Volker Menz

Repetitive monomorphic tachycardia from the left ventricular outflow tract : Electrocardiographic patterns consistent with a left ventricular site of origin

OBJECTIVES This study sought to characterize the electrocardiographic patterns predictive of left ventricular sites of origin of repetitive monomorphic ventricular tachycardia (RMVT). BACKGROUND RMVT typically arises from the right ventricular outflow tract (RVOT) in patients without structural heart disease. The incidence of left ventricular sites of origin in this syndrome is unknown. METHODS Detailed endocardial mapping of the RVOT was performed in 33 consecutive patients with RMVT during attempted radiofrequency ablation. Left ventricular mapping was also performed if pace maps obtained from the RVOT did not reproduce the configuration of the induced tachycardia. RESULTS Pace maps identical in configuration to the induced tachycardia were obtained from the RVOT in 29 of 33 patients. Application of radiofrequency energy at sites guided by pace mapping resulted in elimination of RMVT in 24 (83%) of 29 patients. In four patients (12%), pace maps obtained from the RVOT did not match the induced tachycardia. All four patients had a QRS configuration during RMVT with precordial R wave transitions at or before lead V2. In two patients, RMVT was mapped to the mediosuperior aspect of the mitral valve annulus, near the left fibrous trigone; catheter ablation at that site was successful in both. In two patients, RMVT was mapped to the basal aspect of the superior left ventricular septum. Catheter ablation was not attempted because His bundle deflections were recorded from this site during sinus rhythm. CONCLUSIONS RMVT can arise from the outflow tract of both the right and left ventricles. RMVTs with a precordial R wave transition at or before lead V2 are consistent with a left ventricular origin.

Programmed ventricular stimulation for arrhythmia risk prediction in patients with idiopathic dilated cardiomyopathy and nonsustained ventricular tachycardia

OBJECTIVES This study investigated the role of programmed ventricular stimulation (PVS) for arrhythmia risk prediction in patients with idiopathic dilated cardiomyopathy (IDC) and spontaneous nonsustained ventricular tachycardia (VT). BACKGROUND Nonsustained VT in patients with IDC has been associated with a high incidence of sudden cardiac death. METHODS Over the course of 4 years, 34 patients with IDC, a left ventricular (LV) ejection fraction < or = 35%, and spontaneous nonsustained VT underwent PVS. All patients were prospectively followed for 24+/-13 months. RESULTS Sustained ventricular arrhythmias were induced in 13 patients (38%). Sustained monomorphic VT was induced in three patients (9%), and polymorphic VT or ventricular fibrillation (VF) in another 10 patients (29%). No sustained ventricular arrhythmia could be induced in 21 study patients (62%). Prophylactic implantation of third-generation defibrillators (ICDs) with electrogram storage capability was performed in all 13 patients with inducible sustained VT or VF, and in nine of 21 patients (43%) without inducible sustained VT or VF. There were no significant differences between the additional use of amiodarone, d,I-sotalol, and beta-blocker therapy during follow-up in patients with and without inducible VT or VF. During 24+/-13 months of follow-up, arrhythmic events were observed in nine patients (26%) including sudden cardiac deaths in two patients and ICD shocks for rapid VT or VF in seven patients. Arrhythmic events during follow-up occurred in four of 13 patients with inducible ventricular arrhythmias compared with five of 21 patients without inducible ventricular arrhythmias at PVS (31% vs. 24%, p=NS). CONCLUSION PVS does not appear to be helpful for arrhythmia risk stratification in patients with IDC, a left ventricular ejection fraction < or =35%, and spontaneous nonsustained VT. Due to the limited number of patients, however, the power of this study is too small to exclude moderately large differences in outcome between patients with IDC with and without inducible VT or VF.

Electrophysiologic evaluation of sinus node function and atrioventricular conduction in patients with prolonged ventricular asystole during obstructive sleep apnea

In 15 patients with ventricular asystole of 8.5 +/- 3.5 seconds (range 5.0 to 16.8) occurring exclusively during obstructive sleep apnea, electrophysiologic study of sinus node function and atrioventricular conduction before and after administration of intravenous atropine (0.02 mg/kg) was performed. Electrophysiologic parameters of sinus node function were normal in 12 of 15 patients (80%) and atrioventricular (AV) nodal function was normal in 7 patients (47%). Almost all abnormal findings of sinus node function and AV nodal function were reversible by administration of atropine. The HisPurkinje system function was normal in 6 patients (40%). Prolonged HV intervals (57 to 73 ms) were found in 9 patients (60%). Intra- or infra-His block was not observed in any patient. In summary, electrophysiologic parameters of sinus node function and AV conduction were normal or only slightly abnormal in all 15 study patients, which suggests that prolonged ventricular asystole during obstructive sleep apnea is not due to fixed or anatomic disease of the sinus node or the AV conduction system.

Outcome of patients with sleep apnea–associated severe bradyarrhythmias after continuous positive airway pressure therapy

Twenty-nine patients in whom severe bradyarrhythmias occurred exclusively during obstructive sleep apnea and in whom advanced sinus node disease or atrioventricular conduction system dysfunction had been excluded by invasive electrophysiologic evaluation were prospectively followed on nasal continuous positive airway pressure. During 54 +/- 10 months follow-up, no syncope and no sudden deaths were observed, suggesting that patients with sleep apnea-associated bradyarrhythmias and a normal electrophysiologic study appear to have a favorable prognosis with continuous positive airway pressure.

Reversal of Tachycardia Induced Cardiomyopathy Following Ablation of Repetitive Monomorphic Right Ventricular Outflow Tract Tachycardia

GRIMM, W., et al.: Reversal of Tachycardia Induced Cardiomyopathy Following Ablation of Repetitive Monomorphic Right Ventricular Outflow Tract Tachycardia. Radiofrequency catheter ablation was performed in four adults with myocardial dysfunction related to repetitive monomorphic ventricular tachycardia (RMVT) originating in the right ventricular outflow tract. Serial echocardiographic assessment of left ventricular function before and after radiofrequency catheter ablation of RMVT showed complete reversal of left ventricular dysfunction without arrhythmia recurrence during 31 ± 28 months follow‐up.

Complications of Third-Generation Implantable Cardioverter Defibrillator Therapy

To determine the incidence of complications of third‐generation implantable cardioverter defibrillator (ICD) therapy, 144 patients were prospectively studied who underwent first implant of third‐generation devices (i.e., ICD systems with biphasic shocks, ECC storage capability, and nonthoracotomy lead systems). During 21 ± 15 months of follow‐up, 41 (28%) patients had one or more complications. No patient died perioperatively (30 days) and no ICD infection was observed during follow‐up. Complications included bleeding or pocket hematoma (hemoglobin drop > 2 g/dL) in 5 (3%) patients, prolonged reversible ischemic neurological deficit in 1 (1%) patient, postoperative deep venous thrombosis of leg in 1 (1%) patient, pneumothorax in 2 (1%) patients, difficulty to defibrillate ventricular fibrillation intraoperatively in 2 (1%) patients, generator malfunction in 1 (1%) patient, arthritis of the shoulder in 3 (2%) patients, and allergic reaction to prophylactic antibiotics in 2 (1%) patients. A total of seven lead related complications were observed in six (4%) patients including endocardial lead migration in four (3%) patients. Twenty‐three (16%) patients received inappropriate shocks for supraventricular tachyarrhythmias (n = 13), non‐sustained ventricular tachycardia (VT) (n = 7), or myopotential oversensing (n = 3). We conclude that serious complications such as perioperative death or ICD infection are rare in patients with third‐generation ICDs. Lead‐related problems and inappropriate shocks during follow‐up are the most frequent complications of third‐generation ICD therapy. Recognition of these complications should promote advances in ICD technology and management strategies to avoid their recurrence.

QT Dispersion and Arrhythmic Events in Idiopathic Dilated Cardiomyopathy

QT dispersion was measured in the 12-lead standard electrocardiogram in 107 patients with idiopathic dilated cardiomyopathy (IDC) and 100 age- and sex- matched controls without structural heart disease. All 107 study patients with IDC were prospectively followed in order to determine possible associations between QT dispersion and arrhythmic events, i.e., sustained ventricular tachycardia, ventricular fibrillation, or sudden death. QT dispersion, rate-corrected QT dispersion, and adjusted QTc dispersion, which takes account of the number of leads measured, were significantly greater in patients with IDC than in controls. During 13 +/- 7 months follow-up, arrhythmic events occurred in 12 of 107 study patients with IDC (11%). QT dispersion was increased in patients with versus without arrhythmic events during follow-up (76 +/- 17 vs 60 +/- 26 ms; p=0.03). QTc dispersion and adjusted QTc dispersion were not significantly different between patients with and without arrhythmic events (80 +/- 21 vs 75 +/- 35 ms, and 27 +/- 6 vs 24 +/- 10 ms, respectively). Thus, although QT dispersion was increased in patients with IDC and arrhythmic events during follow-up, its usefulness for arrhythmia risk prediction was limited by the large overlap of QT dispersion between patients with and without arrhythmic events.

Noninvasive Arrhythmia Risk Stratification in Idiopathic Dilated Cardiomyopathy: Design and First Results of the Marburg Cardiomyopathy Study

The Marburg Cardiomyopathy Study (MACAS) is a prospective, observational study designed to determine the value of the following potential noninvasive arrhythmia risk predictors in at least 200 patients with idiopathic dilated Cardiomyopathy (IDC) over a 5‐year follow‐up period: NYHA‐class, left ventricular ejection fraction (LVEF), left ventricular end‐diastolic diameter, left bundle branch block and atrial fibrillation on ECG, QT/JT dispersion on 12‐lead ECG, signal‐averaged ECG, ventricular arrhythmias and heart rate variability (HRV) on 24‐hour Hotter ECG, baroreflex sensitivity, and microvolt T wave alternans during exercise. This article describes the findings among the first 159 patients with IDCs enrolled in MACAS until May 1998 (40 women, 119 men;age:49 ± 12 years; LVEF: 32 ± 10%). Twenty‐nine patients (18%) had atrial fibrillation and 130 patients (82%) were in sinus rhythm. Patients with sinus rhythm were further stratified according to LVEF < 30% (n = 54) versus LVEF ≥ 50% (n = 76). Compared to patients with LVEF ≥ 30%, patients with LVEF < 30% more often had left bundle branch block (43% vs 25%, P < 0.05), nonsustained VT (44% vs 22%, P < 0.05), decreased HRV (SDNN: 95 ± 39 vs 128 ± 42 ms, P < 0.01), decreased baroreflex sensitivity (5.6 ± 4 vs 8.3 ± 6 ms/mmHg, P < 0.01), and T wave alternans (59% vs 37%, P < 0.05). The prognostic significance of these findings will be determined by multivariate Cox analysis at the end of a 5‐year follow‐up. Primary endpoints in MACAS are overall mortality and arrhythmic events (i.e., sustained VT or VF, or sudden cardiac death).

Heart rate variability and major arrhythmic events in patients with idiopathic dilated cardiomyopathy.

This prospective study of 71 patients with idiopathic dilated cardiomyopathy (IDC) and preserved sinus rhythm was designed to evaluate the relation between heart rate variability (HRV) and subsequent major arrhythmic events. Standard time‐ and frequency‐domain HRV parameters were obtained from analysis of 24‐hour Holter ECG recordings. During a mean follow‐up of 15 ± 5 months, major arrhythmic events including sustained ventricular tachycardia, ventricular fibrillation, and sudden cardiac death occurred in 10 of the 71 study patients (14%). Neither time‐ nor frequency‐domain indices of HRV differed significantly between patients with and patients without subsequent major arrhythmic events. However, there was a trend toward a lower standard deviation of the average normal RR interval for all 5‐minute segments of the 24‐hour recording (68 ± 17 ms vs 80 ± 31 ms; P = 0.06) in patients with major arrhythmic events. In addition, the percentage of adjacent normal RR intervals differing > 50 ms over the recording period tended to be lower in patients with major arrhythmic events (6%± 3% vs 9%± 6%; P = 0.08). Our results indicate a tendency toward attenuated parasympathetic activity in IDC patients with subsequent major arrhythmic events compared to arrhythmia‐free patients. Larger studies with longer follow‐up periods are necessary to clarify the role of HRV measurements for arrhythmia risk prediction in patients with IDC.

Clinical Significance of Increased QT Dispersion in the 12‐Lead Standard ECG for Arrhythmia Risk Prediction in Dilated Cardiomyopathy

QT dispersion was determined from the 12‐lead standard ECGs from 107 patients with idiopathic dilated Cardiomyopathy (IDC) and compared to QT dispersion measurements in 100 healthy age and sex matched controls. QT dispersion, rate corrected QT dispersion and adjusted QTC dispersion were significantly greater in patients with IDC compared to controls. During a prospective follow‐up of 13 ± 7 months, arrhythmic events, defined as sustained VT, VF, or sudden death, occurred in 12 (11%) of 107 study patients with IDC. QT dispersion was increased in patients with arrhythmic events compared to patients without arrhythmic events during follow‐up (76 ± 17 vs 60 ± 26 ms; P = 0.03). Differences in QTC dispersion and adjusted QTC dispersion between patients with and without arrhythmic events, however, failed to reach statistical significance. Thus, although QT dispersion was increased in patients with IDC and arrhythmic events during follow‐up, its clinical usefulness for risk stratification appears to be very limited due to the large overlap of QT dispersion among patients with and without arrhythmic events.