Comparison of diagnostic value using a small, single channel, P-wave centric sternal ECG monitoring patch with a standard 3-lead Holter system over 24 hours.

BACKGROUND: To compare simultaneous recordings from an external patch system specifically designed to ensure better P-wave recordings and standard Holter monitor to determine diagnostic efficacy. Holter monitors are a mainstay of clinical practice, but are cumbersome to access and wear and P-wave signal quality is frequently inadequate. METHODS: This study compared the diagnostic efficacy of the P-wave centric electrocardiogram (ECG) patch (Carnation Ambulatory Monitor) to standard 3-channel (leads V1, II, and V5) Holter monitor (Northeast Monitoring, Maynard, MA). Patients were referred to a hospital Holter clinic for standard clinical indications. Each patient wore both devices simultaneously and served as their own control. Holter and Patch reports were read in a blinded fashion by experienced electrophysiologists unaware of the findings in the other corresponding ECG recording. All patients, technicians, and physicians completed a questionnaire on comfort and ease of use, and potential complications. RESULTS: In all 50 patients, the P-wave centric patch recording system identified rhythms in 23 patients (46%) that altered management, compared to 6 Holter patients (12%), P<.001. The patch ECG intervals PR, QRS and QT correlated well with the Holter ECG intervals having correlation coefficients of 0.93, 0.86, and 0.94, respectively. Finally, 48 patients (96%) preferred wearing the patch monitor. CONCLUSIONS: A single-channel ambulatory patch ECG monitor, designed specifically to ensure that the P-wave component of the ECG be visible, resulted in a significantly improved rhythm diagnosis and avoided inaccurate diagnoses made by the standard 3-channel Holter monitor.

An entirely subcutaneous implantable cardioverter-defibrillator.

BACKGROUND: Implantable cardioverter-defibrillators (ICDs) prevent sudden death from cardiac causes in selected patients but require the use of transvenous lead systems. To eliminate the need for venous access, we designed and tested an entirely subcutaneous ICD system. METHODS: First, we conducted two short-term clinical trials to identify a suitable device configuration and assess energy requirements. We evaluated four subcutaneous ICD configurations in 78 patients who were candidates for ICD implantation and subsequently tested the best configuration in 49 additional patients to determine the subcutaneous defibrillation threshold in comparison with that of the standard transvenous ICD. Then we evaluated the long-term use of subcutaneous ICDs in a pilot study, involving 6 patients, which was followed by a trial involving 55 patients. RESULTS: The best device configuration consisted of a parasternal electrode and a left lateral thoracic pulse generator. This configuration was as effective as a transvenous ICD for terminating induced ventricular fibrillation, albeit with a significantly higher mean (+/-SD) energy requirement (36.6+/-19.8 J vs. 11.1+/-8.5 J). Among patients who received a permanent subcutaneous ICD, ventricular fibrillation was successfully detected in 100% of 137 induced episodes. Induced ventricular fibrillation was converted twice in 58 of 59 patients (98%) with the delivery of 65-J shocks in two consecutive tests. Clinically significant adverse events included two pocket infections and four lead revisions. After a mean of 10+/-1 months, the device had successfully detected and treated all 12 episodes of spontaneous, sustained ventricular tachyarrhythmia. CONCLUSIONS: In small, nonrandomized studies, an entirely subcutaneous ICD consistently detected and converted ventricular fibrillation induced during electrophysiological testing. The device also successfully detected and treated all 12 episodes of spontaneous, sustained ventricular tachyarrhythmia. (ClinicalTrials.gov numbers, NCT00399217 and NCT00853645.)

Right ventricular morphology on catheter angiography: variations and its implications for the diagnosis of arrhythmogenic right ventricular cardiomyopathy.

BACKGROUND: Catheter angiography is one modality used to diagnose right ventricular (RV) structural abnormalities in suspected arrythmogenic right ventricular dysplasia or cardiomyopathy (ARVC) patients. The appearance of the normal RV on angiography is poorly defined. This study aimed to assess RV morphology in a control group to define the range of normal appearances. METHODS: RV angiography was performed in 46 subjects (mean age 59 years; 70% male) undergoing coronary angiography for suspected coronary artery disease. Qualitative assessment for RV dilatation, regional wall motion abnormalities (RWMAs), pattern of trabeculae, and presence of micro-aneurysms was performed. Right ventricular outflow tract (RVOT) diameter was measured. RESULTS: Regional or global RV dilatation was considered to be present in 17 patients, RWMA in 13, an abnormal trabecular pattern in 10, and microaneurysms noted in two. The RVOT diameter ranged from 1.78 to 3.51 cm in right anterior oblique view and 2.33 to 4.38 cm in left anterior oblique view. CONCLUSION: The apparent prevalence of abnormal RV morphology in individuals who have no known RV pathology implies that detection of such is not necessarily of diagnostic significance in suspected ARVC. Significant inter-observer variation limits the usefulness of qualitative assessment; quantitative assessment is preferred therefore.

Symptoms and signs associated with syncope in young people with primary cardiac arrhythmias.

BACKGROUND: It is often reported that clinical symptoms are useful in differentiating cardiac from non-cardiac syncope. Studies in the young are rare. This study was designed to capture the symptoms and signs reported by patients with cardiac syncope before the patients or their attending clinicians knew the final diagnosis. METHODS: Retrospective case-note review of 35 consecutive unrelated gene-positive probands with a proven cardiac channelopathy. RESULTS: The presentation leading to diagnosis of cardiac channelopathy was resuscitated sudden cardiac death in 7 patients; syncope in 20; collapse with retained consciousness in 2; palpitations in 1 and an incidental finding in 5. For the 20 patients with syncope (LQTS 18, Brugada syndrome 2), median age at presentation was 13.9 years (1.8 day to 40.8 years). Of the 17 patients able to describe the onset of syncope, 11 (65%) had at least one symptom prior to collapse, though none reported nausea. Dizziness or lightheadedness was the most frequent symptom, being experienced by 8 (47%). Nine (of 20) patients (45%) had witnessed seizure-like activity and 8 (40%) had urinary incontinence. Nineteen patients were capable of describing the post-syncopal period, of whom 15 (79%) reported symptoms, the most common (12; 65%) being drowsiness or exhaustion. CONCLUSIONS: Cardiac syncope in the young frequently presents with symptoms and signs that are typically associated with other causes of transient loss of consciousness, including vasovagal syncope and seizure disorders. The presence of symptoms may not be as helpful in differentiating arrhythmic from non-arrhythmic events as is often supposed. A thorough history, appropriate investigations and a high index of suspicion remain essential in the assessment of syncope.

Quality of life effects of automatic external defibrillators in the home: results from the Home Automatic External Defibrillator Trial (HAT).

BACKGROUND: Public access automatic external defibrillators (AEDs) can save lives, but most deaths from out-of-hospital sudden cardiac arrest occur at home. The Home Automatic External Defibrillator Trial (HAT) found no survival advantage for adding a home AED to cardiopulmonary resuscitation (CPR) training for 7,001 patients with a prior anterior wall myocardial infarction. Quality of life (QOL) outcomes for both the patient and spouse/companion were secondary end points. METHODS: A subset of 1,007 study patients and their spouse/companions was randomly selected for ascertainment of QOL by structured interview at baseline and 12 and 24 months after enrollment. The primary QOL measures were the Medical Outcomes Study 36-Item Short-Form psychological well-being (reflecting anxiety and depression) and vitality (reflecting energy and fatigue) subscales. RESULTS: For patients and spouse/companions, the psychological well-being and vitality scales did not differ significantly between those randomly assigned an AED plus CPR training and controls who received CPR training only. None of the other QOL measures collected showed a clinically and statistically significant difference between treatment groups. Patients in the AED group were more likely to report being extremely or quite a bit reassured by their treatment assignment. Spouse/companions in the AED group reported being less often nervous about the possibility of using AED/CPR treatment than those in the CPR group. CONCLUSIONS: Adding access to a home AED to CPR training did not affect QOL either for patients with a prior anterior myocardial infarction or their spouse/companion but did provide more reassurance to the patients without increasing anxiety for spouse/companions.

Low-dose erythropoietin treatment is not associated with clinical benefits in severely anaemic Jehovah's Witnesses: a plea for a change.

BACKGROUND: Jehovah's Witnesses who refuse blood transfusion have high mortality. Erythropoietin (EPO) has been used as an alternative to blood transfusion. The optimal dosing of EPO in anaemic Jehovah's Witnesses is unknown. The aim of our study was to evaluate the clinical benefits of treatment with a low dose (<600 IU/kg/week) of epoietin beta (EPO-ß). MATERIALS AND METHODS: This was an observational study, retrospectively considering a 10-year period during which 3,529 adult Jehovah's Witnesses with a total of 10,786 hospital admissions were identified from databases of four major public hospitals in New Zealand. Patients with severe symptomatic anaemia (haemoglobin <80 g/L) who were unable to tolerate physical activity were included in the study. Patients treated without EPO were assigned to the conventional therapy group and those treated with EPO to the EPO treatment group. RESULTS: Ninety-one Jehovah's Witnesses met the eligibility criteria. Propensity score matching yielded a total of 57 patients. Patients treated with conventional therapy and those treated with EPO had similar durations of severe anaemia (average difference 6.25 days, 95% confidence interval [CI]: -3.77-16.27 days; p=0.221). The mortality rate among Jehovah's Witnesses treated with conventional therapy was 4.68 per year (95% CI: 2.23-9.82), while that in those treated with EPO was 2.77 per year (95% CI: 0.89-8.60). Treatment with EPO was associated with a mortality ratio of 0.59 (95% CI: 0.1-2.6; p=0.236). Both groups of patients had similar in-hospital survival (p=0.703). DISCUSSION: Treatment with low-dose EPO-ß was not associated with either shorter duration of severe anaemia or a reduction in mortality.

Subcutaneous chronic implantable defibrillation systems in humans.

The recent introduction of subcutaneous implantable cardioverter defibrillator (S-ICD) has raised attention about the potential of this technology for clinical use in daily clinical practice. We review the methods and results of the four studies conducted in humans for approval of this innovative technology for daily practice. Two studies using a temporary S-ICD system (acute human studies) were conducted to search for an appropriate lead configuration and energy requirements. For this purpose, 4 S-ICD configurations were tested in 78 patients at the time of transvenous (TV)-ICD implantation. The optimal configuration was tested in 49 more patients to comparatively assess the subcutaneous defibrillation threshold (S-DFT) versus the standard TV-ICD. Long-term implants were evaluated in 55 patients using an implanted system (chronic human study). The acute humans studies led to an optimal S-ICD configuration comprising a parasternal electrode and left anterolateral thoracic pulse generator. Both configurations successfully terminated 98% of induced ventricular fibrillation (VF), but significantly higher energy levels were required with S-ICD than with TV-ICD systems (36.6 ± 19.8 J vs. 11.1 ± 8.5 J). In the chronic study, all 137 VF episodes induced at time of implant were detected with a 98% conversion rate. Two pocket infections and four lead revisions were required during 10 ± 1 months of follow-up. During this period, survival was 98%, and 12 spontaneous ventricular tachyarrhythmias were detected and treated by the device. These data show that the S-ICD systems here consistently detected and converted VF induced at time of implant as well as sustained ventricular tachyarrhythmias occurring during follow-up (248).

Atrial pacing should be used more frequently in sinus node disease.

BACKGROUND: Single lead atrial (AAI(R)) pacing for sick sinus syndrome provides physiological pacing and is less expensive than a dual chamber system. Compared with ventricular-based pacing, it maintains the normal cardiac depolarization sequence, is associated with less atrial fibrillation and heart failure, and avoids pacemaker syndrome. We sought whether it is possible to select patients for AAI(R) pacing with a low likelihood of subsequent ventricular pacing, and whether this approach was cost-effective. METHODS: A retrospective review was conducted of AAI(R) pacemaker implantations. Patients requiring a further procedure for insertion of a ventricular lead (for DDD(R) or VVI(R) pacing) were compared with those who remained atrially paced. RESULTS: 2.7% (117 of 4,366) of implants were AAI(R), compared with less than 1% overall for New Zealand and Australia. During follow-up of 3.5 (2.3, 7.7) years, insertion of a ventricular lead was required in 14 (12%), and was more likely in those with pre-existing PR interval >0.20 seconds (odds ratio 7.8, P = 0.003) or left bundle branch block (LBBB, odds ratio 17, P = 0.037). Right bundle branch block, left anterior fascicular block, or history of paroxysmal atrial fibrillation were not more frequent in the group requiring ventricular pacing, and preimplantation Wenckebach point was not different. The most efficient strategy was initial AAIR implantation in all except those with LBBB or PR interval >0.20 seconds. Compared with routine DDDR implantation, cost was reduced by 20%, with a 1.4% annual incidence of further procedures. CONCLUSION: AAIR is the appropriate pacing choice for sick sinus syndrome without LBBB or PR interval >0.20 seconds.