A cost-utility analysis for catheter ablation of atrial fibrillation in combination with warfarin and dabigatran based on the CHADS2 score in Japan

BACKGROUND

We aimed to clarify the cost-effectiveness of an expensive combination therapy for atrial fibrillation (AF) using both catheter ablation and dabigatran compared with warfarin at each CHADS₂ score for patients in Japan.

METHODS

A Markov model was constructed to analyze costs and quality-adjusted life years associated with AF therapeutic options with a time horizon of 10 years. The target population was 60-year-old patients with paroxysmal AF. The indication for anticoagulation was determined according to the Japanese guideline. Anticoagulation-related data were derived from the RE-LY study and the AF recurrence rate was set at 2.7% per month during the first 12 months and at 0.40% per month afterwards. Stroke risk was determined according to AF recurrence, anticoagulation, and CHADS₂ score. The risks for stroke recurrence and stroke death were also considered. Costs were calculated from the healthcare payer's perspective, and only direct medical costs were included.

RESULTS

Warfarin was the most preferred option for patients with a CHADS₂ score of 0 from a health economics aspect. Ablation under warfarin was preferred for a CHADS₂ score of 1-3, while ablation under dabigatran was preferred for a CHADS₂ score ≥4. The quality of life score for AF had the largest impact on the incremental cost-effectiveness ratios in the analysis between the anticoagulation arm and the anticoagulation+ablation arm for a CHADS₂ score of 2. Within the range of the Japanese willingness-to-pay threshold (¥5,000,000), the ablation+warfarin arm became the best option with its probability of 81.7% for a CHADS₂ score of 2; the dabigatran+ablation arm was the most preferred option with its probability of 56.1% for a CHADS₂ score of 4.

CONCLUSIONS

Ablation under dabigatran therapy is an expensive therapeutic option, but it might benefit patients with a low quality of life and a high CHADS₂ score.

Left Atrial LGE and Arrhythmia Recurrence Following Pulmonary Vein Isolation for Paroxysmal and Persistent AF

OBJECTIVES

The aims of this study were to: 1) use a novel method of late gadolinium enhancement (LGE) quantification that uses normalized intensity measures to confirm the association between LGE extent and atrial fibrillation (AF) recurrence following ablation; and 2) examine the presence of interaction and effect modification between LGE and AF persistence.

BACKGROUND

Recurrent AF after catheter ablation has been reported to associate with the baseline extent of left atrial LGE on cardiac magnetic resonance. Traditional methods for measurement of intensity lack an objective threshold for quantification and interpatient comparisons of LGE.

METHODS

The cohort included 165 participants (mean age 60.0 ± 10.2 years, 77% men, 57% with persistent AF) who underwent initial AF ablation. The association of baseline LGE extent with AF recurrence was examined using multivariable Cox proportional hazards models. Multiplicative and additive interactions between AF type and LGE extent were examined.

RESULTS

During 10.2 ± 5.7 months of follow-up, 63 patients (38.2%) experienced AF recurrence. Baseline LGE extent was independently associated with AF recurrence after adjusting for confounders (hazard ratio: 1.5 per 10% increased LGE; p < 0.001). The hazard ratio for AF recurrence progressively increased as a function of LGE. The magnitude of association between LGE >35% and AF recurrence was greater among patients with persistent AF (hazard ratio: 6.5 [p = 0.001] vs. 3.6 [p = 0.001]); however, there was no evidence for statistical interaction.

CONCLUSIONS

Regardless of AF persistence at baseline, participants with LGE ≤35% have favorable outcomes, whereas those with LGE >35% have a higher rate of AF recurrence in the first year after ablation. These findings suggest a role for: 1) patient selection for AF ablation using LGE extent; and 2) substrate modification in addition to pulmonary vein isolation in patients with LGE extent exceeding 35% of left atrial myocardium.

Quantitative tissue-tracking cardiac magnetic resonance (CMR) of left atrial deformation and the risk of stroke in patients with atrial fibrillation

BACKGROUND

Recent evidence suggests that left atrial (LA) dysfunction may be mechanistically contributing to cerebrovascular events in patients with atrial fibrillation (AF). We investigated the association between regional LA function and a prior history of stroke during sinus rhythm in patients referred for catheter ablation of AF.

METHODS AND RESULTS

A total of 169 patients (59 ± 10 years, 74% male, 29% persistent AF) with a history of AF in sinus rhythm at the time of pre-ablation cardiac magnetic resonance (CMR) were analyzed. The LA volume, emptying fraction, strain (S), and strain rate (SR) were assessed by tissue-tracking cardiac magnetic resonance. The patients with a history of stroke or transient ischemic attack (n=18) had greater LA volumes (Vmax and Vmin; P=0.02 and P<0.001, respectively), lower LA total emptying fraction (P<0.001), lower LA maximum and pre-atrial contraction strains (Smax and SpreA; P<0.001 and P=0.01, respectively), and lower absolute values of LA SR during left ventricular (LV) systole and early diastole (SRs and SRe; P=0.005 and 0.03, respectively) than those without stroke/transient ischemic attack (n=151). Multivariable analysis demonstrated that the LA reservoir function, including total emptying fraction, Smax, and SRs, was associated with stroke/transient ischemic attack (odds ratio 0.94, 0.91, and 0.17; P=0.03, 0.02, and 0.04, respectively) after adjusting for the CHA2DS2-VASc score and LA Vmin.

CONCLUSIONS

Depressed LA reservoir function assessed by tissue-tracking cardiac magnetic resonance is significantly associated with a prior history of stroke/transient ischemic attack in patients with AF. Our findings suggest that assessment of LA reservoir function can improve the risk stratification of cerebrovascular events in AF patients.

Antidepressant and anxiolytic profiles of newly synthesized arginine vasopressin V1B receptor antagonists: TASP0233278 and TASP0390325

BACKGROUND AND PURPOSE

Vasopressin V1B receptor antagonists may be effective for the treatment of depression and anxiety and the objective of this study was to characterize the pharmacological profiles of two newly synthesized arginine vasopressin receptor 1B (V1B receptor) antagonists, TASP0233278 and TASP0390325.

EXPERIMENTAL APPROACH

We investigated the in vitro profiles of TASP0233278 and TASP0390325. In addition, the effect of TASP0390325 on the increase in plasma adrenocorticotropic hormone (ACTH) levels induced by corticotropin-releasing factor (CRF)/desmopressin (dDAVP) was investigated. We also investigated the antidepressant and anxiolytic profiles of TASP0233278 and TASP0390325 in animal models.

KEY RESULTS

Both TASP0233278 and TASP0390325 showed a high affinity and potent antagonist activity for V1B receptors. Oral administration of TASP0390325 antagonized the increase in plasma ACTH levels induced by CRF/dDAVP in rats, indicating that TASP0390325 blocks the anterior pituitary V1B receptor in vivo. Oral administration of TASP0233278 or TASP0390325 also exerted antidepressant effects in two models of depression (a forced swimming test and an olfactory bulbectomy model). Moreover, TASP0233278 improved depressive-like behaviour induced by repeated treatment with corticosterone, a model that has been shown to be resistant to treatment with currently prescribed antidepressants. In addition to depression models, TASP0233278 or TASP0390325 exerted anxiolytic effects in several anxiety models (social interaction, elevated plus-maze, stress-induced hyperthermia, separation-induced ultrasonic vocalization and sodium lactate-induced panic-like responses in panic-prone rats).

CONCLUSION

TASP0233278 and TASP0390325 are potent and orally active V1B receptor antagonists with antidepressant and anxiolytic activities in rodents.

Association of left atrial function and left atrial enhancement in patients with atrial fibrillation: cardiac magnetic resonance study

BACKGROUND

Atrial fibrillation (AF) is associated with left atrial (LA) structural and functional changes. Cardiac magnetic resonance late gadolinium enhancement (LGE) and feature-tracking are capable of noninvasive quantification of LA fibrosis and myocardial motion, respectively. We sought to examine the association of phasic LA function with LA enhancement in patients with AF.

METHODS AND RESULTS

LA structure and function was measured in 90 patients with AF (age 61±10 years; 76% men) referred for ablation and 14 healthy volunteers. Peak global longitudinal LA strain, LA systolic strain rate, and early and late diastolic strain rates were measured using cine-cardiac magnetic resonance images acquired during sinus rhythm. The degree of LGE was quantified. Compared with patients with paroxysmal AF (60% of cohort), those with persistent AF had larger maximum LA volume index (56±17 versus 49±13 mL/m(2); P=0.036), and increased LGE (27.1±11.7% versus 36.8±14.8%; P<0.001). Aside from LA active emptying fraction, all LA parameters (passive emptying fraction, peak global longitudinal LA strain, systolic strain rate, early diastolic strain rate, and late diastolic strain rate) were lower in patients with persistent AF (P<0.05 for all). Healthy volunteers had less LGE and higher LA functional parameters compared with patients with AF (P<0.05 for all). In multivariable analysis, increased LGE was associated with lower LA passive emptying fraction, peak global longitudinal LA strain, systolic strain rate, early diastolic strain rate, and late diastolic strain rate (P<0.05 for all).

CONCLUSIONS

Increased LA enhancement is associated with decreased LA reservoir, conduit, and booster pump functions. Phasic measurement of LA function using feature-tracking cardiac magnetic resonance may add important information about the physiological importance of LA fibrosis.

Left atrial strain is a powerful predictor of atrial fibrillation recurrence after catheter ablation: study of a heterogeneous population with sinus rhythm or atrial fibrillation

AIMS

Accumulating data show the efficacy of catheter ablation (CA) for atrial fibrillation (AF); however, postoperative recurrence is not uncommon. The aim of this study was to identify predictors of AF recurrence in patients undergoing CA.

METHODS AND RESULTS

We studied 100 patients with symptomatic paroxysmal (68) or persistent (32) AF who underwent CA preceded by transthoracic echocardiographic examination. Of these, 50 had sinus rhythm during echocardiography (Group NSR) and 50 had AF rhythm (Group AF). The left atrial (LA) strain was measured by two-dimensional speckle tracking echocardiography. Echocardiographic parameters were compared between the patients with AF recurrence and no recurrence. During 12 months of follow-up, 26 of 100 patients (11 in Group NSR and 15 in Group AF) had AF recurrence; these patients had significantly longer AF duration, a lower LA global strain (LA-GS), lower LA lateral total strain (LA-LS), and larger maximum LA volume index (LAVImax) than those who maintained sinus rhythm. Multivariate logistic regression identified basal LA-LS and LAVImax as independent predictors of AF recurrence. Furthermore, receiver operating characteristic analyses revealed that basal LA-LS was the most useful parameter for predicting AF recurrence [area under the curve (AUC): 0.84 vs. 0.74 in LAVImax]. Subanalyses showed that LAVImax was another independent predictor of AF recurrence in Group AF, but not in Group NSR, while basal LA-LS was a significant predictor in both groups.

CONCLUSION

LA myocardial function assessed by basal LA-LS could predict AF recurrence after CA. Notably, such an assessment could be applicable even during AF rhythm, suggesting its convenience in the clinical setting without defibrillation before analysis.

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-β, 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.

Electrophysiological properties of the superior vena cava and venoatrial junction in patients with atrial fibrillation: relevance to catheter ablation

BACKGROUND

Although the superior vena cava (SVC) has been well known to be one of the important foci triggering atrial fibrillation (AF), its electrophysiological characteristics have received little research attention. The aim of this study was to investigate the electrophysiological properties of the SVC and venoatrial junction (VAJ).

METHODS

Twenty-five consecutive AF patients without structural heart disease undergoing electrical SVC isolation were included in this study. After pulmonary vein isolation, a circular decapolar catheter and 2 multipolar catheters were emplaced in the VAJ, right atrial appendage (RAA), and SVC, respectively. Burst pacing and single extrastimulus were applied from the RAA and SVC. The atrial and caval potentials on the circular catheter in the VAJ were investigated.

RESULTS

Intracaval conduction delay and various degrees of conduction block over the VAJ were observed with burst pacing from both the RAA and SVC. A single extrastimulus from the RAA and SVC with a basic cycle length of 600 milliseconds prolonged the conduction time via the VAJ by 81 ± 49.7 milliseconds and 61 ± 58.7 milliseconds, respectively. The atrial and caval electrograms at the VAJ, which were separated from each other by pacing applications, facilitated mapping of the earliest activation site at the VAJ.

CONCLUSIONS

Intracaval conduction delay and decremental conduction property via the VAJ were demonstrated using pacing maneuvers. Pacing applications from the RAA or SVC can help distinguish the atrial and caval potentials and can facilitate mapping of the optimal ablation sites to isolate the SVC.

Time to first cigarette and lung cancer risk in Japan

BACKGROUND

Cigarette smoking is the major cause of lung cancer (LC). Although the time to first cigarette (TTFC) of the day is a distinct indicator of nicotine dependence, little information is available on its possible relation to LC.

PATIENTS AND METHODS

This case-control study includes a total of 1572 incident LC cases and 1572 non-cancer controls visiting for the first time the Aichi Cancer Center Hospital between 2001 and 2005. We estimated the odds ratio (OR) and 95% confidence interval (CI) for TTFC using a logistic regression model after adjustment for several potential confounders.

RESULTS

TTFC was inversely associated with the risk of LC. This association was consistent across histological subtypes of LC. For all LCs considered among ever smokers and after accurate allowance for smoking quantity and duration, besides other relevant covariates, compared with TTFC >60 min, the adjusted ORs were 1.08 (95% CI, 0.73-1.61) for TTFC of 31-60 min, 1.40 (0.98-2.01) for 6-30 min and 1.86 (1.28-2.71) for within 5 min (Ptrend, < 0.001). Statistically marginally significant heterogeneity by histological subtype was observed (Pheterogeneity, 0.002).

CONCLUSIONS

Nicotine dependence, as indicated by the TTFC, is associated with increased risk of LC and is therefore an independent marker of exposure to tobacco smoking.

Nonthermal cardiac catheter ablation using photodynamic therapy

BACKGROUND

Radiofrequency ablation has limitations, largely related to creation of lesions by heating. Here, we report the first nonthermal ablation by applying photodynamic therapy (PDT) to cardiac tissues using a custom-made deflectable laser catheter. The present study investigated the feasibility of PDT for cavotricuspid isthmus ablation in a canine model.

METHODS AND RESULTS

We evaluated the pharmacokinetic profiles of 17 canines after administration of a photosensitizer (talaporfin sodium) by various protocols. We succeeded in maintaining the photosensitizer concentration at a level in excess of the clinically effective dose for humans. Using a 4-polar 7-French deflectable laser catheter, we performed PDT-mediated cavotricuspid isthmus ablation in 8 canines. PDT caused oxidative injury only to the irradiated area and successfully produced a persistent electric conduction block. No acute, gross changes such as edematous degeneration, thrombus formation, steam pops, or traumatic injury were observed after irradiation. Hematoxylin and eosin staining of tissues samples also showed well-preserved endothelial layers. Testing of the blood samples taken before and after the procedure revealed no remarkable changes. Lesion size at 2 weeks after the procedure and the temperature data collected during irradiation were compared between the PDT and irrigated radiofrequency ablation procedures. A ventricular cross-section revealed a solid PDT lesion, which was as deep as a radiofrequency lesion. In addition, endocardial, surficial, and intramural temperature monitoring during the PDT irradiation clearly demonstrated the nonthermal nature of the ablation technique.

CONCLUSIONS

Nonthermal PDT-mediated catheter ablation is a potentially novel treatment for cardiac arrhythmias.

Storms of ventricular fibrillation responsive to isoproterenol in an idiopathic ventricular fibrillation patient demonstrating complete right bundle branch block

A 45-year-old male was admitted to our hospital after successful resuscitation of cardiac arrest. Ventricular fibrillation (VF) had occurred during breakfast and was defibrillated by an automated external defibrillator operated by emergency medical service staff. On admission, his ECG demonstrated complete right bundle branch block as the sole abnormality. Intensive examination could not detect any structural disease leading to a diagnosis of idiopathic VF and implantation of an ICD. VF storm occurred one month after hospital discharge and beta-blocker, amiodarone, and sedative administration had no effect on VF. Likewise, catheter ablation for triggering premature ventricular beats failed to control the VF storm. The VF storm then subsided in the following weeks and the patient was discharged on amiodarone. A half month later VF storm recurred and the patient was admitted again. This time, isoproterenol infusion was effective in suppressing VF, and thereafter the patient was administered bepridil and followed up without recurrence of VF for 1.5 years. From these beneficial effects, the VF of the patient was suggested to share common arrhythmogenic characteristics to those of Brugada syndrome or J-wave associated VF.

Idiopathic ventricular tachycardia cured by radiofrequency application from the distal great cardiac vein and the left coronary cusp

A 79 year-old male without structural heart disease suffered from drug refractory ventricular tachycardia (VT). VTs and premature ventricular complexes (PVCs) with the same morphology occurred incessantly with a concordant R pattern in chest leads and a tall R in Lead II, III, and aVF. The origin was expected to be near the left epicardial ventricular outflow tract (LVOT), which was termed the left ventricular summit area. Pace-mapping from the LVOT and the left coronary cusp (LCC) did not match well with the QRS morphology of the PVC. A good match was obtained from the distal great cardiac vein (GCV), and radiofrequency (RF) delivery eliminated the PVC and VT. However, the PVC recurred four times upon cessation of RF delivery. By placing an ablation catheter at the LCC, we obtained pace-mapping showing two different types of QRS morphologies; one was an rS pattern in V1, and the other was an R pattern in V1 with a longer stimulus to QRS interval, which was a nearly perfect match to the PVC. RF application to the LCC permanently eliminated PVCs and VTs. Several VTs from the epicardial LVOT can be cured by RF application from both the distal GCV and the LCC.

Ventricular fibrillation associated with complete right bundle branch block

BACKGROUND

A substantial number of patients with idiopathic ventricular fibrillation (IVF) present with no specific electrocardiographic (ECG) findings.

OBJECTIVE

To evaluate complete right bundle branch block (RBBB) in patients with IVF.

METHODS

Patients with IVF showing complete RBBB were included in the present study. Structural and primary electrical diseases were excluded, and provocation tests were performed to exclude the presence of spastic angina or Brugada syndrome (BrS). The prevalence of complete RBBB and the clinical and ECG parameters were compared either in patients with IVF who did not show RBBB or in the general population and age and sex comparable controls with RBBB.

RESULTS

Of 96 patients with IVF, 9 patients were excluded for the presence of BrS. Of 87 patients studied, 10 (11.5%) patients showed complete RBBB. None had structural heart diseases, BrS, or coronary spasms. The mean age was 44 ± 15 years, and 8 of 10 patients were men. Among the ECG parameters, only the QRS duration was different from that of the other patients with IVF who did not show complete RBBB. Ventricular fibrillation recurred in 3:2 in the form of storms, which were well suppressed by isoproterenol. Complete RBBB was found less often in control subjects (1.37%; P < .0001), and the QRS duration was more prolonged in patients with IVF: 139 ± 10ms vs 150 ± 14ms (P = .0061).

CONCLUSIONS

Complete RBBB exists more often in patients with IVF than in controls. A prolonged QRS complex suggests a conduction abnormality. Our findings warrant further investigation of the role of RBBB in the development of arrhythmias in patients with IVF.

Anatomical characteristics of the left atrial appendage in cardiogenic stroke with low CHADS2 scores

BACKGROUND

Strokes develop even in patients with low CHADS₂ scores, and the left atrial appendage (LAA) is the embolic source 90% of the time. We focused on the LAA morphology as a new predictor of strokes.

OBJECTIVE

To clarify the anatomical characteristics of the LAA for risk stratification of strokes in patients with nonvalvular atrial fibrillation (AF) who have low CHADS₂ scores.

METHODS

Among 80 patients who underwent catheter ablation of AF with contrast-enhanced computed tomography, the LAA characteristics were compared between 30 patients with histories of strokes and 50 age-matched controls. The LAA anatomy was classified into 4 types--"cactus," "cauliflower," "chicken wing," and "windsock"--discriminated by the computed tomography measurements of the length, angle, and number of lobes of the LAA.

RESULTS

The average CHADS₂ score did not differ significantly between patients with stroke and controls (0.8 ± 0.8 vs 0.6 ± 0.7; P = .277). Eight (26.7%) patients with stroke had CHA₂DS₂-VASc scores of 0. The left atrial size, LAA flow velocity, left ventricular function, and serum brain natriuretic peptide level were also unable to predict strokes. However, a "cauliflower" LAA, defined as a main lobe of less than 4 cm long without forked lobes, was significantly more common in patients with stroke (odds ratio 3.857; 95% confidence interval 1.482-10.037; P = .005). The CHA₂DS₂-VASc score-adjusted logistic regression analysis revealed the cauliflower LAA as an independent predictor of a stroke (odds ratio 3.355; 95% confidence interval 1.243-9.055; P = .017).

CONCLUSIONS

The LAA anatomy might be useful for predicting strokes in patients with nonvalvular AF who have low CHADS₂ scores.

The effectiveness of rigid pericardial endoscopy for minimally invasive minor surgeries: cell transplantation, epicardial pacemaker lead implantation, and epicardial ablation

Background

The efficacy and safety of rigid pericardial endoscopy as the promising minimally invasive approach to the pericardial space was evaluated. Techniques for cell transplantation, epicardial pacemaker lead implantation, and epicardial ablation were developed.

Methods

Two swine and 5 canines were studied to evaluate the safety and efficacy of rigid pericardial endoscopy. After a double pericardiocentesis, a transurethral rigid endoscope was inserted into the pericardial space. The technique to obtain a clear visual field was examined, and acute complications such as hemodynamic changes and the effects on intra-pericardial pressure were evaluated. Using custom-made needles, pacemaker leads, and forceps, the applications for cell transplantation, epicardial pacemaker lead implantation, and epicardial ablation were also evaluated.

Results

The use of air, the detention of a stiff guide wire in the pericardial space, and the stretching of the pericardium with the rigid endoscope were all useful to obtain a clear visual field. A side-lying position also aided observation of the posterior side of the heart. As a cell transplantation methodology, we developed an ultrasonography-guided needle, which allows for the safe visualization of transplantation without major complications. Pacemaker leads were safely and properly implanted, which provides a better outcome for cardiac resynchronizing therapy. Furthermore, the success of clear visualization of the pulmonary veins enabled us to perform epicardial ablation.

Conclusions

Rigid pericardial endoscopy holds promise as a safe method for minimally invasive cell transplantation, epicardial pacemaker lead implantation, and epicardial ablation by allowing clear visualization of the pericardial space.