Use of 3D Echocardiography Facilitates Analysis of Thrombolytic Efficacy in Patients With Persistent Atrial Fibrillation.

ABSTRACT: This study seeks to identify the anticoagulant efficacy of rivaroxaban treatment on thrombi detected using echocardiography of the left atrial appendage in 275 patients with persistent atrial fibrillation. During follow-up after 9-24 weeks of rivaroxaban treatment, patients were divided into "effective group" (n = 143) and "ineffective group" (n = 132) according to the thrombolytic effect of the drug. Left atrial diameter (LAD), left atrial ejection fraction (LAEF), left ventricular ejection fraction (LVEF), mean diameter of left atrial appendage (LAAD mean ), angle between left atrial appendage and left atrium (LAA-A), velocity of blood flow in left atrial appendage (LAA-v), and thrombus size were compared before and after drug administration. Following treatment, LAEF, LVEF, and LAA-v values were greater and LAD and LAAD mean values were lower in the effective ( P < 0.05). Logistic regression analysis showed significant correlations of LAD, LAEF, LVEF, LAA-A, and LAA-v with anticoagulant efficacy ( P < 0.05). The efficacy of rivaroxaban in treatment of left atrial auricular thrombosis in patients with persistent AF was correlated with LAD, LAEF, LVEF, LAA-A, and LAA-v. Multivariate logistic regression analysis further revealed LAEF [odds ratio (OR) 1.7, 95% confidence interval (CI), 0.45-16.9, P = 0.008], 3D-EF (OR 6.4, 95% CI, 1.06-16.9, P = 0.039) and left ventricular global longitudinal strain (OR 18.0, 95% CI, 1.38-35.68, P = 0.028) as factors related to left atrial appendage thrombus. Echocardiography with global longitudinal strain assessment could be effectively utilized to evaluate the functional parameters of LAA and thus aid in predicting the safety of rivaroxaban as an anticoagulation agent.

Enhanced CaMKII-Dependent Late INa Induces Atrial Proarrhythmic Activity in Patients With Sleep-Disordered Breathing.

RATIONALE: Sleep-disordered breathing (SDB) is frequently associated with atrial arrhythmias. Increased CaMKII (Ca/calmodulin-dependent protein kinase II) activity has been previously implicated in atrial arrhythmogenesis. OBJECTIVE: We hypothesized that CaMKII-dependent dysregulation of Na current (INa) may contribute to atrial proarrhythmic activity in patients with SDB. METHODS AND RESULTS: We prospectively enrolled 113 patients undergoing elective coronary artery bypass grafting for cross-sectional study and collected right atrial appendage biopsies. The presence of SDB (defined as apnea-hypopnea index ≥15/h) was assessed with a portable SDB monitor the night before surgery. Compared with 56 patients without SDB, patients with SDB (57) showed a significantly increased level of activated CaMKII. Patch clamp was used to measure INa. There was a significantly enhanced late INa, but reduced peak INa due to enhanced steady-state inactivation in atrial myocytes of patients with SDB consistent with significantly increased CaMKII-dependent cardiac Na channel phosphorylation (NaV1.5, at serine 571, Western blotting). These gating changes could be fully reversed by acute CaMKII inhibition (AIP [autocamtide-2 related inhibitory peptide]). As a consequence, we observed significantly more cellular afterdepolarizations and more severe premature atrial contractions in atrial trabeculae of patients with SDB, which could be blocked by either AIP or KN93 (N-[2-[[[(E)-3-(4-chlorophenyl)prop-2-enyl]-methylamino]methyl]phenyl]-N-(2-hydroxyethyl)-4-methoxybenzenesulfonamide). In multivariable linear regression models incorporating age, sex, body mass index, existing atrial fibrillation, existing heart failure, diabetes mellitus, and creatinine levels, apnea-hypopnea index was independently associated with increased CaMKII activity, enhanced late INa and correlated with premature atrial contraction severity. CONCLUSIONS: In atrial myocardium of patients with SDB, increased CaMKII-dependent phosphorylation of NaV1.5 results in dysregulation of INa with proarrhythmic activity that was independent from preexisting comorbidities. Inhibition of CaMKII may be useful for prevention or treatment of arrhythmias in SDB. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT02877745. Visual Overview: An online visual overview is available for this article.

Outcome of non-vitamin K oral anticoagulants in the treatment of left atrial/left atrial appendage thrombus in patients with nonvalvular atrial fibrillation.

BACKGROUND: Data comparing dabigatran with rivaroxaban regarding the resolution of left atrial/left atrial appendage (LA/LAA) thrombus in patients with nonvalvular atrial fibrillation (AF) are scarce. This study aimed to compare the efficacy and safety of dabigatran vs rivaroxaban regarding the resolution of LA/LAA thrombus in patients with nonvalvular AF. METHODS: This retrospective study enrolled nonvalvular AF patients scheduled to undergo catheter ablation or cardioversion in Shanghai Ruijin Hospital between January 2014 and January 2019. Altogether, 34 patients with LA/LAA thrombus detected by transesophageal echocardiography (TEE) were enrolled. Among them, 12 patients were treated with dabigatran 150 mg bid and the other 22 with rivaroxaban 20 mg qd. Follow-up TEE was performed within greater than or equal to 3 weeks to less than 6 months of the initial TEE to evaluate the resolution of the LA/LAA thrombus. RESULTS: Baseline patient characteristics were similar in the two groups. Overall, 18 patients (81.8%) in the rivaroxaban group had complete thrombus resolution after 70.3 ± 22.1 treatment days, and 10 patients (83.3%) in the dabigatran group had complete thrombus resolution after 69.3 ± 47.9 treatment days. There was no significant difference between the groups (P = .6). TEE showed that the average length, width, and area of thrombus significantly decreased in both groups after treatment, although there was no significant difference in the amount of change in these parameters between the two groups after treatment (P = .6). Undissolved thrombus in two patients in the rivaroxaban group did dissolve after switching to dabigatran. CONCLUSIONS: The results suggest that both dabigatran and rivaroxaban are potential options for treating LA/LAA thrombus in patients with nonvalvular AF. Dabigatran could be an alternative option for the resolution of LA/LAA thrombus resistant to rivaroxaban.

Metformin improves lipid metabolism and reverses the Warburg effect in a canine model of chronic atrial fibrillation.

BACKGROUND: Previous studies demonstrated impaired lipid metabolism and augmented aerobic glycolysis in AF. The authors aimed to investigate whether the use of metformin, an AMPK activator, could reverse this metabolic remodeling in chronic AF and to explore the underlying mechanisms. METHODS: We conducted chronic AF animal models with 18 beagle dogs and divided them into SR (pacemaker implanted without pacing), AF (pacemaker implanted with sustained pacing at a frequency of 400 beats/min for 6 weeks), and metformin+AF group (daily oral administration of metformin was initiated 1 week before surgery and continued throughout the study period). After electrophysiological measurements, the left atrial appendage tissue samples were taken from the beating heart for further analysis. Protein expression, histological analysis, and biochemical measurements were conducted. RESULTS: The AF groups showed decreased expression of FAT/CD36, CPT-1, VLCAD, increased concentration of free fatty acid and triglyceride, and increased lipid deposition. The activation of AMPK/PGC-1α/PPARα pathway was decreased. The key factors of the Warburg effect, including HIF-1α, GLUT-1, PDK1, HK, and LDH, increased in AF group compared to SR group. The expression of PDH decreased significantly, accompanied by increased atrial lactate production. The extent of fibrosis increased significantly in the left atrial appendage of AF group. dERP, ∑WOV, and AF inducibility increased while ERP decreased in AF group compared to SR group. The use of metformin attenuated all these changes effectively. CONCLUSIONS: Metformin improves lipid metabolism and reverses the Warburg effect in chronic AF via AMPK activation. It attenuates atrial electrical and structural remodeling.

Management of periprocedural anticoagulant therapy: a novel individualized approach-a transeusophageal echocardiographic study.

Patients with non-valvular atrial fibrillation who are under chronic oral anticoagulant therapy (OAC) treatment frequently require interruption of OAC treatment. By examining the presence of left atrial/left atrial appendage (LA/LAA) thrombus or dense spontaneous echo contrast (SEC) with transesophageal echocardiography (TEE) we aimed to develop an individualized strategy. To test the validity of CHA2DS2VASc score based recommendations was our secondary purpose. In this prospective study patients with non-valvular atrial fibrillation on OAC therapy were included. Patients' baseline characteristics, CHA2DS2VASc and HASBLED scores, medications, type of invasive procedures and clinical events were recorded. Each patient underwent to TEE examination prior to the invasive procedure. Bridging anticoagulation was recommended only to patients with LA/LAA thrombus. We included 155 patients and mean CHA2DS2VASc score of the study population was 3.4 ± 1.4. Seventy-one of them had LA/LAA thrombi or SEC on TEE examination and bridging anticoagulation was applied. OAC treatment was not bridged in 8 of 11 patients with prior cerebrovascular accident and 17 of 31 patients with CHA2DS2VASc score of > 4. 57 of 124 patients with CHA2DS2VASc score of ≤ 4 required bridging anticoagulation. There were 14 major bleedings decided according to ISTH bleeding classification. Major bleeding was observed only in patients underwent to high-risk bleeding procedure. In conclusion CHA2DS2VASc score by itself is not enough for decision-making regarding ischemic risk. Furthermore, since major bleedings occurred only in patients underwent to high-risk bleeding surgery, TEE-based individualisation may be a feasible approach particularly for those with high thromboembolic risk undergoing high-bleeding risk procedure.

Thromboembolic events and need for anticoagulation therapy following left atrial appendage occlusion in patients with electrical isolation of the appendage.

INTRODUCTION: Electrical isolation of the left atrial appendage (LAA) is an important adjunctive ablation strategy in patients with nonparoxysmal atrial fibrillation (AF). Patients who have impaired LAA contractility following isolation may require long-term oral anticoagulant (OAC) therapy irrespective of their CHADS2 -VASc score. Percutaneous LAA occlusion (LAAO) is a potential alternative to life-long OAC therapy. We aimed to assess the rate of OAC discontinuation and thromboembolic (TE) events following percutaneous LAAO in patients who underwent LAA electrical isolation (LAAI). METHODS: This is a retrospective two-center study of patients who underwent percutaneous LAAO following LAAI. Patients with at least 3-month follow-up were included in the study. The antithrombotic therapy and TE events at the time of the last follow-up were noted. RESULTS: The LAA was successfully occluded in 162 (with Watchman device in 140 [86.4%] and Lariat in 22 [13.6%]). A total of 32 patients had leaks detected on the 45-day transesophageal echocardiogram (TEE); 21 (15%) Watchman and 11 (50%) Lariat cases (P = 0.0001). Two (one Watchman and one Lariat) of the 32 leaks were more than 5 mm. After the 45-day TEE, 150 (92.6%) patients were off-OAC. No TE events were reported in the 150 patients who stopped the anticoagulants. Four (2.47%) patients experienced stroke following the LAAO (three Watchman and one Lariat) procedure while on-OAC, two of which were fatal. At the median follow-up of 18.5 months, 159 (98.15%) patients were off-anticoagulant. CONCLUSION: Up to 98% of patients with LAAI could safely discontinue OAC after undergoing the appendage closure procedure.

Absence of Functional Nav1.8 Channels in Non-diseased Atrial and Ventricular Cardiomyocytes.

PURPOSE: Several studies have indicated a potential role for SCN10A/NaV1.8 in modulating cardiac electrophysiology and arrhythmia susceptibility. However, by which mechanism SCN10A/NaV1.8 impacts on cardiac electrical function is still a matter of debate. To address this, we here investigated the functional relevance of NaV1.8 in atrial and ventricular cardiomyocytes (CMs), focusing on the contribution of NaV1.8 to the peak and late sodium current (INa) under normal conditions in different species. METHODS: The effects of the NaV1.8 blocker A-803467 were investigated through patch-clamp analysis in freshly isolated rabbit left ventricular CMs, human left atrial CMs and human-induced pluripotent stem cell-derived CMs (hiPSC-CMs). RESULTS: A-803467 treatment caused a slight shortening of the action potential duration (APD) in rabbit CMs and hiPSC-CMs, while it had no effect on APD in human atrial cells. Resting membrane potential, action potential (AP) amplitude, and AP upstroke velocity were unaffected by A-803467 application. Similarly, INa density was unchanged after exposure to A-803467 and NaV1.8-based late INa was undetectable in all cell types analysed. Finally, low to absent expression levels of SCN10A were observed in human atrial tissue, rabbit ventricular tissue and hiPSC-CMs. CONCLUSION: We here demonstrate the absence of functional NaV1.8 channels in non-diseased atrial and ventricular CMs. Hence, the association of SCN10A variants with cardiac electrophysiology observed in, e.g. genome wide association studies, is likely the result of indirect effects on SCN5A expression and/or NaV1.8 activity in cell types other than CMs.

Cost-Effectiveness of Left Atrial Appendage Closure With the WATCHMAN Device Compared With Warfarin or Non-Vitamin K Antagonist Oral Anticoagulants for Secondary Prevention in Nonvalvular Atrial Fibrillation.

BACKGROUND AND PURPOSE: Once a patient with atrial fibrillation experiences an embolic event, the risk of a recurrent event increases 2.6-fold. New treatments have emerged as viable treatment alternatives to warfarin for stroke risk reduction in secondary prevention populations. This analysis sought to assess the cost-effectiveness of left atrial appendage closure (LAAC) compared with warfarin and the non-vitamin K antagonist oral anticoagulants dabigatran 150 mg, apixaban and rivaroxaban in the prevention of stroke in nonvalvular atrial fibrillation patients with a prior stroke or transient ischemic attack. METHODS: A Markov model was constructed using data from the secondary prevention subgroup analyses of the non-vitamin K antagonist oral anticoagulant and LAAC pivotal trials. Costs were from 2016 US Medicare reimbursement rates and the literature. The cost-effectiveness analysis was conducted from a US Medicare perspective over a lifetime (20 years) horizon. The model was populated with a cohort of 10 000 patients aged 70 years with a CHA2DS2-VASc score of 7 (annual stroke risk=9.60%) and HAS-BLED score of 3 (annual bleeding risk=3.74%). RESULTS: LAAC achieved cost-effectiveness relative to dabigatran at year 5 and warfarin and apixaban at year 6. At 10 years, LAAC had more quality-adjusted life years (4.986 versus 4.769, 4.869, 4.888, and 4.810) and lower costs ($42 616 versus $53 770, $58 774, $55 656, and $58 655) than warfarin, dabigatran, apixaban, and rivaroxaban, respectively, making LAAC the dominant (more effective and less costly) stroke risk reduction strategy. LAAC remained the dominant strategy over the lifetime analysis. CONCLUSIONS: Upfront procedure costs initially make LAAC higher cost than warfarin and the non-vitamin K antagonist oral anticoagulants, but within 10 years, LAAC delivers more quality-adjusted life years and has lower total costs, making LAAC the most cost-effective treatment strategy for secondary prevention of stroke in atrial fibrillation.

[Effect of non-vitamin K antagonist oral anticoagulants on left atrial or atrial appendage thrombi in patients with nonvalvular atrial fibrillation].

Objective: To investigate the effect of non-vitamin K antagonist oral anticoagulants (NOAC) on left atrial or atrial appendage (LA/LAA) thrombi in patients with nonvalvular atrial fibrillation (NVAF). Method: Data from 3 042 patients with atrial fibrillation(AF), who underwent transesophageal echocardiography (TEE) examination before cardioversion or catheter ablation for the detection of LA/LAA thrombus in our department from March 2016 to January 2018 were prospectively analyzed. Among these patients, LA/LAA thrombus was detected by TEE in 57 patients. A total of 19 patients who received dabigatran or rivaroxaban for ≥3 weeks and underwent repeated TEE were included, 38 patients were excluded (7 patients with rheumatic heart disease, 1 patient treated with pericardial decortication, 1 patient treated with surgical repair of endocardial cushion defect, 1 patient with LA thrombus associated with the atrial septal occluder device, 14 patients received warfarin therapy, 14 patients did not receive repeated TEE). Results: First repeated TEE results showed that LA/LAA thrombus was not completely resolved in 4 out of 4 patients treated with dabigatran (110 mg bid) for a median time of 119 (47, 258) days, whereas LA/LAA thrombus was completely resolved in 5 out of 11 patients treated with dabigatran (150 mg bid) for a median time of 80 (58, 147) days. Thrombus was completely resolved in 2 out of 2 patients treated with rivaroxaban (15 mg qd) for 110 days and 95 days respectively, and in 1 out of 2 patients treated with rivaroxaban (20 mg qd) for 91 days. Second repeated TEE was performed in 8 patients. Thrombus was resolved completely in 2 out of 3 patients with undissolved thrombus treated by dabigatran (110 mg bid) after increasing the dabigatran dosage (150 mg bid). Thrombus was resolved in 3 (1 patient prolonged treatment with dabigatran 150 mg bid and 2 patients switched to rivaroxaban 20 mg qd) out of 4 patients with undissolved thrombus under the dabigatran 150 mg bid regimen, whereas the thrombus remained unresolved in 1 patient switched to rivaroxaban (15 mg qd). After receiving rivaroxaban 15 mg bid treatment, the thrombus was finally resolved in 1 patient with undissolved thrombus treated by rivaroxaban 20 mg qd. There was no clinical thromboembolism or major bleeding events during the median follow up time of 462 (305, 558) days. Conclusions: Our data show that NOAC is an effective therapeutic option for the treatment of LA/LAA thrombi. When eligible, a higher NOAC dosage may be preferred due to the higher efficacy on thrombus resolvement.

Acetylcholine-Atropine Interactions: Paradoxical Effects on Atrial Fibrillation Inducibility.

Atropine (ATr) is well known as a cholinergic antagonist, however, at low concentrations ATr could paradoxically accentuate the parasympathetic actions of acetylcholine (ACh). In 22 pentobarbital anesthetized dogs, via a left and right thoracotomy, a leak-proof barrier was attached to isolate the atrial appendages (AAs) from the rest of the atria. In group 1 (Ach+ATr+Ach), ACh, 100 mM, was placed on the AA followed by the application of ATr, 2 mg/mL. The average atrial fibrillation (AF) duration was 17 ± 7 minutes. After ATr was applied to the AA and ACh again tested, the AF duration was markedly attenuated (2 ± 2 minutes, P < 0.05). In group 2 (ATr+Ach), ATr was initially applied to the AA followed by the application of ACh, 100 mM. There was no significant difference in AF duration (16 ± 4 minutes vs. 18 ± 2 minutes, P = NS). The inhibitory effect of ATr on induced HR reduction (electrical stimulation of the anterior right ganglionated plexi and vagal nerves) was similar between groups 1 and 2. These observations suggest that when ATr is initially administered it attaches to the allosteric site of the muscarinic ACh receptor (M2) leaving the orthosteric site free to be occupied by ACh. The M3 receptor that controls HR slowing does not show the same allosteric properties.

In-vitro examination of the positive inotropic effect of caffeine and taurine, the two most frequent active ingredients of energy drinks.

BACKGROUND: Our study aimed to evaluate changes in the contractile behavior of human myocardium after exposure to caffeine and taurine, the main active ingredients of energy drinks (EDs), and to evaluate whether taurine exhibits any inotropic effect at all in the dosages commonly used in EDs. METHODS: Myocardial tissue was removed from the right atrial appendages of patients undergoing cardiac surgery and prepared to obtain specimens measuring 4 mm in length. A total of 92 specimens were exposed to electrical impulses at a frequency of 75 bpm for at least 40 min to elicit their maximum contractile force before measuring the isometric contractile force (ICF) and duration of contraction (CD). Following this, each specimen was treated with either taurine (group 1, n = 29), or caffeine (group 2, n = 31) or both (group 3, n = 32). After exposure, ICF and CD measuring were repeated. Post-treatment values were compared with pre-treatments values and indicated as percentages. RESULTS: Exposure to taurine did not alter the contraction behavior of the specimens. Exposure to caffeine, in contrast, led to a significant increase in ICF (118 ± 03%, p < 0.01) und a marginal decrease in CD (95 ± 1.6%, p < 0.01). Exposure to a combination of caffeine and taurine also induced a statistically significant increase in ICF (124 ± 4%, p < 0.01) and a subtle reduction in CD (92 ± 1.4%, p < 0.01). The increase in ICF achieved by administration of caffeine was similar to that achieved by a combination of both caffeine and taurine (p = 0.2). The relative ICF levels achieved by administration of caffeine and a combination of taurine and caffeine, respectively, were both significantly higher (p < 0.01) than the ICF resulting from exposure to taurine only. CONCLUSION: While caffeine altered the contraction behavior of the specimen significantly in our in-vitro model, taurine did not exhibit a significant effect. Adding taurine to caffeine did not significantly enhance or reduce the effect of caffeine.

Left Atrial Appendage Closure in Patients with Atrial Fibrillation and Previous Intracerebral Hemorrhage.

BACKGROUND: Percutaneous left atrial appendage closure (LAAC) may be considered in patients with atrial fibrillation and contraindication for long-term anticoagulation. This study aimed to assess the safety and efficacy of LAAC followed by single antiplatelet therapy in patients with atrial fibrillation and previous spontaneous intracerebral hemorrhage (ICH). METHODS: In this explorative, prospective, single-center study, consecutive patients who underwent LAAC because of previous spontaneous ICH over a period of 4 years were analyzed. Risks of ischemic strokes and hemorrhagic complications were estimated using the CHA2DS2-VASc and HAS-BLED scores, respectively. Single antiplatelet therapy was given for at least 6 months post implantation. Clinical follow-up included cardiological evaluations at 1, 3, 6, and 12 months, and neurological evaluations at 3 and 12 months. RESULTS: A total of 46 patients underwent LAAC with a mean follow-up of 12 ± 7 months. The observed annual rate of ischemic stroke was 4.35% compared with an expected rate of 7.23% according to the mean risk of the population based on CHA2DS2-VASc score, which translated into a 40% risk reduction. The observed annual rate of major bleeding was 4.35% compared with an expected rate of 8.05% according to the mean risk of the population based on HAS-BLED score, which translated into a 46% risk reduction. CONCLUSIONS: LAAC followed by single antiplatelet therapy is feasible as an alternative to oral anticoagulation in high-risk patients with previous ICH, with an acceptable periprocedural risk. Longer follow-up in a larger number of patients will be needed to establish the effectiveness of LAAC relative to direct oral anticoagulants.

Resolving Thrombus in the Left Atrial Appendage by Edoxaban Treatment after Acute Ischemic Stroke: Report of 2 Cases.

Here we report first 2 cases of patients with nonvalvular atrial fibrillation with acute cardioembolic stroke in whom thrombi in the left atrial appendage (LAA) were resolved by edoxaban administration. Case 1 reports an 86-year-old woman who suddenly showed right hemiparesis and aphasia due to occlusion of the left middle cerebral artery. She received mechanical thrombectomy and recovered neurologically. Transesophageal echocardiography (TEE) performed on day 1 demonstrated thrombus in the LAA. The thrombus was resolved on day 13 after initiation of edoxaban (30 mg once daily) instead of warfarin, which was administered before stroke onset. Case 2 reports a 49-year-old man who was admitted because of the sudden onset of left hemiparesis and aphasia. TEE demonstrated thrombus in the LAA on day 4, and edoxaban therapy (60 mg once daily) was initiated. The thrombus resolution was observed on day 16, and no embolic stroke occurred.

Tetrandrine reverses human cardiac myofibroblast activation and myocardial fibrosis.

Tetrandrine (TTD) is a calcium channel blocker with documented antifibrotic actions. In this study, for the first time, we identified that TTD can directly prevent in vitro human cardiac myofibroblast activation and limit in vivo myocardial fibrosis. In vitro, cardiac myofibroblasts from human atrial biopsies (N = 10) were seeded in three-dimensional collagen matrices. Cell-collagen constructs were exposed to transforming growth factor-ß1 (10 ng/ml), with or without TTD (1 and 5 µM) for 48 h. Collagen gel contraction, myofibroblast activation (α-smooth muscle actin expression), expression of profibrotic mRNAs, and rate of collagen protein synthesis were compared. TTD decreased collagen gel contraction (79.7 ± 1.3 vs 60.1 ± 8.9%, P < 0.01), α-smooth muscle actin expression (flow cytometry), collagen synthesis ([(3)H]proline incorporation), and collagen mRNA expression. Cell viability was similar between groups (annexin positive cells: 1.7 vs. 1.4%). TTD inhibited collagen gel contraction in the presence of T-type and L-type calcium channel blockers, and the intracellular calcium chelator BAPTA-AM (15 µM), suggesting that the observed effects are not mediated by calcium homeostasis. In vivo, Dahl salt-sensitive hypertensive rats were treated with variable doses of TTD (by intraperitoneal injection over 4 wk) and compared with untreated controls (N = 12). Systemic blood pressure was monitored by tail cuff. Myocardial fibrosis and left ventricular compliance were assessed by histology and passive pressure-volume analysis. Myocardial fibrosis was attenuated compared with untreated controls (%collagen area: 9.4 ± 7.3 vs 2.1 ± 1.0%, P < 0.01). Left ventricular compliance was preserved. In conclusion, TTD reverses human cardiac myofibroblast activation and myocardial fibrosis, independent of calcium channel blockade.

Altered apoptosis-related signaling after cardioplegic arrest in patients with uncontrolled type 2 diabetes mellitus.

BACKGROUND: We investigated the effects of cardioplegic arrest and reperfusion (CP/Rep) on myocardial apoptosis and key apoptotic mediators, such as apoptosis-inducing factor, caspase 3, caspase 8, caspase 9, poly(adenosine diphosphate-ribose) polymerase, B-cell lymphoma 2 (Bcl-2) family proteins, and protein kinase C (PKC), in uncontrolled type 2 diabetic, controlled type 2 diabetic, and nondiabetic patients. METHODS AND RESULTS: Right atrial tissue was harvested pre- and post-CP/Rep from uncontrolled type 2 diabetic patients (hemoglobin A1c=9.6 ± 0.25), controlled type 2 diabetic patients (hemoglobin A1c=6.5 ± 0.15), and nondiabetic patients (hemoglobin A1c=5.4 ± 0.12) undergoing coronary artery bypass grafting (n=8/group). Terminal deoxynucleotidyl transferase dUTP nick-end labeling staining was used for the identification of apoptotic cells. Total and modified apoptosis-inducing factor, Bcl-2 family proteins, phospho-PKC-α, phospho-PKC-ß1, and poly(adenosine diphosphate-ribose) polymerase were quantified by immunoblotting or immunohistochemistry. At baseline, the number of apoptotic cells and expression of total apoptosis-inducing factor, Bcl-2, Bak, and Bax in the pre-CP/Rep atrial tissue from uncontrolled type 2 diabetic patients were significantly increased compared with those of nondiabetic or controlled type 2 diabetic patients (P<0.05). After CP/Rep, the amount of apoptotic cells, apoptosis-inducing factor, phospho-Bad, phospho-PKC-α, phospho-PKC-ß1, and cleaved poly(adenosine diphosphate-ribose) polymerase in post-CP/Rep atrial tissue were increased in all 3 groups compared with pre-CP/Rep. These increases after CP/Rep were more pronounced in the uncontrolled type 2 diabetic group. In addition, there were significant increases in the expression of cleaved caspase 8 and caspase 9 in the basal and post-CP/Rep atrium of uncontrolled type 2 diabetic group compared with nondiabetic or controlled type 2 diabetic group. CONCLUSIONS: Uncontrolled diabetes mellitus is associated with increases in myocardial apoptosis and expression of key apoptosis mediators at baseline and in the setting of CP/Rep.

Percutaneous left atrial appendage closure for stroke prophylaxis in patients with atrial fibrillation: 2.3-Year Follow-up of the PROTECT AF (Watchman Left Atrial Appendage System for Embolic Protection in Patients with Atrial Fibrillation) Trial.

BACKGROUND: The multicenter PROTECT AF study (Watchman Left Atrial Appendage System for Embolic Protection in Patients With Atrial Fibrillation) was conducted to determine whether percutaneous left atrial appendage closure with a filter device (Watchman) was noninferior to warfarin for stroke prevention in atrial fibrillation. METHODS AND RESULTS: Patients (n=707) with nonvalvular atrial fibrillation and at least 1 risk factor (age >75 years, hypertension, heart failure, diabetes, or prior stroke/transient ischemic attack) were randomized to either the Watchman device (n=463) or continued warfarin (n=244) in a 2:1 ratio. After device implantation, warfarin was continued for ≈45 days, followed by clopidogrel for 4.5 months and lifelong aspirin. Study discontinuation rates were 15.3% (71/463) and 22.5% (55/244) for the Watchman and warfarin groups, respectively. The time in therapeutic range for the warfarin group was 66%. The composite primary efficacy end point included stroke, systemic embolism, and cardiovascular death, and the primary analysis was by intention to treat. After 1588 patient-years of follow-up (mean 2.3±1.1 years), the primary efficacy event rates were 3.0% and 4.3% (percent per 100 patient-years) in the Watchman and warfarin groups, respectively (relative risk, 0.71; 95% confidence interval, 0.44%-1.30% per year), which met the criteria for noninferiority (probability of noninferiority >0.999). There were more primary safety events in the Watchman group (5.5% per year; 95% confidence interval, 4.2%-7.1% per year) than in the control group (3.6% per year; 95% confidence interval, 2.2%-5.3% per year; relative risk, 1.53; 95% confidence interval, 0.95-2.70). CONCLUSIONS: The "local" strategy of left atrial appendage closure is noninferior to "systemic" anticoagulation with warfarin. PROTECT AF has, for the first time, implicated the left atrial appendage in the pathogenesis of stroke in atrial fibrillation. CLINICAL TRIAL REGISTRATION: : URL: http://www.clinicaltrials.gov. Unique identifier: NCT00129545.

Pharmacological prevention and termination of focal atrial fibrillation.

AIMS: Patients undergo ablation for focal atrial fibrillation (AF) as a result of failure of anti-arrhythmic drugs. Our basic studies have implicated cholinergic and adrenergic neurotransmitter release as the underlying mechanism for focal AF. Therefore, we tested the efficacy of a combination of sodium channel-blocking agents with additional vagolytic properties and a ß-blocker to terminate and prevent focal AF. METHODS AND RESULTS: In 18 Na-pentobarbital-anaesthetized dogs, after a right or left thoracotomy, acetylcholine (Ach, 0.5 cc, 100 mM) was injected into a fat pad containing ganglionated plexi (GP) or applied on an atrial appendage (AA) to induce focal firing at the pulmonary veins (PVs) or AA, respectively. Disopyramide (2-4 mg/kg, n= 6) or quinidine (3-6 mg/kg, n= 12) combined with esmolol or propranolol (1 mg/kg, n= 13 and 5, respectively) were slowly injected to terminate (Group I, n= 12) or prevent (Group II, n= 6) Ach-induced sustained focal AF. In another four dogs, only the sodium channel-blocking agents with additional vagolytic properties or only the ß-blocker was injected prior to or after the initiation of focal AF. At baseline, the mean duration of AF induced by Ach was 26 ± 4 min. Group I: After drugs, Ach-induced AF duration was 3 ± 1 min (P< 0.001). Group II: Prior to drugs, Ach-induced AF lasted for 19 ± 3 min. With the drug combination the duration of Ach-induced AF, decreased to 6 ± 1/min, P< 0.001. Either quinidine or propranolol alone did not change the duration of Ach-induced AF, mean 25 ± 10 min compared with Ach alone, 28 ± 16 min, P= 0.2. CONCLUSIONS: Type IA (cholinergic antagonist) plus Type II (ß-adrenergic antagonist) provides significant prevention and suppression of focal AF arising at PV and non-PV sites.

Protection of human myocardium by bone marrow cells: role of long-term administration of the mitochondrial K(ATP) channel opener nicorandil.

BACKGROUND: We have previously demonstrated that bone marrow cells (BMCs) afford myocardial protection as potent as ischemic preconditioning (IP) and also that the myocardium of patients treated with the mitoK(ATP) channel opener nicorandil cannot be protected by IP. Here, we investigated whether nicorandil influences the cardioprotection elicited by BMCs and whether any loss in protection can be rescued by naïve allogenic BMCs. MATERIALS AND METHODS: BMCs and right atrial appendage were obtained from patients on long-term treatment and nontreated with nicorandil. The atrial myocardium was subjected to 90 min ischemia/120 min reoxygenation at 37°C in the presence and absence of autologous and allogenic BMCs. Some muscles were subjected to IP prior to ischemia and served as positive controls. Tissue injury was assessed by creatine kinase released during reoxygenation, and cell necrosis and apoptosis were determined by propidium iodide and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL). RESULTS: Creatine kinase (CK) release and cell necrosis and apoptosis induced by ischemia were not significantly reduced by IP in the myocardium from nicorandil subjects and values were also unaffected by the co-incubation with autologous or allogenic BMCs from subjects not treated with nicorandil (naïve BMCs). However, when the myocardium from subjects not treated with nicorandil was co-incubated with autologous BMCs or with allogenic BMCs from subjects treated with nicorandil, there was a similar significant reduction in CK release, cell necrosis and apoptosis. CONCLUSIONS: The cardioprotective properties of BMCs from subjects treated with the mitoK(ATP) channel opener nicorandil are preserved; however, the myocardium of these patients cannot benefit from the cardioprotective effect of BMCs due to an unresponsive myocardium.

Modulation of the nitric oxide metabolism overcomes the unresponsiveness of the diabetic human myocardium to protection against ischemic injury.

BACKGROUND: We have demonstrated that diabetic human myocardium cannot be protected by ischemic preconditioning (IP) and identified a dysfunction of the mitochondria as the cause of the defect. Here we have investigated whether modulation of the nitric oxide (NO) metabolism can overcome the unresponsiveness of the diabetic myocardium to cardioprotection. METHODS: Myocardial slices (30-40 mg) obtained from the right atrial appendage of patients with diabetes undergoing elective cardiac surgery were randomized to the following protocol (n=6/group): NO donor SNAP (100 µM), nonselective nitric oxide synthase (NOS) inhibitor L-NAME (100 µM), and selective neuronal NOS (nNOS) inhibitor TRIM (100 µM) for 20 min prior to 90 min ischemia followed by 120 min reoxygenation (37°C). Some preparations were subjected to ischemic/reoxygenation alone or to IP (5 min ischemia/5 min reoxygenation) to act as control. Tissue injury was assessed by creatine kinase (CK) released (IU/mg wet wt), and cell necrosis and apoptosis by propidium iodide and TUNEL (% of aerobic control). RESULTS: IP did not decrease CK release, cell necrosis or apoptosis in diabetic myocardium. However, NO donor SNAP, the nonspecific NOS inhibitor L-NAME, and the specific nNOS inhibitor TRIM significantly reduced CK leakage, cell necrosis, and apoptosis in diabetic myocardium. CONCLUSIONS: These results demonstrate that both the provision of exogenous NO and the suppression of endogenous NO production result in potent protection of diabetic human myocardium overcoming the unresponsiveness of these tissues to cardioprotective therapies.

Local activation times at the high posterior wall of the left atrium during left atrial appendage pacing predict roof line block with high specificity and sensitivity.

AIMS: Ensuring complete block after left atrial (LA) linear lesions is important as partial block may be pro-arrhythmic. Techniques to confirm roof line block may be time consuming and challenging and have not been well described. This study investigates whether local activation times (LAT) during left atrial appendage (LAA) pacing help in the assessment of roof line block. METHODS AND RESULTS: Forty-five patients underwent ablation for atrial fibrillation (AF) including circumferential pulmonary vein isolation, roof, and mitral isthmus lines. Local activation times were measured at pre-defined points on the posterior wall and high anterior wall during LAA pacing at the following stages: (i) baseline; (ii) incomplete roof line; (iii) roof block; and (iv) roof and mitral isthmus block. Time from pacing at high posterior wall to LAA was also recorded at each stage. Receiver operator curve analyses were performed on different parameters to assess if they could confirm roof line block. There was a stepwise increase in mean high posterior wall LAT: 83 ± 16 ms (baseline); 105 ± 20 ms (incomplete roof block); 133 ± 26 ms (roof block), and 152 ± 35 ms (roof and MI block; one way analysis of variance, P< 0.0001). Increased LA diameter, amiodarone use, and adjunctive complex fractionated atrial electrogram ablation were associated with longer LATs. For patients with persistent AF, LAA to high posterior wall times of >133 ms, high posterior wall to LAA times of >125 ms and double potential >77 ms predict roof line block with high specificity and sensitivity especially if there was also mitral isthmus block. CONCLUSION: Parameters derived from the measurement of LAT of the high posterior and anterior LA wall help guide the assessment of roof line block.