Mark E. Alexander

Value of Programmed Ventricular Stimulation After Tetralogy of Fallot Repair A Multicenter Study

Background—Studies have consistently shown that ventricular tachycardia (VT) and sudden cardiac death (SCD) complicate the long-term outcome after tetralogy of Fallot repair, yet the diagnostic and predictive value of electrophysiological testing in this population is uncertain. Methods and Results—A multicenter cohort of 252 patients with repaired tetralogy of Fallot undergoing programmed ventricular stimulation was followed up for 18.5±9.6 and 6.5±4.5 years after corrective surgery and electrophysiological testing, respectively. Clinical VT and/or SCD occurred in 24.6%. Sustained monomorphic VT and polymorphic VT were induced in 30.2% and 4.4%. Including polymorphic VT in the definition of inducibility improved sensitivity (66.1±6.0% versus 77.4±5.3%, P = 0.0082) with a marginal reduction in specificity (81.6±2.8% versus 79.5±2.9%, P = 0.0455). Positive and negative predictive values were 55.2±5.3% and 91.5±2.2%. Independent risk factors for inducibility were age at study ≥18 years (OR, 3.3), palpitations (OR, 2.8), prior palliative surgery (OR, 3.1), modified Lown criteria ≥2 (OR, 5.6), and cardiothoracic ratio ≥0.6 (OR, 3.3). Event-free survival rates in noninducible and inducible patients at 1, 5, 10, and 15 years were 97.9%, 92.8%, 89.3%, and 89.3% versus 79.4%, 62.6%, 58.7%, and 50.3%, respectively (P < 0.0001). Both inducible monomorphic VT [relative risk (RR), 5.0; P = 0.0002] and polymorphic VT (RR, 12.9; P < 0.0001) predicted future clinical VT and SCD. In a multivariate analysis, inducible sustained VT was an independent risk factor for subsequent events (RR, 4.7; 95% CI, 1.2 to 18.5; P = 0.0268). Conclusions—Programmed ventricular stimulation is of diagnostic and prognostic value in risk stratifying patients with repaired tetralogy of Fallot. In this patient population, inducible sustained polymorphic VT should not be disregarded as nonspecific.

Results of a multicenter retrospective implantable cardioverter-defibrillator registry of pediatric and congenital heart disease patients.

OBJECTIVES We sought to determine the implications of implantable cardioverter-defibrillator (ICD) placement in children and patients with congenital heart disease (CHD). BACKGROUND There is increasing frequency of ICD use in pediatric and CHD patients. Until recently, prospective registry enrollment of ICD patients was not available, and children and CHD patients account for only a small percentage of ICD recipients. Therefore, we retrospectively obtained collaborative data from 4 pediatric centers, aiming to identify implant characteristics, shock frequency, and complications in this unique population. METHODS Databases from 4 centers were collated in a blinded fashion. Demographic information, implant electrical parameters, appropriate and inappropriate shock data, and complications were recorded for all implants from 1992 to 2004. RESULTS A total of 443 patients were included, with a median age of 16 years (range 0 to 54 years) and median weight of 61 kg (range 2 to 130 kg), with 69% having structural heart disease. The most common diagnoses were tetralogy of Fallot (19%) and hypertrophic cardiomyopathy (14%). Implant indication was primary prevention in 52%. Shock data were available on 409 patients, of whom 105 (26%) received appropriate shocks (mean 4 shocks/patient, range 1 to 29 shocks/patient). Inappropriate shocks occurred in 87 of 409 patients (21%), with a mean of 6 per patient (range 1 to 60), mainly attributable to lead failure (14%), sinus or atrial tachycardias (9%), and/or oversensing (4%). CONCLUSIONS Children and CHD ICD recipients have significant appropriate and inappropriate shock frequencies. Optimizing programming, medical management, and compliance may diminish inappropriate shocks. Despite concerns regarding generator recalls, lead failure remains the major cause of inappropriate shocks, complications, and system malfunction in children. Prospective assessment of ICD usage in this population may identify additional important factors in pediatric and CHD patients.

Influence of patient factors and ablative technologies on outcomes of radiofrequency ablation of intra-atrial re-entrant tachycardia in patients with congenital heart disease

OBJECTIVES The goal of this study was to identify factors associated with radiofrequency catheter ablation (RFCA) outcomes of intra-atrial re-entrant tachycardia (IART). BACKGROUND Radiofrequency catheter ablation of IART is difficult. The influence of patient and procedural factors and novel technologies on outcomes is unknown. METHODS Acute and chronic RFCA outcomes were studied in patients with congenital heart disease and IART. Clinical status was measured using a multiaxis severity score. Multivariate analyses identified associations of clinical, procedural and technological factors with outcomes. RESULTS A total of 177 procedures were performed in 134 patients; 139 procedures (79%) resulted in RFCA of > or =1 IART circuit and 117 (66%) in RFCA of all targeted circuits. Multivariate analysis associated acute success with irrigated ablation and absence of atrial fibrillation. Twenty-two complications were noted, nine related to vascular access. Electroanatomic mapping failed to decrease procedure or fluoroscopy time. Improvement in clinical status occurred in most patients (severity score preablation: 6.2 +/- 1.6, postablation: 3.0 +/- 2.3, p < 0.0001). At mean follow-up of 25 +/- 11 months, 42% of patients had IART recurrence and 28% required cardioversion. Six deaths occurred (1.8%/patient-year), and two patients underwent transplant. Chronic outcomes were associated with higher right atrial saturations, use of electroanatomic mapping, fewer IART circuits encountered and acute procedural success. CONCLUSIONS Improvement of acute RFCA outcomes was contemporaneous with introduction of novel technologies. Intra-atrial re-entrant tachycardia recurrence was common, and no effect on mortality was discerned, but most patients had effective palliation of symptoms. Chronic outcome predictors included the underlying disease severity, application of novel technologies and successful ablation of all targeted arrhythmia circuits.

Cardiac resynchronization therapy (and multisite pacing) in pediatrics and congenital heart disease: five years experience in a single institution.

Introduction: Clinical evidence supports the use of cardiac resynchronization therapy (CRT) in adults with heart failure, but experience in pediatrics and congenital heart disease (CHD) is limited in terms of patient numbers and follow‐up. We sought to determine the functional assessment and clinical outcomes in pediatric and CHD CRT patients followed uniformly at one institution.

Congestive heart failure hospitalizations and survival in California: patterns according to race/ethnicity.

BACKGROUND Congestive heart failure (CHF) disproportionately affects African Americans, but data are limited concerning CHF hospitalization patterns among Hispanic and Asian populations, the 2 fastest growing ethnic groups in the United States, and race/ethnic patterns of rehospitalization and survival among patients with CHF are unknown. We conducted a study to assess rates of CHF hospitalization, readmission, and survival among diverse populations in California. METHODS AND RESULTS We used 2 study designs. First, we calculated the population-based incidence of CHF hospitalization in California in 1991. Next we conducted a retrospective cohort study that identified patients initially hospitalized for CHF in 1991 or 1992 and followed these patients for 12 months after their index hospitalization to determine their likelihood of rehospitalization or death. Data were analyzed with Cox proportional hazards models. African Americans had the highest rate of CHF hospitalization. Age-adjusted hospitalization rates were comparable among whites, Latinos, and Asian women and all lower than those in African American, whereas Asian men had the lowest rates. On adjusted analyses, African Americans were more likely than whites and Asians to be rehospitalized (relative risk 1.07; 95% confidence interval 1.04 to 1.10). However, they were less likely to die within the 12-month follow-up period (relative risk 0.86; 95% confidence interval 0.82 to 0.90). Whites, conversely, had the highest posthospitalization mortality rates. CONCLUSIONS These findings demonstrate important racial-ethnic differences in CHF morbidity and mortality rates. The disparate findings of higher hospitalization and rehospitalization rates and lower mortality rates among African Americans than whites may represent differences in the underlying pathophysiology of CHF in these groups or differences in access to quality care. Further studies are needed to explain these seemingly paradoxical outcomes.

EHRA/HRS/APHRS expert consensus on ventricular arrhythmias.

Christian Torp Pedersen (EHRA Chairperson, Denmark), G. Neal Kay (HRS Chairperson, USA), Jonathan Kalman (APHRS Chairperson, Australia), Martin Borggrefe (Germany), Paolo Della-Bella (Italy), Timm Dickfeld (USA), Paul Dorian (Canada), Heikki Huikuri (Finland), Youg-Hoon Kim (Korea), Bradley Knight (USA), Francis Marchlinski (USA), David Ross (Australia), Frédéric Sacher (France), John Sapp (Canada), Kalyanam Shivkumar (USA), Kyoko Soejima (Japan), Hiroshi Tada (Japan), Mark E. Alexander (USA), John K. Triedman (USA), Takumi Yamada (USA), and Paulus Kirchhof (Germany)

Electroanatomic Mapping of Entrained and Exit Zones in Patients With Repaired Congenital Heart Disease and Intra-Atrial Reentrant Tachycardia

BackgroundCharacterization of reentrant circuits and targeting ablation sites remains difficult for intra-atrial reentrant tachycardias (IART) in congenital heart disease (CHD). Methods and ResultsElectroanatomic mapping and entrainment pacing were performed before successful ablation of 18 IART circuits in 15 patients with CHD. Principal features of IART circuits were atrial septal defect (4 patients), atriotomy (3 patients), other atrial scar (3 patients), crista terminalis (3 patients), and right atrioventricular valve (5 patients). A median of 176 sites (range, 96 to 317 sites) was mapped for activation and 13 sites (range, 9 to 28 sites) for entrainment response. Postpacing intervals within 20 ms of tachycardia cycle length and stimulus-to-P-wave intervals of 0 to 90 ms (exit zones) were mapped to atrial surfaces generated by electroanatomic mapping. Criteria for entrainment were met over a median of 21 cm2 of atrial surface (range, 2 to 75 cm2), 19% (range, 1% to 81%) of total area tested. Using integrated data, relations between activation sequence and protected corridor of conduction could be inferred for 16 of 17 IARTs. Successful ablation was achieved at a site distant from the putative protected corridor in 9 of 18 (50%) circuits. ConclusionsThe right atrium in CHD supports a variety of IART mechanisms. Fusion of activation and entrainment data provided insight into specific IART mechanisms relevant to ablation.

Value of Programmed Ventricular Stimulation in Patients with Congenital Heart Disease

Ventricular Stimulation in Congenital Heart Disease, introduction: The role of programmed ventricular stimulation (VSTIM) for risk stratification in congenital heart disease is unclear. We analyzed the results of VSTIM in selected congenital heart disease survivors at a single center lo determine whether it improved the ability to predict a serious outcome.

Efficacy of atrial antitachycardia pacing using the Medtronic AT500 pacemaker in patients with congenital heart disease.

Patients with congenital heart disease are vulnerable to atrial tachyarrhythmias, especially after atrial surgeries. We evaluated the efficacy of atrial arrhythmia detection and antitachycardia pacing (ATP) using the Medtronic AT500 pacemaker in 28 patients with congenital heart disease (age 30 +/- 18 years). Of 15 patients with atrial arrhythmias, 14 had atrial tachycardia events that were appropriately detected. ATP was enabled for 167 treatable episodes, successfully converting 90 (54%). Rhythms classified as ventricular tachycardia were detected 127 times, yet most were actually atrial or sinus tachycardia with 1:1 atrioventricular conduction. Atrial tachycardias in congenital heart disease are amenable to ATP algorithms in the AT500 pacemaker.

Age, Size, and Lead Factors Alone Do Not Predict Venous Obstruction in Children and Young Adults with Transvenous Lead Systems

Background: Venous occlusion is a recognized complication of transvenous pacing, and lead cross‐sectional area indexed to body surface area (BSA) has been used to predict venous obstruction in children.