Satoshi Kawada

Comparison of longevity and clinical outcomes of implantable cardioverter-defibrillator leads among manufacturers

BACKGROUND An early failure of the Biotronik Linox S/SD implantable cardioverter-defibrillator (ICD) lead has been reported. We have also experienced several cases with early failure of Linox leads. OBJECTIVE Our aim was to assess the longevity of Linox S/SD (Biotronik, Berlin, Germany) compared with Sprint Fidelis (Medtronic, Minneapolis, MN), Sprint Quattro (Medtronic), and Endotak Reliance (Boston Scientific, Natick, Massachusetts) leads. METHODS We retrospectively reviewed patients who had undergone implantation of Linox S/SD (n = 90), Sprint Fidelis (n = 37), Sprint Quattro (n = 27), or Endotak Reliance (n = 50) leads between June 2000 and December 2013 at our hospital. Variables associated with lead failure were assessed by the Kaplan-Meier method and Cox survival modeling. RESULTS Failure rates of Linox, Sprint Fidelis, and Endotak leads were 3.2%/year (7-year survival rate, 81.0%), 3.4%/year (7-year survival rate, 77.2%), and 0.61%/year (7-year survival rate, 95.8%), respectively. No lead failure was found with Sprint Quattro leads. The survival probability of Linox leads was significantly lower than that of Endotak leads (P = .049) and comparable to that of Sprint Fidelis leads (P = .69). In univariate analysis, age was the only predictor of Linox lead failure. Patients <58 years old were at significantly increased risk of lead failure compared with patients ≥58 years old (hazard ratio, 9.0; 95% confidence interval, 1.13-71.3; P = .037). CONCLUSION In our single-center experience, the survival rate of Linox leads was unacceptably low. The only predictor of Linox lead failure was age at implantation. This is the first description of a lower survival rate for Linox leads in an Asian population.

Distribution and prognostic significance of fragmented QRS in patients with brugada syndrome

Background— Fragmented QRS complexes (fQRS) in the right precordial leads are associated with occurrence of ventricular fibrillation (VF) in Brugada syndrome. Recently, epicardial mapping has revealed abnormal electrograms at the right ventricular (RV) outflow tract and inferior region of the right ventricle. fQRS may reflect the extent of the area of abnormal potentials, but whether the distribution of fQRS has prognostic value is not known. Methods and Results— We evaluated the existence of fQRS in 456 patients with Brugada syndrome, including 117 patients with syncope and 23 patients with VF. The region of fQRS was defined as inferior (II, III, and aVF), lateral (I, aVL, and V5 and V6), anterior (V3 and V4), RV (V1 and V2), and RV outflow tract (V1 and V2 at the third intercostal space). fQRS were present in 229 patients (RV outflow tract in 175, inferior in 135, RV in 90, and lateral in 16 patients). During follow-up (mean 91 months), 39 patients experienced VF. In univariable analyses, fQRS in any distribution and fQRS in each region excluding the RV were associated with VF. Multivariable analysis showed that fQRS in the inferior (hazard ratio, 3.9; confidence interval, 1.9–8.5), lateral (hazard ratio, 3.5; confidence interval, 1.2–8.2), and RV outflow tract (hazard ratio, 2.5; confidence interval, 1.2–5.6) were associated with VF events. The presence of multiple regions of fQRS was associated with worse prognosis. Conclusions— The distribution of fQRS is associated with prognosis in Brugada syndrome, further supporting the association of fQRS and arrhythmia substrate.

Identification of electrocardiographic risk markers for the initial and recurrent episodes of ventricular fibrillation in patients with Brugada syndrome

New onset of ventricular fibrillation (VF) in asymptomatic patients with Brugada‐type ECG is not frequent, but it cannot be negligible. Risk markers for predicting VF are usually based on results of analysis in symptomatic patients, and they have not been determined for asymptomatic patients. We analyzed ECG markers in patients with Brugada syndrome to differentiate the risk factors for VF in both symptomatic and asymptomatic patients.

Progression of electrocardiographic abnormalities associated with initial ventricular fibrillation in asymptomatic patients with Brugada syndrome

BACKGROUND Various risk stratifications in asymptomatic patients with Brugada syndrome (BrS) have been proposed, but the electrophysiological change that promotes ventricular fibrillation (VF) is still unknown. OBJECTIVE The aim of this study was to clarify the changes in electrocardiographic (ECG) markers at the onset of VF from ECGs recorded when patients were still asymptomatic. METHODS The subjects of this study included 14 patients with VF and 48 consecutive asymptomatic patients with BrS. We compared ECGs before the initial VF events (>6 months; early phase) with ECGs at the initial VF events (late phase). In asymptomatic patients, we evaluated ECGs at 2 time points with an interval of >6 months. We evaluated various ECG markers including type 1 ECG and fragmented QRS (fQRS; multiple spikes within the QRS complex). RESULTS ECG parameters of the early and late phases were not different except for decreased ST voltage and low incidence of type 1 ECG in asymptomatic patients. There were no differences in ECG parameters of the early phase between patients with VF and asymptomatic patients. In patients with VF, ECGs at the late phase had longer QRS intervals and intervals between the peak and the end of the T wave and more frequent type 1 ECG and fQRS than did ECGs at the early phase. Those changes were associated with initial VF events (QRS widening: odds ratio [OR] 11.5, P < .01; interval between the peak and the end of the T wave: OR 11.6, P < .01; fQRS: odds ratio 15.3, P < .01; type 1 ECG: OR 6.6, P < .05). CONCLUSION QRS and ST-T wave abnormalities developed in association with the initial VF events. Aggravation of the conduction disturbance in addition to BrS-ECG promotes VF.

Prognostic Significance of the Sodium Channel Blocker Test in Patients With Brugada Syndrome

Background A drug provocation test using a sodium channel blocker (SCB) can unmask a type 1 ECG pattern in patients with Brugada syndrome. However, the prognostic value of the results of an SCB challenge is limited in patients with non–type 1 ECG. We investigated the associations of future risk for ventricular fibrillation with SCB‐induced ECG changes and ventricular tachyarrhythmias (VTAs). Methods and Results We administered intravenous pilsicainide to 245 consecutive patients with Brugada syndrome (181 patients with spontaneous type 1 ECG, 64 patients with non–type 1 ECG). ECG parameters before and after the test and occurrence of drug‐induced VTAs were evaluated. During a mean follow‐up period of 113±57 months, fatal VTA events occurred in 31 patients (sudden death: n=3, ventricular tachycardia/ventricular fibrillation: n=28). Symptomatic patients and spontaneous type 1 ECG were associated with future fatal arrhythmic events. Univariable analysis of ECG parameters after the test showed that long PQ and QRS intervals, high ST level, and SCB‐induced VTAs were associated with later VTA events during follow‐up. Multivariable analysis showed that symptomatic patients, high ST level (V1) ≥0.3 mV after the test, and SCB‐induced VTAs were independent predictors for future fatal arrhythmic events (hazard ratios: 3.28, 2.80, and 3.62, 95% confidence intervals: 1.54–7.47, 1.32–6.35, and 1.64–7.75, respectively; P<0.05). Conclusions SCB‐induced VTAs and ST‐segment augmentation are associated with an increased risk of the development of ventricular tachycardia/ventricular fibrillation events during follow‐up in patients with Brugada syndrome.

Impact of Chronic Kidney Disease on Cardiovascular and Renal Events in Patients Undergoing Percutaneous Coronary Intervention with Everolimus-Eluting Stent: Risk Stratification with C-Reactive Protein

Background: Chronic kidney disease (CKD) and inflammation play critical roles in atherosclerosis. There is limited evidence regarding the relationship between CKD and patients receiving second-generation drug-eluting stents for coronary artery disease. Objective: This study aimed to investigate the effect of CKD on cardiovascular and renal events in patients undergoing percutaneous coronary intervention (PCI) with everolimus-eluting stents (EES). Methods: We analyzed 504 consecutive patients with stable angina pectoris and significant coronary artery stenosis treated with EES. CKD was defined as an estimated glomerular filtration rate < 60 mL/min/1.73 m2 before coronary angiography. The primary outcome was the occurrence of major adverse renal and cardiovascular events (MARCE) including cardiac death, revascularization, heart failure, cerebral infarction, worsening renal function > 25% from baseline, and renal replacement therapy at 1 year. Results: Patients were divided into the a MARCE (n = 126) and a non-MARCE (n = 378) group. The incidence of CKD was 51% in all subjects (including those on hemodialysis) and was significantly higher in the MARCE group than in the non-MARCE group (p = 0.00001). Multivariate logistic regression analysis identified that CKD was independently associated with MARCE (adjusted odds ratio 2.03, 95% confidence interval 1.21–3.39, p = 0.007). Patients were divided into four groups based on CKD and C-reactive protein (CRP) level prior to initial coronary angiography. Cox proportional hazards analysis revealed that patients with CKD and high CRP (≥0.3 mg/dL) had the worst prognosis (hazard ratio 4.371, 95% confidence interval 2.634–7.252, p = 0.00001) compared to patients without CKD and with low CRP. Conclusion: CKD combined with CRP predicted more clinical events in patients undergoing PCI with EES.

Complete right bundle branch block and QRS-T discordance can be the initial clue to detect S-ICD ineligibility

BACKGROUND In order to minimize inappropriate shocks of subcutaneous implantable cardioverter-defibrillators (S-ICD), it is important to recognize who is suitable for S-ICD indication. This study aimed to clarify what types of cardiac disease are likely to fulfill the S-ICD screening criteria and ineligible factors for S-ICD in the standard 12-lead electrocardiogram (ECG). METHODS A total of 348 patients with heart disease were enrolled. They were assessed by supine and standing ECG recording to simulate the 3 S-ICD sensing vectors and standard 12-lead ECG, simultaneously. Clinical and ECG characteristics were analyzed to compare the patients who are eligible and ineligible with S-ICD screening ECG indication. RESULTS The mean age of study patients was 49±21 years and 244 (70%) were men. Nineteen percent of patients were unsuitable for S-ICD. There was no significant difference in ineligibility for S-ICD among cardiac diseases (p=0.48). Univariate analysis showed complete right bundle branch block (CRBBB), QRS-T discordance in lead II, and QRS-T discordance in 3 leads (I, II, and aVF) were more frequent in patients who were ineligible for S-ICD than in the eligible group. Multivariate regression analysis showed CRBBB and QRS-T discordance in 3 leads were independent predictors for ineligibility of S-ICD. CONCLUSION There are no differences in eligibility of S-ICD among types of cardiac diseases. CRBBB and QRS-T discordance were independent predictors for ineligibility.

Initial experience with the subcutaneous implantable cardioverter-defibrillator in a single Japanese center

The subcutaneous implantable cardioverter‐defibrillator (S‐ICD) is recognized as a viable alternative to the transvenous ICD. The safety and efficacy of this device has been demonstrated in Western countries, but studies with S‐ICD implantation in Japanese patients have not been reported.

Analysis of arrhythmic events is useful to detect lead failure earlier in patients followed by remote monitoring

Remote monitoring (RM) has been advocated as the new standard of care for patients with cardiovascular implantable electronic devices (CIEDs). RM has allowed the early detection of adverse clinical events, such as arrhythmia, lead failure, and battery depletion. However, lead failure was often identified only by arrhythmic events, but not impedance abnormalities.

Catheter ablation of three macroreentrant atrial tachycardias after surgical repair of Double-Outlet Right Ventricle

A 54‐year‐old man with a surgically repaired double‐outlet right ventricle (DORV) presented with palpitations and worsening right heart failure. His 12‐lead ECG showed atrial tachycardia (AT) with an atrial cycle length (CL) of 300 ms and an inverted saw‐tooth F‐wave pattern in the inferior leads II, III, and aVF typical of atrial flutter. Electrophysiological study and radiofrequency catheter ablation were performed. A total of 3 sustained ATs (AT1–AT3) were induced. Using the electroanatomical mapping system, CARTO3, and conventional mapping techniques, the ATs were identified as macroreentrant tachycardias circling around an incisional line on the free wall of the right atrium (AT1), the tricuspid annulus (AT2), and low voltage area in the lateral wall including the right septum (AT3). Accuracy of CARTO3 in three‐dimensional reconstruction was sufficient to elucidate anatomical features (including catheter sites, incision, and low voltage areas) and macroreentrant circuits. However, conventional mapping techniques were also necessary to identify the mechanism of the tachycardias, and therefore to eliminate all of them successfully. This case demonstrates that the use of combined conventional and electroanatomical mapping techniques, such as CARTO3, can be helpful in identifying the critical isthmus for catheter ablation of macroreentrant AT in patients with surgically corrected congenital heart disease (CHD).