Sing-Chien Yap

Comparison of pregnancy outcomes in women with repaired versus unrepaired atrial septal defect

Objective  To compare the risks of complications during pregnancy in women with repaired and unrepaired atrial septal defects (ASDs) without associated complex cardiac lesions.

A Simplified Continuity Equation Approach to the Quantification of Stenotic Bicuspid Aortic Valves using Velocity-Encoded Cardiovascular Magnetic Resonance

OBJECTIVE We aimed to compare velocity-encoded cine cardiac magnetic resonance (CMR) with an established echocardiographic method for noninvasive measurement of aortic valve area (AVA) using the continuity equation. METHODS AND RESULTS Twenty consecutive young adults with stenotic bicuspid aortic valves were examined with CMR and transthoracic echocardiography (TTE). CMR AVA was calculated by the continuity equation, dividing stroke volume by the aortic velocity-time integral (VTIAorta), the stroke volume measured both by ventricular volume analysis and by phase contrast velocity mapping at 4 levels (1 subvalvar and 3 supravalvar). Stroke volumes measured at all levels correlated well with those from volumetric analysis. The CMR AVAs calculated using volumetric analysis and VTIAorta from jet velocity mapping correlated and agreed well with TTE AVA measurements (R2 = 0.83). When CMR AVA was calculated more rapidly using volume flow and VTIAorta both measured from the same trans-jet velocity acquisition, R2 was 0.74, with a bias and limits of agreement of 0.02 (-0.44, 0.47) cm2. CONCLUSIONS Continuity equation calculation of the AVA using CMR velocity mapping, with or without ventricular volumetric measurement, correlated and agreed well with the comparable and widely accepted TTE approach.

Longevity of implantable cardioverter defibrillators: a comparison among manufacturers and over time

Abstract Aims Longevity of implantable cardioverter defibrillators (ICDs) is crucial for patients and healthcare systems as replacements impact on infection rates and cost-effectiveness. Aim was to determine longevity using very large databases of two teaching hospitals with a high number of replacements and a rather homogeneous distribution among manufacturers. Methods and results The study population consists of all patients in whom an ICD was inserted in. All ICD manufacturers operating in Switzerland and the Netherlands and all implanted ICDs were included. Implantable cardioverter defibrillator replacements due to normal battery depletion were considered events, and other replacements were censored. Longevity was assessed depending on manufacturers, pacing mode, implant before/after 2006, and all parameters combined. We analysed data from 3436 patients in whom 4881 ICDs [44.2% VVI-ICDs, 27.4% DDD-ICDs, 26.3% cardiac resynchronization therapy (CRT)-ICDs, 2.0% subcutaneous ICDs] were implanted. The four major manufacturers had implant shares between 18.4 and 31.5%. Replacement due to battery depletion (27.4%) was performed for 1339 ICDs. Patient survival at 5 years was 80.1%. Longevity at 5 years improved in contemporary compared with elderly ICDs [63.9–80.6% across all ICDs, of 73.7–92.1% in VVIs, 58.2–76.1% in DDDs, and of 47.1–66.3% in CRT defibrillators, all P value < 0.05]. Remarkable differences were seen among manufacturers, and those with better performance in elderly ICDs were not those with better performance in contemporary ones. Conclusion Implantable cardioverter defibrillator longevity increased in contemporary models independent of manufacturer and pacing mode. Still, significant differences exist among manufacturers. These results might impact on device selection.

Evaluation of the need of elective implantable cardioverter-defibrillator generator replacement in primary prevention patients without prior appropriate ICD therapy

Objective It is not clear whether patients who received an implantable cardioverter-defibrillator (ICD) for primary prevention should undergo device replacement if they never experienced an appropriate ICD therapy during the first generator longevity. This study evaluated the incidence and predictors of appropriate ICD therapy after device replacement in this specific population. Methods From two large prospective ICD registries, we identified all primary prevention patients who had a first ICD replacement without previous appropriate ICD therapy. Cox regression analysis was used to identify predictors of appropriate ICD therapy. Results Of 403 primary prevention patients needing first ICD replacement, 275 patients (68%) had not received previous appropriate ICD therapy. Patients without previous appropriate ICD therapy before first ICD replacement (mean age at replacement 62±12 years, 75% male) had a mean follow-up of 86±24 months after the initial implantation and 30±24 months after device replacement. Following replacement, 3-year cumulative incidence of appropriate ICD therapy was 13.7% (95% CI 8.6 to 18.8%). No predictive factors associated with appropriate ICD therapy after replacement could be identified in spite of including seven clinically relevant factors. Conclusions A considerable number of primary prevention patients without previous appropriate ICD therapy before first ICD replacement received appropriate ICD therapy after replacement. As there were no predictors of appropriate ICD therapy after replacement, replacing an ICD is still recommended in all primary prevention patients despite the lack of appropriate ICD therapy during first battery service life.

Safety and Clinical Outcome of Catheter Ablation of Ventricular Arrhythmias Using Contact Force Sensing: Consecutive Case Series.

Poor catheter‐to‐myocardial contact can lead to ineffective ablation lesions and suboptimal outcome. Contact force (CF) sensing catheters in ventricular tachyarrhythmia (VT) ablations have not been studied for their long‐term efficacy.

Type and rate of atrial fibrillation termination due to rotational activity ablation combined with pulmonary vein isolation

There remains controversy about the optimal ablation technique and termination rate of atrial fibrillation (AF) during catheter ablation in patients with persistent AF. The aim of this study was to determine the rate and timing of AF termination during combined pulmonary vein isolation (PVI) and focal impulse and rotor modulation (FIRM)‐guided ablation of rotational activity (RoAc).

Complications of pacemaker therapy in adults with congenital heart disease: A multicenter study

BACKGROUND This study aims to investigate indications and complications of permanent cardiac pacing in adults with congenital heart disease (CHD). METHODS AND RESULTS Two-hundred and seventy-four CHD patients were identified who underwent permanent pacemaker implantation between 1972 and 2009. The indication for pacing was acquired sinus node or AV node conduction disease (63%), sinus node or AV node conduction disease after cardiac surgery (28%), and drug/arrhythmia-related indications (9%). Patients with complex CHD received a pacemaker at younger age (23 versus 31 years, p<0.0001) and more often received an epicardial pacing system (51% versus 23%, p<0.0001) compared to those with simple or moderate CHD. Twenty-nine patients (10.6%) had a periprocedural complication during the primary pacemaker implantation (general population: 5.2%). The most common acute complications were lead dysfunction (4.0%), bleeding (2.6%), pocket infection (1.5%) and pneumothorax (1.5%). During a median follow-up of 12 years, pacemaker-related complications requiring intervention occurred in 95 patients (34.6%). The most common late pacemaker-related complications included lead failure (24.8%), pacemaker dysfunction/early battery depletion (5.1%), pacemaker migration (4.7%) and erosion (4.7%). Pacemaker implantation at younger age (<18 years) was an independent predictor of late pacemaker-related complication (adjusted hazard ratio 1.68, 95% confidence interval 1.07 to 2.63, p=0.023). CONCLUSIONS The risk of periprocedural complications seems higher in the CHD population compared to the general population and more than one-third of CHD patients encountered a pacemaker-related complication during long-term follow-up. This risk increases for those who receive a pacemaker at younger age.

Recovery of Long-Axis Left Ventricular Function after Aortic Valve Replacement in Patients with Severe Aortic Stenosis

Background: Patients with aortic stenosis (AS) should undergo aortic valve replacement (AVR) before irreversible LV dysfunction has developed. Assessment of long‐axis left ventricular (LV) function may assist in proper timing of AVR. Objectives: To assess serial changes in long‐axis LV function before and after AVR in patients with severe AS and preserved LV ejection fraction. Methods: The study comprised 27 consecutive patients (mean age 64.9 ± 11.7 years, 15 males) with symptomatic severe AS, scheduled for AVR. Seventeen subjects without known cardiac disease, matched for age, gender, LV ejection fraction and cardiovascular risk factors, served as a control group. Long‐axis LV function assessment was done with tissue Doppler imaging at 3 weeks, 6 months, and 12 months after AVR. Results: Mean aortic valve area in the AS group was 0.70 ± 0.24 cm2. Pre‐AVR peak systolic mitral annular velocities were significantly lower compared to controls (6.7 ± 1.5 vs. 8.9 ± 2.0 cm/s, P < 0.05). Post‐AVR peak systolic mitral annular velocities improved to 9.1 ± 2.9 at 3 weeks, 8.6 ± 2.7 at 6 months, and 8.1 ± 1.7 cm/s at 12 months (P < 0.05). Improvements were seen over the whole range of pre‐AVR peak systolic mitral annular velocities. Patients with improved Sm after AVR (defined as ≥10% compared to baseline values) did not differ in baseline characteristics as compared to those who did not improve. Conclusions: In patients with severe AS and preserved LV ejection fraction, abnormal systolic mitral annular velocities improve after AVR, independent of the pre‐AVR value. (Echocardiography 2010;27:1177‐1181)

Air entrapment causing early inappropriate shocks in a patient with a subcutaneous cardioverter-defibrillator

The subcutaneous ICD (S-ICD) uses a different approach to sensing in comparison to conventional transvenous devices. A subcutaneous signal is used instead of an intracardiac signal. This may introduce new sensing issues as demonstrated by our case.

Atrial-based pacing has no benefit over ventricular pacing in preventing atrial arrhythmias in adults with congenital heart disease

AIMS To determine whether atrial-based pacing prevents atrial arrhythmias in adults with congenital heart disease (CHD) compared with ventricular pacing. METHODS AND RESULTS All adult CHD patients from four participating centres with a permanent pacemaker were identified. Patients with permanent atrial arrhythmias at pacemaker implantation and patients who received a pacemaker for treatment of drug-refractory atrial arrhythmias were excluded. The final study population consisted of 211 patients (52% male, 36% complex CHD) who received a first pacemaker for sick sinus dysfunction (n = 82) or atrioventricular block (n = 129) at a median age of 24 years [interquartile range (IQR), 12-34]. A history of atrial arrhythmias at implantation was present in 49 patients (23%). Atrial-based pacing was the initial pacing mode in 139 patients (66%) while the others (34%) received ventricular pacing. During a median follow-up of 13 years (IQR, 7-21), 90 patients (43%) developed an atrial arrhythmia. Multivariate analysis demonstrated no significant effect of atrial-based pacing on subsequent atrial arrhythmias [hazard ratio (HR), 1.53; 95% confidence interval (CI), 0.91-2.56; P = 0.1]. Independent predictors of atrial arrhythmia were history of atrial arrhythmias (HR, 5.55; 95% CI, 3.47-8.89; P< 0.0001), older age (≥18 years) at pacemaker implantation (HR, 2.29; 95% CI, 1.29-4.04; P = 0.005), and complex CHD (HR, 1.57; 95% CI, 1.01-2.45; P = 0.04). CONCLUSION In contrast to the general population, atrial-based pacing was not associated with a lower incidence of atrial arrhythmia in adults with CHD.