Electrophysiological characteristics of ventricular tachyarrhythmias in cardiac sarcoidosis versus arrhythmogenic right ventricular cardiomyopathy.

BACKGROUND: Recent evidence suggests that cardiac sarcoidosis (CS) and arrhythmogenic right ventricular cardiomyopathy (ARVC) can manifest very similarly. OBJECTIVE: To investigate whether there are significant demographic and electrophysiological differences between patients with CS and ARVC. METHODS: We prospectively compared patients with proven CS or ARVC who underwent radiofrequency catheter ablation of ventricular tachycardias by using 3-dimensional electroanatomical mapping. Furthermore, we evaluated whether the diagnostic criteria for ARVC would have excluded ARVC in patients with CS. RESULTS: Eighteen patients (13 men; mean age 44.9 years) were included. All 18 patients had mild to moderately reduced right ventricular ejection fraction. Patients with cardiac sarcoidosis (n = 8) had a significantly lower mean left ventricular ejection fraction (35.6±19.3 vs 60.6±9.4; P = .002). Patients with CS had a significantly wider QRS (0.146 vs 0.110s; P = .004). Five of 8 (63%) patients with CS fulfilled the diagnostic ARVC criteria. Ventricular tachycardias (VTs) with a left bundle branch block pattern were documented in all but one patient (with CS). Programmed ventricular stimulation induced an average of 3.7 different monomorphic VTs in patients with CS vs 1.8 in patients with ARVC (P = .01). VT significantly more often originated in the apical region of the right ventricle in CS vs ARVC (P = .001), with no other predilection sites. Ablation success and other electrophysiological parameters were not different. CONCLUSIONS: The current diagnostic ARVC guidelines do not reliably exclude patients with CS. Clinical and electrophysiological parameters that were characteristic of CS in our patients include reduced left ventricular ejection fraction, a significantly wider QRS, right-sided apical VT, and more inducible forms of monomorphic VT.

Prophylactic implantable defibrillator in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia and no prior ventricular fibrillation or sustained ventricular tachycardia.

BACKGROUND: The role of implantable cardioverter-defibrillator (ICD) in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia and no prior ventricular fibrillation (VF) or sustained ventricular tachycardia is an unsolved issue. METHODS AND RESULTS: We studied 106 consecutive patients (62 men and 44 women; age, 35.6±18 years) with arrhythmogenic right ventricular cardiomyopathy/dysplasia who received an ICD based on 1 or more arrhythmic risk factors such as syncope, nonsustained ventricular tachycardia, familial sudden death, and inducibility at programmed ventricular stimulation. During follow-up of 58±35 months, 25 patients (24%) had appropriate ICD interventions and 17 (16%) had shocks for life-threatening VF or ventricular flutter. At 48 months, the actual survival rate was 100% compared with the VF/ventricular flutter-free survival rate of 77% (log-rank P=0.01). Syncope significantly predicted any appropriate ICD interventions (hazard ratio, 2.94; 95% confidence interval, 1.83 to 4.67; P=0.013) and shocks for VF/ventricular flutter (hazard ratio, 3.16; 95% confidence interval, 1.39 to 5.63; P=0.005). The positive predictive value of programmed ventricular stimulation was 35% for any appropriate ICD intervention and 20% for shocks for VF/ventricular flutter, with a negative predictive value of 70% and 74%. None of the 27 asymptomatic patients with isolated familial sudden death had appropriate ICD therapy. Twenty patients (19%) had inappropriate ICD interventions, and 18 (17%) had device-related complications. CONCLUSIONS: One fourth of patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia and no prior sustained ventricular tachycardia or VF had appropriate ICD interventions. Syncope was an important predictor of life-saving ICD intervention and is an indication for ICD. Prophylactic ICD may not be indicated in asymptomatic patients because of their low arrhythmic risk regardless of familial sudden death and programmed ventricular stimulation findings. Programmed ventricular stimulation had a low predictive accuracy for ICD therapy.

Role of programmed ventricular stimulation in patients with Brugada syndrome: a meta-analysis of worldwide published data.

AIMS: Brugada syndrome (BS) is an ion channelopathy with the risk of sudden cardiac death. The role of programmed ventricular stimulation (PVS) in risk stratification has been controversially discussed. Therefore, we performed a meta-analysis on the prognostic role of PVS in BS. METHODS AND RESULTS: A Medline search until July 2006 documented 822 entries for BS. Only English publications with > 10 patients and a follow-up period were considered (n = 15). Patients [n = 1217; 974 males (80%)] were divided into three groups: survived sudden cardiac arrest (SCA) [n = 222 (18%)], syncope (Syncope) [n = 275 (23%)], and asymptomatic patients (Asympt) [n = 720 (59%)]. PVS was conducted in 1036 patients (85%). In 548 patients (53%), sustained ventricular tachyarrhythmias (VT) or ventricular fibrillation (VF) was inducible. During follow-up (34 +/- 40 months), VT/VF occurred in 141 patients. SCA bore the highest chance for a VT/VF occurrence during follow-up [odds ratio (OR) 14.4 compared with asymptomatic patients; P < 0.0005]. However, except for one study, the OR for VT/VF during follow-up in relation to VT/VF inducibility was non-significant (OR 1.5; P = ns). CONCLUSION: The main finding is that we were unable to identify a significant role of PVS with regard to arrhythmic events during follow-up in BS, thus questioning the role of PVS for risk stratification in patients with BS. Patients with BS and survived SCA show the highest chance for VT/VF occurrence during follow-up.

T wave alternans does not assess arrhythmic risk in patients with Brugada syndrome.

BACKGROUND: Brugada syndrome is associated with a risk for sudden death, but the arrhythmic risk in an individual Brugada syndrome patient is difficult to predict. Pathologic changes in the early repolarization phase of the ventricular action potential probably constitute part of the arrhythmogenic substrate in Brugada syndrome. Microvolt T wave alternans (TWA) assesses dynamic beat-to-beat changes in repolarization and has been suggested as a marker for repolarization-related sudden death. We therefore tested whether TWA is an indicator for arrhythmias in Brugada syndrome with a focus on right precordial ECG leads. METHODS: We assessed TWA in nine symptomatic, inducible patients with established Brugada syndrome and in seven healthy controls. TWA was assessed at rest and during exercise using both standard methods and an algorithm that assesses TWA in the early ST segment and the right precordial leads. RESULTS: None of the Brugada patients developed TWA in this study irrespective of analysis at rest or during exercise, neither using standard methods nor when the early ST segment was included in the analysis. When the early ST segment was included in the analysis, nonsustained TWA was found in three out of seven, and sustained TWA in one control. CONCLUSION: T wave alternans is not an appropriate test to detect arrhythmic risk in patients with Brugada syndrome.

Chronic electrical stimulation during the absolute refractory period of the myocardium improves severe heart failure.

AIM: In experimental studies, nonexcitatory electrical stimulation delivered at the time of absolute myocardial refractoriness resulted in cardiac contractility modulation (CCM) with improved systolic function. This study reports the initial experience with CCM in patients with chronic heart failure. METHODS AND RESULTS: Twenty-five patients, 23 males, with a mean age of 62+/-9 years and drug-refractory NYHA class III heart failure were assigned to CCM-generator implantation. The underlying heart disease was idiopathic dilated cardiomyopathy in 12 patients and coronary heart disease in 13 patients. Acute efficacy of CCM with 7.73-V stimuli delivered via two right ventricular leads was evaluated by measuring the time derivative of left ventricular pressure (dP/dt). After implantation, the CCM generator was activated for 3 h daily over 8 weeks. In 23/25 patients the CCM system was implanted successfully. Heart failure significantly improved from NYHA class III to class II in 15 patients and to class I in 4 patients (p < 0.000001), left ventricular ejection fraction improved from 22+/-7% to 28+/-8% (p = 0.0002), and the Minnesota Living with Heart Failure Score improved from 43+/-22 to 25+/-18 (p = 0.001). The 6-min walk test increased from 411+/-86 to 465+/-81 m (p= 0.02). Nine patients (39%) had intermittent sensations associated with CCM delivery. There were two (8%) non-device-related deaths during follow-up. CONCLUSIONS: These preliminary data indicate that CCM by delivery of intermittent nonexcitatory electrical stimuli is a promising technique for improving ventricular systolic function and symptoms in patients with drug-refractory NYHA class III heart failure.

Body surface area of ST elevation and the presence of late potentials correlate to the inducibility of ventricular tachyarrhythmias in Brugada syndrome.

INTRODUCTION: The value of noninvasive markers reflecting repolarization and/or conduction abnormalities in identifying patients with abnormal ECG showing a pattern of atypical right bundle branch block and ST elevation syndrome (Brugada syndrome) at risk for life-threatening arrhythmias is controversial. Because right precordial ST elevation reflects inhomogeneous repolarization, we hypothesized that a correlation between the area of ST elevation, that is, the area of inhomogeneous repolarization, and the inducibility of ventricular tachyarrhythmias (VT) exists. Therefore, the body surface area of ST elevation and the presence of late potentials were compared to the inducibility of VT in patients with the characteristic ECG of Brugada syndrome. METHODS AND RESULTS: A 120-channel body surface potential map was recorded at rest and after administration of a Class I agent (ajmaline, 1 mg/kg) to measure the body surface area of ST elevation (> or = 0.2 mV) in 23 individuals (16 patients had been resuscitated from near sudden cardiac death or had suffered syncope) with an ECG compatible with the diagnosis of Brugada syndrome as well as in 15 healthy controls and in 15 patients with arrhythmogenic right ventricular cardiomyopathy. Late potentials were assessed in 20 of the Brugada patients using signal-averaged ECG. Programmed ventricular stimulation was performed at two ventricular sites with up to three extrastimuli. Mean body surface area of ST elevation (> or = 0.2 mV) of all Brugada syndrome patients was 154 +/- 139 cm2 (control 9 +/- 9 cm2; P < 0.001). In the group of patients with arrhythmogenic right ventricular cardiomyopathy, only one patient was found to have an area of ST elevation (165 cm2). In the presence of ajmaline, area size increased to 330 +/- 223 cm2 in Brugada syndrome patients (P < 0.05). In patients with inducible sustained (n = 15) and nonsustained VT (n = 3), a mean area of 183 +/- 139 cm2 was found, whereas the area was only 52 +/- 58 cm2 in those with no VT induction (P < 0.05). For an area > or = 50 cm2, there were positive and negative predictive values of 92% and 60%, respectively. Positive late potentials were found in 60% of patients and correlated to the inducibility during programmed ventricular stimulation (positive predictive value 100%, negative predictive value 75%; P < 0.001). CONCLUSION: In patients with Brugada syndrome, the body surface area of ST elevation and the presence of late potentials correlate to the inducibility of VT during programmed ventricular stimulation and may be of value as a new noninvasive marker for risk stratification in these patients.