Thomas Pezawas

Implantable Loop Recorder in Unexplained Syncope: Classification, Mechanism, Transient Loss of Consciousness and Role of Major Depressive Disorder in Patients with and without Structural Heart Disease

Objective: To stratify mechanisms and predictors of unexplained syncope documented by an implantable loop recorder (ILR) in patients with and without structural heart disease (SHD). Design and setting: Prospective study in consecutive patients of a university cardiac centre. Patients and methods: An ILR was implanted in 70 patients (34 male/36 female, aged 55 (17) years) in whom syncope remained unexplained after thorough testing. SHD was present in 33 patients (ischaemic cardiomyopathy in 16, dilated cardiomyopathy in 9 and hypertrophic cardiomyopathy in 8) and absent in 37 patients (mean (SD) left ventricular ejection fraction 46 (4)% vs 61 (7)%, respectively). Results: A syncopal recurrence occurred during 16 (8) months in 30 patients (91%) with SHD and in 30 patients (81%) without SHD. Fifteen patients (45%) versus 19 patients (51%), respectively, had an ILR-documented arrhythmia at the time of recurrence which led to specific treatment. The remaining 15 patients (45%) with SHD and 11 patients (30%) without SHD had normal sinus rhythm at the time of the recurrence. On stepwise multivariate analysis only major depressive disorder was predictive for early recurrence during ILR follow-up (p = 0.01, hazard ratio  =  3.35, 95% CI 1.1 to 7.1). Fifty seven per cent of patients with major depressive disorder had sinus rhythm during recurrence compared with 31% of patients without the disorder (p = 0.01). Conversely, no patient with major depressive disorder had asystole compared with 33% without (p<0.001). Conclusions: The presence of SHD has little predictive value for the occurrence or type of arrhythmia in patients with unexplained syncope. Patients with major depressive disorder are prone to early recurrence of symptoms and have no evidence of arrhythmia in most cases. The ILR leads to specific treatment in half of all patients.

Electromagnetic interference by transcutaneous neuromuscular electrical stimulation in patients with bipolar sensing implantable cardioverter defibrillators: a pilot safety study.

CREVENNA, R., et al.: Electromagnetic Interference by Transcutaneous Neuromuscular Electrical Stimulation in Patients with Bipolar Sensing Implantable Cardioverter Defibrillators: A Pilot Safety Study. Neuromuscular electrical stimulation (NMES) is a frequently applied therapy for the treatment of pain and a therapeutic option to increase thigh muscle strength and endurance capacity in patients with heart failure. Electromagnetic interference (EMI) by the signals with sensing of ICDs is possible. Eight patients with subpectoral ICD systems and different transvenous bipolar sensing leads were subjected to electrical stimulation of the neck and shoulder and of the thighs using different stimulation algorithms. EMI with ventricular sensing was detectable in three of eight subjects. EMI occurred during stimulation of the neck (n = 2) and thigh (n = 2). EMI by NMES with atrial sensing was seen in two of four subjects with dual chamber ICDs. The safety of peripheral NMES has to be individually tested as EMI can also occur in ICD patients with bipolar sensing. (PACE 2003; 26[Pt. I]:626–629)

Impact of accelerated ventricular tachyarrhythmias on mortality in patients with implantable cardioverter-defibrillator therapy

BACKGROUND Anti-tachycardia pacing (ATP) and shock delivery may induce or accelerate tachyarrhythmias in patients with implantable cardioverter-defibrillator (ICD). We investigated the incidence, triggers and impact on mortality of accelerated ventricular tachyarrhythmias. METHODS Database analysis concerning ventricular tachyarrhythmias accelerated by ATP or shock in 1275 ICD patients (age at implantation 59.7 ± 14.0 years; 81% male). RESULTS Within a mean follow-up period of 5.3 ± 4.0 years, intracardiac electrograms were available in 1170 patients (91.8%). Overall 157 episodes of accelerated ventricular tachyarrhythmias were found in 100 of 1170 patients (8.5%). Termination of tachyarrhythmias was achieved by shock delivery in 153 episodes (96.8%). Triggers of accelerated tachyarrhythmias were appropriate ATP in 139 (88.5%) and inappropriate ATP in 14 (8.9%), as well as appropriate and inappropriate shocks in 2 (1.3%) episodes, respectively. Chronic heart failure was significantly correlated with the occurrence and recurrence of acceleration (p<0.001). Patients with accelerated ventricular tachyarrhythmia and subsequent shock therapy revealed higher all-cause mortality (HR 1.760; 95% CI 1.286-2.410; p<0.001) as well as higher cardiac mortality (HR 2.555; 95% CI 1.446-4.513; p=0.001). The correlation between acceleration and all-cause mortality was independent of left ventricular function (HR 2.076; 95% CI 1.633-2.639; p<0.001). CONCLUSIONS Ventricular ATP with arrhythmia acceleration and subsequent shock delivery is a frequent and serious complication of ICD therapy that predominantly occurs in patients with reduced left ventricular function. Finally, occurrence of accelerated ventricular tachyarrhythmias was associated with increased all-cause mortality.

Regional prevalence and clinical benefit of implantable cardioverter defibrillators in Brugada syndrome

BACKGROUND Brugada syndrome (BS) is associated with an increased risk of sudden cardiac death (SCD) caused by ventricular tachyarrhythmia. Thus, implantable cardioverter defibrillators (ICD) became the main therapeutic option in these patients. We aimed to investigate the prevalence of BS in the Eastern Alps as well as the benefit of ICD therapy in this collective. METHODS During physical examination before military service, 47,606 Austrian men were screened for Brugada ECG pattern. Furthermore, we followed 4491 patients with arrhythmia during the last two decades, of which 26 patients (20 male; age at diagnosis: 43.2 ± 11.6 years) revealed BS. Diagnosis was based on characteristic ECG either at rest (11 patients) or after provocation with Ajmaline (15 patients). RESULTS The nationwide screening revealed one individual with Brugada ECG (prevalence of 2.10/100,000 inhabitants). Prior to diagnosis of BS, syncope and SCD survival were observed in 7 and 4 patients, respectively; the remaining 15 patients were asymptomatic. ICD were implanted in 17 patients (15 male). Three asymptomatic patients received no ICD because no tachyarrhythmia was inducible on programmed stimulation. Six asymptomatic patients without family history of sudden death refused further evaluation. Mean ICD follow-up period was 57.0 ± 32.2 months. Two patients (11.7%) needed defibrillation therapy. Four patients (23.5%) received exclusively inappropriate shocks (three due to T-wave oversensing, one due to atrial fibrillation). CONCLUSIONS Brugada syndrome has a low prevalence in the Eastern alpine region. Patients with BS benefit from ICD implantation, but less frequently than anticipated. The problem of inappropriate ICD discharges is still of major concern.

Single, remote-magnetic catheter approach for pulmonary vein isolation in patients with paroxysmal and non-paroxysmal atrial fibrillation.

BACKGROUND The aim of the study was to investigate the safety and efficacy of a single, remote-magnetic catheter navigation system (MNS) for pulmonary vein isolation (PVI). METHODS A total of 107 PVI procedures in 71 patients with paroxysmal (32%), persistent (38%) and longstanding-persistent (30%) atrial fibrillation (AF) were analyzed. A wide area circumferential radiofrequency ablation PVI was performed with either an 8mm MNS (first 35 procedures) or an irrigated MNS (last 36 procedures) catheter. Electrical isolation was confirmed with circular pacing/sensing using the MNS catheter and a coronary sinus catheter. Our follow-up strategy in the first year and upon symptoms thereafter was: clinical check plus 12-lead ECG (100%) and 24 h-ECG recordings (76%) at 3 month intervals, trans-telephonic ECG (79%) twice daily and upon symptoms (4 weeks every 3 months), or ECG monitoring via implanted devices (9%). RESULTS The mean procedure time at 1st PVI was 247±61 min, and mean fluoroscopy time was 44±18 min. The overall complication rate was 2%. Success rates did not differ at the 1st PVI regarding catheter type (p=0.931) but were dependent on history of AF: patients with paroxysmal AF had the highest success rates of 58% and 29% after 1 and 3 years of follow-up, respectively (p=0.0084). CONCLUSION PVI with a single MNS catheter is safe and is associated with short fluoroscopy exposition. Despite a rigorous follow-up strategy success rates favorably compare with recently published data on hand-held PVI. Thus, multipolar catheters or a 2nd trans-septal puncture may not be mandatory.

Multiple autonomic and repolarization investigation of sudden cardiac death in dilated cardiomyopathy and controls.

Background—Prophylactic defibrillator implantation is recommended in dilated, nonischemic heart disease and left ventricular ejection fraction of ⩽0.30 to 0.35. Noninvasive testing should improve accuracy in decision making of prophylactic defibrillator implantation. Methods and Results—We enrolled 60 patients (median age, 57 years) with dilated cardiomyopathy and left ventricular ejection fraction ⩽0.50, and 30 control subjects (median age, 59 years) with left ventricular ejection fraction >0.50. The protocol included an initial assessment, a second assessment after 3 years, and a final follow-up: pharmacological baroreflex testing (baroreceptor reflex sensitivity), short-term spectral analysis of heart rate variability (low frequency/high frequency), and long-term time domain analysis (SD of all normal-to-normal R–R intervals), exercise microvolt T wave alternans, and signal-averaged ECG, and corrected QT-time. The median follow-up was 7 years. End points were cardiac death, resuscitated cardiac arrest, and arrhythmic death. Cardiac death was observed in 21 patients. Resuscitated cardiac arrest and arrhythmic death caused by ventricular tachyarrhythmias ≥240 per minute was observed in 7 and 10 patients, respectively. In the single time point analysis, microvolt T wave alternans, baroreceptor reflex sensitivity, and SD of all normal-to-normal R–R intervals at initial testing added significant information regarding cardiac death. Microvolt T wave alternans added information on resuscitated cardiac arrest or arrhythmic death at multiple time points (P<0.001). False-negative microvolt T wave alternans results were seen in 8% of patients. Conclusions—Noninvasive testing and left ventricular ejection fraction could not reliably identify patients with dilated cardiomyopathy at risk of fatal ventricular tachyarrhythmias. Therefore, the strategy to confine prophylactic implantable cardioverter-defibrillator implantation to patients with dilated cardiomyopathy and severely reduced LV function should be reconsidered.

Primary preventive cardioverter-defibrillator implantation (Pro-ICD) in patients awaiting heart transplantation. A prospective, randomized, controlled 12-year follow-up study

The aim of this study was to evaluate whether short‐term primary preventive cardioverter‐defibrillator (ICD) implantation as bridge to heart transplantation (HTX) provides any survival benefit. Thirty‐three patients awaiting HTX were randomized to either conventional therapy (control group) or primary preventive ICD implantation (ICD group). Fourteen patients had ischemic cardiomyopathy (ICM) and 19 patients had dilated cardiomyopathy (DCM). Sixteen patients were randomized to the ICD group and 17 patients were randomized to the control group. Twenty patients (61%) were transplanted after a waiting time of 10 ± 9 months. The remaining 13 patients (39%) were not transplanted because of clinical improvement (n = 5), cerebral hemorrhage (n = 3), or death (n = 5). On the waiting list, 3 ICD patients with DCM developed slow VTs without ICD intervention, two patients with ICM (6%) had fast VT terminated by the ICD, and no arrhythmic death was observed. After 11.9 years (median), 13 of 20 HTX patients (65%) and 5 of 13 non‐HTX patients (38%) were alive. Survivors had a higher LVEF (22 ± 6 vs. 17 ± 4%, P = 0.0092) and a better exercise capacity (75 ± 29 vs. 57 ± 24 Watt, P = 0.0566) at baseline as compared to nonsurvivors. This study may not support the general use of primary preventive ICDs as a short‐term bridge to heart transplantation.

Selection for atrial fibrillation ablation: Importance of diastolic function grading.

BACKGROUND Pulmonary vein isolation (PVI) has become an accepted therapy for patients with atrial fibrillation (AF) and the indications have widened to include non-paroxysmal AF-patients. Maintenance of sinus rhythm after PVI can be adversely affected by clinical or echocardiographic parameters, which should be clearly identified. METHODS AND RESULTS After baseline clinical and echocardiographic evaluations, PVI was performed in patients with paroxysmal or non-paroxysmal AF. The follow-up strategy after PVI included: (1) clinical follow up, 12-lead electrocardiography (ECG) and 24-h ECG every 3 months, (2) trans-telephonic ECGs twice daily and when symptomatic (over 4 weeks) every 3 months, or (3) continuous monitoring via implanted devices. A recurrence was an atrial arrhythmia lasting >30s. All 340 PVI procedures of 229 patients were analyzed. On average, 1.5 PVI procedures per patient (range, 1-6 PVI) were performed. The mean age was 58±11 years (73% male) with 109 paroxysmal and 120 non-paroxysmal AF cases. Clinical follow-up with 12-lead ECGs, 24-h ECGs, trans-telephonic ECGs, and implanted devices was complete in 100%, 63%, 51%, and 16% of cases, respectively. The overall one-year recurrence rate of 59% (range, 24-82%) was dependent on grades of diastolic function (normal - dysfunction grade III) in a multivariable analysis model. Patients with normal diastolic function had the lowest recurrence rates of 24% and 49% after 1 and 3 years of follow-up, respectively (p<0.0001). CONCLUSION Diastolic function could serve as a simple summary predictor for AF recurrence, and would facilitate clinical decision-making in AF treatment.

Risk of arrhythmic death in ischemic heart disease: a prospective, controlled, observer‐blind investigation over 10 years

Risk of arrhythmic death is considered highest in ischemic heart disease with severe left ventricular ejection fraction (LVEF) reduction. Non‐invasive testing should improve decision‐making of prophylactic defibrillator (ICD) implantation.

Prolonged asystole provoked by head-up tilt testing.

SummaryWe describe a patient with a history of neurocardiogenic syncopes who had a positive headup tilt test that resulted in an lasting asystole lasting 34 seconds. However, the previously carried out Schellong test with a 30-min phase of standing showed a normal result. The patient showed typical orthostatic symptoms while tilted at the angle of 75°. Shortly before asystole occurred, heart rate variability showed high frequency bands, indicating vagal stimulation. The pathophysiology of neurocardiogenic syncope (NCS) in context with heart rate variability is discussed.This patient was successfully treated with propranolol. This case shows the utility of a provocative head-up tilt test in establishing the diagnosis of NCS. If the Schellong test is normal, still further examination by tilt-table test is indispensable.