessary. This study aims to investigate the therapeutic effects of intravenous administration of T7 peptide modified core-shell nanoparticles (named T7-LPC/siRNA NPs) on brain tumors. Layer-by-layer assembling of protamine/chondroitin sulfate/siRNA/cationic liposomes followed by T7 peptide modification has been carried out in order to obtain a targeted siRNA delivery system. In vitro cellular uptake experiments demonstrated a higher intracellular fluorescence intensity of siRNA in brain microvascular endothelial cells (BMVECs) and U87 glioma cells when treated with T7-LPC/siRNA NPs compared with PEG-LPC/siRNA NPs. In the co-culture model of BMVECs and U87 cells, a significant down-regulation of EGFR protein expression occurred in the U87 glioma cells after treatment with the T7-LPC/siEGFR NPs. Moreover, the T7-LPC/siRNA NPs had an advantage in penetrating into a deep region of the tumor spheroid compared with PEG-LPC/siRNA NPs. In vivo imaging revealed that T7-LPC/siRNA NPs accumulated more specifically in brain tumor tissues than the non-targeted NPs. Also, in vivo tumor therapy experiments demonstrated that the longest survival period along with the greatest downregulation of EGFR expression in tumor tissues was observed in mice with an intracranial U87 glioma treated with T7-LPC/siEGFR NPs compared with mice receiving other formulations. Therefore, we believe that these transferrin receptor-mediated core-shell nanoparticles are an important potential siRNA delivery system for brain tumor-targeted therapy.

Effectiveness of Alcohol Septal Ablation in Obstructive Hypertrophic Cardiomyopathy With Versus Without Extreme Septal Hypertrophy.

AIMS: Data on the effectiveness of alcohol septal ablation (ASA) in patients with hypertrophic cardiomyopathy (HCM) and extreme septal hypertrophy (ESH) are lacking. This study aimed to compare the effectiveness of ASA in patients with vs without ESH. METHODS: Clinical profiles of 17 patients with ESH and 256 patients without ESH were compared. RESULTS: Baseline pressure gradient and limiting symptoms were comparable between patients with and without ESH. At median 1.1 years of follow-up after ASA, pressure gradient was 48.5 ± 40.4 mm Hg in the ESH group and 40.9 ± 35.2 mm Hg in the non-ESH (N-ESH) group (P=.33). Patients with New York Heart Association class III/IV represented 5.9% of the ESH group and 16.9% of the N-ESH group (P=.39). Patients with Canadian Cardiovascular Society class III/IV represented 5.9% of the ESH group and 10.2% of the N-ESH group (P=.87). CONCLUSION: The effectiveness of ASA seems comparable between patients with and without ESH.

Systemic delivery of siRNA by T7 peptide modified core-shell nanoparticles for targeted therapy of breast cancer.

Systemic delivery of siRNA is the most challenging step to transfer RNAi to clinical application for breast cancer therapy. In this study, the tumor targeted, T7 peptide modified core-shell nanoparticles (named as T7-LPC/siRNA NPs) were constructed to achieve effective systemic delivery of siRNA. The core-shell structure of T7-LPC/siRNA NPs enables them to encapsulate siRNA in the core and protect it from RNase degradation during circulation. In vitro cellular uptake and gene silencing experiments demonstrated that T7-LPC/siEGFR NPs could deliver EGFR siRNA into breast cancer cells through receptor mediated endocytosis and effectively down-regulate the EGFR expression. In vivo distribution study proved the T7-LPC/siRNA NPs could deliver fluorescence labeled siRNA to the tumor site more efficiently than the non-targeted PEG-LPC/siRNA NPs after intravenous administration. Furthermore, the experiments of in vivo tumor therapy confirmed that intravenous administration of T7-LPC/siEGFR NPs led to an effective EGFR down-regulation and an obvious inhibition of breast tumor growth, with little activation of immune responses and negligible body weight loss. These results suggested that T7-LPC/siRNA NPs could be an effective and safe systemic siRNA delivery system for RNAi-based breast cancer therapy.

Survival after alcohol septal ablation versus conservative therapy in obstructive hypertrophic cardiomyopathy.

BACKGROUND: The impact of alcohol septal ablation (ASA) on the survival of patients with drug-refractory obstructive hypertrophic cardiomyopathy (HCM) remains unresolved. The aim of this study was to compare survival after ASA vs. conservative therapy. METHODS: We studied a consecutive cohort of 274 patients with severe drug-refractory obstructive HCM, 229 in ASA group and 45 in conservative group. The primary endpoint was a composite of all-cause mortality and aborted cardiac arrest. RESULTS: With a median follow-up of 4.3 years, primary endpoint occurred in 13 (5.7%) patients in the ASA group, and 8 (17.8%) patients in the conservative group. The 5- and 10-year survival free from primary endpoint of the ASA group (94.5% and 93.0%, respectively) was significantly better than that of the conservative group (78.3% and 72.2%, respectively, log-rank p = 0.009). Independent determinants of primary endpoint were ASA therapy (hazard ratio [HR] 0.22; 95% confidence interval [CI] 0.08-0.60; p = 0.003) and maximal septal thickness (HR 1.14; 95% CI 1.03-1.27; p = 0.011). CONCLUSIONS: In patients with severe drug-refractory obstructive HCM, survival after ASA is favorable and better than that of conservative therapy. ASA seems to improve survival.

Clinical characteristics and prognosis of 60 patients with midventricular obstructive hypertrophic cardiomyopathy.

BACKGROUND: Midventricular obstructive hypertrophic cardiomyopathy (MVOHCM) is a rare form of hypertrophic cardiomyopathy. Knowledge regarding the diagnosis, morbidity and cardiovascular mortality is limited. In this study, we aimed to describe the long-term outcomes of patients with MVOHCM followed in a tertiary referral centre.Methods A retrospective study of 60 patients with MVOHCM diagnosed at FuWai Hospital was performed. Clinical features, mortality and cardiovascular morbidity were analysed. RESULTS: The 60 patients with MVOHCM represented 2.9% of all the hypertrophic cardiomyopathy cases (n = 2068). At diagnosis, the mean age was 40.2 ±â€Š15.0 years. During 7.1 ±â€Š6.3 years of follow-up after diagnosis, the cardiovascular mortality was 15.0%. The probability of survival at 10 years was 77.0 ±â€Š8.0%. The following two predictors of cardiovascular mortality were identified: severe ventricular septal hypertrophy at least 30  mm (hazard ratio, 3.19; P = 0.031) and unexplained syncope (hazard ratio, 4.59; P = 0.002) at baseline. Thirty patients (50.0%) had one or more morbid events, and the most frequent was nonsustained ventricular tachycardia. Apical aneurysm formation was identified in 20% of patients, and the patients with apical aneurysms were more inclined to experience nonsustained ventricular tachycardia than patients without apical aneurysm (58.3 vs. 16.7%; P = 0.003). Peak pressure gradient at least 70  mm Hg (hazard ratio, 3.00; P = 0.01) at baseline was identified as the only predictor of apical aneurysm. CONCLUSION: In Chinese patients, MVOHCM is associated with an unfavourable prognosis of cardiovascular mortality. One-half of these patients experience major cardiovascular events, and 20% develop an apical aneurysm, which significantly increases arrhythmia events. These data warrant measures to ensure the early recognition of MVOHCM followed by appropriate therapeutic interventions.

Comparison of the prevalence, clinical features, and long-term outcomes of midventricular hypertrophy vs apical phenotype in patients with hypertrophic cardiomyopathy.

BACKGROUND: Previous studies on the association between the distribution of left ventricle hypertrophy and the clinical features of hypertrophic cardiomyopathy (HCM) have yielded unclear results. The aim of this study was to investigate the differences in the prevalence, clinical features, management strategies, and long-term outcomes between patients with midventricular hypertrophic obstructive cardiomyopathy (MVHOCM) and patients with apical HCM (ApHCM). METHODS: A retrospective study of 60 patients with MVHOCM and 263 patients with ApHCM identified in a consecutive single-centre cohort consisting of 2068 patients with HCM was performed. The prevalence, clinical features, and natural history of the patients in these 2 groups were compared. RESULTS: Compared with ApHCM patients, patients with MVHOCM tended to be much younger and more symptomatic during their initial evaluation. Over a mean follow-up of 7 years, the probability of cardiovascular mortality and that of morbidity was significantly greater in MVHOCM patients compared with ApHCM patients (log-rank, P < 0.001). CONCLUSIONS: Our results suggest that, compared with ApHCM, MVHOCM represents an uncommon presentation of the clinical spectrum of HCM that is characterized by progressive clinical deterioration leading to increased cardiovascular mortality and morbidity. Our results also underscore the importance of the timely recognition of MVHOCM for the prediction of prognosis and the early consideration of appropriate management strategies.