Influence of the vectorcardiogram synthesis matrix on the power of the electrocardiogram-derived spatial QRS-T angle to predict arrhythmias in patients with ischemic heart disease and systolic left ventricular dysfunction

Background and Purpose

Several studies have demonstrated that the spatial mean QRS-T angle (SA) predicts cardiac events and mortality. Spatial mean QRS-T angle is a vectorcardiographic variable. Because in clinical practice, 12-lead standard electrocardiograms (ECGs) are recorded rather than vectorcardiograms (VCGs) according to Frank, VCGs are commonly obtained by synthesizing them from 12-lead ECGs, by using a VCG synthesis matrix. Hence, the thus computed SA is an estimate of the real SA measured in the Frank VCG. Recent studies have shown that Kors VCG synthesis matrix yields better estimates of SA than the inverse Dower VCG synthesis matrix. Our current study aims to compare the predictive power of these SA variants for the occurrence of potentially lethal arrhythmias.

Methods

The study group consisted of patients with ischemic heart disease and left ventricular systolic dysfunction who received an implantable cardioverter-defibrillator (ICD) for primary prevention. During follow-up, the occurrence of appropriate device therapy (occurrence of ventricular arrhythmia) was noted. Alternative SAs were computed in VCGs synthesized from standard 12-lead ECGs by using either the inverse Dower matrix (SA-Dower) or the Kors matrix (SA-Kors). Comparison of the predictive power of SA-Dower and SA- Kors was performed by receiver operating characteristic analysis, by Kaplan-Meier analysis, and by univariate and multivariate Cox regression analysis, using every 10th percentile of SA as a cutoff value.

Results

The study group consisted of 412 patients (361 men; mean ± SD age 63 ± 11 years), in which 56 patients had appropriate ICD therapy during follow-up. Receiver operating characteristic analysis revealed that the area under the curve of SA-Kors was significantly larger than area under the curve of SA-Dower (0.646 vs 0.607, P = .043). The discriminative power of SA-Kors for the absence/presence of appropriate ICD therapy in patients during follow-up was generally superior to SA-Dower over a wide range of cutoff values in the Kaplan-Meier analysis and generally yielded stronger hazard ratios in the univariate and multivariate Cox regression analyses.

Conclusion

If there is no specific reason to use the inverse Dower matrix, VCG synthesis from standard 12-lead ECGs should preferably be done by using the Kors matrix. It is likely to assume that already published studies in which the predictive value of SA-Dower was demonstrated would yield stronger results if the SA-Dower angles were substituted by SA-Kors angles.     

Implantation-related complications of implantable cardioverter-defibrillators and cardiac resynchronization therapy devices: a systematic review of randomized clinical trials

The number of implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy (CRT) implantations is increasing drastically worldwide, and hence, the number of implanting centers is also increasing. Despite abundant data on the beneficial effect of these devices, little is known regarding safety and complication rates. Eleven ICD and 7 CRT trials were systematically reviewed to provide data on the frequency of in-hospital mortality and complications related to the implantation. Average in-hospital mortality was 2.7% in trials using both thoracotomy and nonthoracotomy ICDs, 0.2% in trials using nonthoracotomy ICDs, and 0.3% in CRT trials. The pneumothorax rate was similar between the nonthoracotomy ICD and CRT trials (0.9%) Coronary sinus complications occurred in 2.0% of patients undergoing CRT. Lead dislodgement rates were higher in CRT trials (5.7%) than in nonthoracotomy ICD trials (1.8%).     

Regional lymph node irradiation in breast cancer

A recent meta-analysis, published by the Early Breast Cancer Trialists' Collaborative Group, demonstrated a clear survival advantage of post-operative radiotherapy on the breast, chest wall and regional lymphatics in node-positive disease. The extensive target volume in locoregional irradiation of breast cancer, in close proximity to the heart and lungs, complicates treatment planning. The breast or chest wall fields need to match the supraclavicular/axillary and parasternal fields, at the subclavicular and parasternal matchline, respectively. Dose distribution near the junction area is often inhomogeneous, and under- and over-dosage can occur, which can lead to recurrences and complications. This paper describes briefly the indications, complications and target localization concerning regional lymph node radiotherapy and discusses more extensively the advantages and disadvantages of the most frequently used treatment techniques.     

Update on small-diameter implantable cardioverter-defibrillator leads performance

Background: The performance of small diameter implantable cardioverter defibrillator (ICD) leads is questionable. However, data on performance during long‐term follow‐up are scarce. The aim of this study is to provide an update for the lead failure and cardiac perforation rate of Medtronic's Sprint Fidelis ICD lead (Medtronic Inc., Minneapolis, MN, USA) and St. Jude Medical's Riata ICD lead (St. Jude Medical Inc., St. Paul, MN, USA). Methods: Since 1996, all ICD system implantations at the Leiden University Medical Center, the Netherlands, are registered. For this study, data up to February 2011 on 396 Sprint Fidelis leads (follow‐up 3.4 ± 1.5 years), 165 8‐French (F) Riata leads (follow‐up 4.6 ± 2.6 years), and 30 7‐F Riata leads (follow‐up 2.9 ± 1.3 years) were compared with a benchmark cohort of 1,602 ICD leads (follow‐up 3.4 ± 2.7 years) and assessed for the occurrence of lead failure and cardiac perforation. Results: During follow‐up, the yearly lead failure rate of the Sprint Fidelis lead, 7‐F Riata lead, 8‐F Riata lead, and the benchmark cohort was 3.54%, 2.28%, 0.78%, and 1.14%, respectively. In comparison to the benchmark cohort, the adjusted hazard ratio of lead failure was 3.7 (95% confidence interval [CI] 2.4–5.7, P < 0.001) for the Sprint Fidelis lead and 4.2 (95% CI 1.0–18.0, P < 0.05) for the 7‐F Riata lead. One cardiac perforation was observed (3.3%) in the 7‐F Riata group versus none in the 8‐F Riata and Sprint Fidelis lead population. Conclusion: The current update demonstrates that the risk of lead failure during long‐term follow‐up is significantly increased for both the Sprint Fidelis and the 7‐F Riata lead in comparison to the benchmark cohort. Only one cardiac perforation occurred. (PACE 2012; 35:652–658)     

The effect of magnesium oral therapy on spasticity in a patient with multiple sclerosis

The effects of magnesium glycerophosphate oral therapy on spasticity was studied in a 35-year-old woman with severe spastic paraplegia resulting from multiple sclerosis (MS). We found a significant improvement in the spasticity after only 1 week from the onset of the treatment on the modified Ashworth scale, an improvement in the range of motion and in the measures of angles at resting position in lower limbs. No side-effects were reported and there was no weakness in the arms during the treatment.     

The rationale and design of the Shockless IMPLant Evaluation (SIMPLE) trial: A randomized, controlled trial of defibrillation testing at the time of defibrillator implantation

Defibrillation testing (DT) has been an integral part of defibrillator (implantable cardioverter defibrillator [ICD]) implantation; however, there is little evidence that it improves outcomes. Surveys show a trend toward ICD implantation without DT, which now exceeds 30% to 60% in some regions. Because there is no evidence to support dramatic shift in practice, a randomized trial is urgently needed. The SIMPLE trial will determine if ICD implantation without any DT is noninferior to implantation with DT. Patients will be eligible if they are receiving their first ICD using a Boston Scientific device (Boston Scientific, Natick, MA). Patients will be randomized to DT or no DT at the time of ICD implantation. In the DT arm, physicians will make all reasonable efforts to ensure 1 successful intraoperative defibrillation at 17 J or 2 at 21 J. The first clinical shock in all tachycardia zones will be set to 31 J for all patients. The primary outcome of SIMPLE will be the composite of ineffective appropriate shock or arrhythmic death. The safety outcome of SIMPLE will include a composite of potentially DT-related procedural complications within 30 days of ICD implantation. Several secondary outcomes will be evaluated, including all-cause mortality and heart failure hospitalization. Enrollment of 2,500 patients with 3.5-year mean follow-up will provide sufficient statistical power to demonstrate noninferiority. The study is being performed at approximately 90 centers in Canada, Europe, Israel, and Asia Pacific with final results expected in 2013.     

Effect of cardiac resynchronization therapy on inducibility of ventricular tachyarrhythmias in cardiac arrest survivors with either ischemic or idiopathic dilated cardiomyopathy

We evaluated whether long-term cardiac resynchronization therapy affects the inducibility of ventricular tachyarrhythmias in relation to reverse remodeling in cardiac arrest survivors with either ischemic or idiopathic dilated cardiomyopathy. Clinical, electrophysiologic, and echocardiographic data of 18 patients were obtained before and after 6 months of cardiac resynchronization.     

Eligibility for biventricular pacing in patients with an implantable cardioverter defibrillator

Implantable cardioverter defibrillator (ICD)-therapy prevents sudden death in patients at high risk, but incidence of death due to heart failure remains unaltered. Recent data suggest that biventricular (BV) pacing is useful in patients with heart failure. It is unclear, how many patients with an ICD indication may have an indication for BV pacing. Therefore all patients who received an ICD were analyzed for eligibility of BV pacing using the following criteria: NYHA class III or IV, QRS duration >120 ms, depressed LVEF. Three hundred and ninety consecutive patients received an ICD from June 1996 to March 2001. Underlying disease was ischemic heart disease in 66%. In the 390 patients the mean LVEF was 36+/-17%, 20% were in NYHA class III-IV and 16% were in NYHA class II with an LVEF <30%. Of these 140 patients, 79 had a QRS duration >120 ms. Thus, 79 (20%) patients were eligible for BV pacing in addition to ICD-therapy. Patients who received a BV pacemaker in addition to ICD-therapy had a superior survival, improved in NYHA class and showed a significantly lower hospitalization rate as compared to patients who received an ICD only. Screening for eligibility of BV pacing may be considered in patients with CHF scheduled for ICD implantation.