Milan Kozák

Right Ventricular Perforation with an ICD Defibrillation Lead Managed by Surgical Revision and Epicardial Leads—Case Reports

The authors present two cases of patients with perforation of the right ventricular wall by the implantable cardioverter defibrillator (ICD) lead. The complication was resolved by cardiosurgical revision and epicardial leads stitched onto the diaphragmatic wall of the heart. The perforation was identified by electrical parameter changes of the leads, echocardiography, and computed tomography. Both patients had satisfactory values of electrical parameters and ICD function with epicardial leads. The importance of regular follow‐up and a check of the lead parameters are emphasized.

Circadian variations in the occurrence of ventricular tachyarrhythmias in patients with implantable cardioverter defibrillators.

KOZÁK, M., et al.: Circadian Variations in the Occurrence of Ventricular Tachyarrhythmias in Patients with Implantable Cardioverter Defibrillators. A circadian distribution has been demonstrated in episodes of sudden cardiac death, acute myocardial infarction, ventricular premature complexes, heart rate variability, and ventricular tachyarrhythmias. The aim of this study was to evaluate the circadian distribution of ventricular tachyarrhythmia episodes in a population of ICD patients. Data were gathered from 72 patients (55 men, 17 women; mean age 62.7 ± 12.2 years, mean LVEF 0.0037 ± 0.0011 ) with ICDs implanted for standard indications. Patients were followed every 3 months over a mean period of 21 ± 12.8 months. At each examination, symptoms at arrhythmia onset and perception of ICD therapy were recorded, and the ICD memory was interrogated. During follow‐up, 1,023 episodes of malignant ventricular arrhythmias were detected and effectively terminated, 506 of which were fully analyzed. A morning peak in ventricular tachyarrhythmias was demonstrated between 7:00 and 11:00 am, and an afternoon peak between 6:00 and 7:00 pm. A significantly lower occurrence of VT was observed at 1:00 am and between 4:00 and 6:00 am. A circadian distribution in the occurrence of ventricular tachycardias was found. The three striking features of the data are: the early morning peak (about three hours after waking up), relatively stable incidence throughout waking hours, and decline in incidence in the previous period. (PACE 2003; 26:731–735)

Managed ventricular pacing compared with conventional dual-chamber pacing for elective replacement in chronically paced patients: results of the Prefer for Elective Replacement Managed Ventricular Pacing randomized study

BACKGROUND Several studies have shown that unnecessary right ventricular pacing has detrimental effects. OBJECTIVE To evaluate whether minimization of ventricular pacing as compared with standard dual-chamber pacing (DDD) improves clinical outcomes in patients referred for pacemaker or implantable cardioverter-defibrillator (ICD) replacement. METHODS In an international single-blind, multicenter, randomized controlled trial, we compared DDD with managed ventricular pacing (MVP), a pacing mode developed to minimize ventricular pacing by promoting intrinsic atrioventricular conduction. We included patients referred for device replacement with >40% ventricular pacing, no cardiac resynchronization therapy upgrade indication, no permanent atrial fibrillation (AF), and no permanent complete atrioventricular block. Follow-up was for 2 years. The primary end point was cardiovascular hospitalization. The intention-to-treat analysis was performed by using Kaplan-Meier method and the log-rank test. RESULTS We randomized 605 patients (556 referred for pacemaker and 49 referred for ICD replacement; mean age 75 ± 11 years; 365 [60%] men, at 7.7 ± 3.3 years from first device implantation) to MVP (n = 299) or DDD (n = 306). We found no significant differences in the primary end point cardiovascular hospitalization (MVP: 16.3% vs DDD: 14.5%; P = .72) and the secondary end point persistent AF (MVP: 15.4% vs DDD: 11.2%; P = .08), permanent AF (MVP: 4.1% vs DDD: 3.1%; P = .44), and composite of death and cardiovascular hospitalization (MVP: 23.9% vs DDD: 20.2%; P = .48). MVP reduced right ventricular pacing (median 5% vs 86%; Wilcoxon, P < .0001) as compared with DDD. CONCLUSIONS In patients referred for pacemaker and ICD replacement with clinically well-tolerated long-term exposure to >40% ventricular pacing in the ventricle, a strategy to minimize ventricular pacing is not superior to standard DDD in reducing incidence of cardiovascular hospitalizations.

Managed ventricular pacing vs. conventional dual-chamber pacing for elective replacements: the PreFER MVP study: clinical background, rationale, and design

AIMS Several clinical studies have shown that, in patients with intact atrioventricular (AV) conduction, unnecessary chronic right ventricular (RV) pacing can be detrimental. The managed ventricular pacing (MVP) algorithm is designed to give preference to spontaneous AV conduction, thus minimizing RV pacing. The clinical outcomes of MVP are being studied in several ongoing trials in patients undergoing a first device implantation, but it is unknown to what extent MVP is beneficial in patients with a history of ventricular pacing. The purpose of the Prefer for Elective Replacement MVP (PreFER MVP) study is to assess the superiority of the MVP algorithm to conventional pacemaker and implantable cardioverter-defibrillator programming in terms of freedom from hospitalization for cardiovascular causes in a population of patients exposed to long periods of ventricular pacing. METHODS AND RESULTS PreFER MVP is a prospective, 1:1 parallel, randomized (MVP ON/MVP OFF), single-blinded multi-centre trial. The study population consists of patients with more than 40% ventricular pacing documented with their previous device. Approximately, 600 patients will be randomized and followed for at least 24 months. The primary endpoint comprises cardiovascular hospitalization. CONCLUSION The PreFER MVP trial is the first large prospective randomized clinical trial evaluating the effect of MVP in patients with a history of RV pacing.

Association between ventricular pacing and persistent atrial fibrillation in patients indicated to elective pacemaker replacement: Results of the Prefer for Elective Replacement MVP (PreFER MVP) randomized study

BACKGROUND Pacing in the right ventricle can cause a variety of detrimental effects, including atrial tachyarrhythmias (atrial tachycardia [AT]/atrial fibrillation [AF]). OBJECTIVE The purpose of this study was to evaluate the incidence and predictors of persistent AT/AF in patients with long-term exposure to ventricular pacing. METHODS In a multicenter international trial, 605 patients (age 75 ± 11 years, 240 women) referred for replacement of an implanted pacemaker or implantable cardioverter-defibrillator (ICD), with a history of high-percentage (>40%) ventricular pacing, were randomly allocated to standard dual-chamber pacing or managed ventricular pacing (MVP), a pacing modality that minimizes ventricular pacing. The main end-point of this secondary analysis of the PreFER MVP randomized study was persistent AT/AF, defined as ≥7 consecutive days with AT/AF or AT/AF interrupted by atrial cardioversion or AT/AF present during 2 consecutive follow-up visits. RESULTS Persistent AT/AF was observed in 71 patients (11.7%) after 2 years of follow-up. At multivariable Cox regression analysis, prior AT/AF (hazard ratio [HR] 2.85, 95% confidence interval [CI] 1.20-6.22, P = .017) and ventricular pacing percentage, estimated in the first 3 months, ≥10% (HR 3.24, 95% 95% CI 1.13-9.31, P = .029) were independent predictors for persistent AT/AF. MVP was associated with persistent AT/AF risk (HR 3.41, 95% 95% CI 1.10-10.6, P = .024) in the subgroup of patients with baseline long PR interval (PR >230 ms) but not in the whole population. CONCLUSION In pacemaker and ICD replacement patients, a high percentage of ventricular pacing is associated with higher risk of persistent AT/AF. Use of algorithms that minimize right ventricular pacing may benefit patients with normal spontaneous AV conduction but should be evaluated with caution in patients with long PR interval.

Endothelin-1 gene polymorphism in patients with malignant arrhythmias.

The endothelins are peptides with vasoconstricting and growth-promoting properties. Endothelin-1 (ET-1) is known with its direct positive inotropic and chronotropic effects on isolated heart and with growth effects. The aim of this pilot study was to investigate the frequency distribution of the common polymorphism of the ET-1 gene and its possible relation with hemodynamic consequences of malignant ventricular arrhythmias in patients with structural heart disease. We studied 26 consecutive patients with malignant ventricular arrhythmias and implantable cardioverterdefibrillators with a mean age of 62.7 ± 12.2 years and a mean left ventricular ejection fraction of 0.37 ± 11.0. Taq polymorphism of ET-1 was detected using our original polymerase chain reaction method. The polymerase chain reaction product with a length of 358 basepairs (bp) (primers 5′-CAA ACC GAT GTC CTC TGT A-3′ and 5′-ACC AAA CAC ATT TCC CTA TT-3′) in its non-mutated form contains a target sequence for TaqI restrictive enzyme, while a mutated product loses this cleavage site. Of 26 patients, nine (34%) had recurrent palpitations and eight (30.8%) had syncopes during their malignant arrhythmias. Nineteen patients were given amiodarone after implantable cardioverter-defibrillator insertion and seven were not treated with amiodarone. Fifteen patients had (++), 11 (+-) and 0 (- -) ET-1 genotype. The risk for syncopes was associated with the (++) genotype of the ET-1 gene (P = 0.01). Patients receiving amiodarone had significantly higher frequency of the (++) genotype (P = 0.011). All our results indicate that the presence of the ET-1 genotype (++) in patients with structural heart disease, severe left ventricular dysfunction and malignant ventricular arrhythmias increases the risk for these patients of hemodynamic collapse during these arrhythmias.

Mutation Analysis Ion Channel Genes Ventricular Fibrillation Survivors with Coronary Artery Disease

Background: Observations from population‐based studies demonstrated a strong genetic component of sudden cardiac death. The aim of this study was to test the hypothesis that ion channel genes mutations are more common in ventricular fibrillation (VF) survivors with coronary artery disease (CAD) compared to controls.

Preliminary report: Endothelin-1 gene polymorphism in malignant ventricular arrhythmias

The aim of this study was to investigate the frequency distribution of the common polymorphism of the ET-1 gene and its possible relation to states leading to hemodynamical colaps during malignant ventricular arrhythmias (MVA) in patients with structural heart disease (SHD) and left ventricular dysfunction.