The yield of a comprehensive investigation protocol for the diagnosis of true idiopathic ventricular fibrillation in a real-life clinical setting.

Traditionally, aborted cardiac arrest (ACA) due to documented ventricular fibrillation (VF) in the absence of structural heart disease has been termed idiopathic VF. By careful evaluation, a specific etiology can be found in a substantial proportion of patients. The aim of this survey was to assess the yield of an advanced diagnostic work-up to reveal a causative etiology in a real-life clinical setting. Patients from the University Hospital Brno's ACA database were analyzed (514 patients in total). Forty-six patients (31 males) fulfilled the inclusion criteria, which were: (1) absence of structural pathology on echocardiography; (2) absence of coronary artery disease; and (3) absence of reversible cause of ACA. The diagnostic work-up consisted in cardiac magnetic resonance imaging, stress testing, sodium channel blocker challenge, and genetic testing according to the availability of the method and patient compliance. A specific disease was found in 17 individuals (37.0%), although at least one diagnostic step was refused by 13 patients (28.3%). True idiopathic VF was confirmed in 7 patients (15.2%), for whom the entire diagnostic work-up did not reveal any specific pathology. Our real-life survey shows that, even with an incomplete diagnostic work-up (due to the unavailability of a particular method or variable patient compliance), a specific diagnosis can be identified in more than one third of the cases of "idiopathic" VF, which can thus enable targeted treatment and family screening.

Differences in right-to-left vs left-to-right interventricular conduction times in patients indicated to cardiac resynchronization therapy.

INTRODUCTION: Differences in conduction times from right ventricle to left ventricle and from left ventricle to right ventricle respectively were observed during biventricular devices implantation when changing pacing vector direction. In this article the phenomenon of interventricular conduction time differences is described and assessed in relationship to various clinical and electrophysiological parameters. METHODS: In 62 consecutive patients (9 females) interventricular conduction times between right and left ventricle in both directions were measured during cardiac resynchronization therapy device implantation procedure. Complex pacing protocol was performed. RESULTS: Investigated individuals was divided into 3 subgroups according to type of interventricular conduction pattern and statistically tested with various clinical data. Substantial differences in right-to-left vs left-to-right conduction times (> 5 ms, range 7-72 ms) were observed in 24 (39%) of all patients. They were more common in patients with dilated cardiomyopathy (20 of 38, 53%) compared to 4 (17%) of 24 patients with coronary artery disease (p = 0.011). The phenomenon occurred more often in hypertensive patients (p = 0.012). Other tested factors were nonsignificant. CONCLUSIONS: There are almost no data on this topic. The occurrence of conduction difference phenomenon is quite common in dilated cardiomyopathy while it is rare in coronary artery disease. We assume the diffuse nature of the disease and the way of remodeling of myocardium play the main role. Knowledge of this phenomenon could be useful in personalized cardiac resynchronization therapy optimization.

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. METHODS: The entire coding sequence of KCNQ1, KCNH2, SCN5A, KCNE1, and KCNE2 genes was analyzed in 45 (five females) CAD individuals-survivors of documented VF and in 90 matched healthy controls. In another control group of 141 matched patients with CAD without malignant arrhythmias, the exons containing rare coding variants found in the VF survivors were sequenced. RESULTS: The carrier frequency of all the rare sequence variants was significantly higher in the VF survivors (8/45, 17.8%) than in CAD controls (3/141, 2.2%, P = 0.001). In VF survivors, four coding variants in eight individuals were found. Three in KCNH2 gene: R148W and GAG186del are novel; P347S was previously related to long QT syndrome. In SCN5A gene, P2006A variant was found in five unrelated males. This variant has been demonstrated previously to have small effect on sodium channel kinetics. No rare coding variants were found in the healthy controls. The P2006A variant was found in three CAD controls. CONCLUSION: The prevalence of selected, rare coding variants in five long QT genes was significantly higher in cases versus controls, confirming a mechanistic role for these genes among a subgroup of patients with coronary disease and VF.

[Alternative methods of microvolt T wave alternans measurements in patients with left ventricular cardiac dysfunction]. / Alternativní metody merení mikrovolt alternans T-vlny u pacientu s dysfunkcí levé srdecní komory.

BACKGROUND: The presence of a microvolt T wave alternans (MTWA) is linked with increased risk of malignant arrhythmias and overall mortality. The most common method used for MTWA detection is a bicycle exercise test (BET). Method has still several limitations. AIM: To confirm that comparable MTWA results may be obtained by atrial and ventricular pacing during electrophysiology. To identify an anticipated relation between MTWA and malignant arrhythmia occurrence, or a death. METHODS: We obtained MTWA during BET and consequently during atrial and ventricular pacing. All patients underwent a routine electrophysiology testing prior to prophylactic ICD implantation. The results were compared. The occurrence of malignant arrhythmias and death were registered during follow-up. RESULTS: The group consisted of 39 patients. The results of MTWA obtained by BET, atrial and ventricular pacing did not show a significant difference. No difference was found among the three methods in the number of positive leads, and onset heart rate. Ventricular pacing increases the magnitude of MTWA comparing to the remaining two methods. No relation between MTWA results and occurrence of malignant arrhythmias or death was found. CONCLUSIONS: Atrial and ventricular pacing lead to comparable MTWA results as BET and may be used as alternative methods in patients where BET is not feasible.

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.

Treatment of arrhythmic storm in implantable defibrillator patients.

BACKGROUND: A common ICD therapy-related complication is arrhythmic storm (AS). The objective of our study was to define the impact of AS on patients' prognoses in order to compare the total mortality of AS patients with the rest of the group. MATERIAL/METHODS: We studied 138 patients who received ICDs between 1994 and 2001. Patients who experienced one or more arrhythmic storms were statistically compared with patients who had no accumulation of malignant arrhythmia or no episodes. RESULTS: One thousand four hundred ninety episodes of arrhythmia were analyzed. Arrhythmia recurrence was present in 71% of the patients. The majority of episodes (78%) were ventricular tachycardias and only 3% of episodes were ventricular fibrillation. Seventy percent of all arrhythmic episodes were asymptomatic. The ICD therapy sensitivity was 99.7%. Thirty-eight arrhythmic storms in 19 patients (14%) were observed during follow-up. The occurrence of AS was twice as high among patients with LVEF <35% than the rest of the group (18% vs. 8%). The total survival of patients with AS was significantly lower than that of the ICD patients who did not experience an AS (36.8% vs. 16.8%, p=0.042). All episodes of arrhythmic clusters during the AS were ventricular tachycardias. CONCLUSIONS: Arrhythmic storm is a serious risk marker for cardiac death. Ventricular tachycardia is a basic rhythm disorder of AS episodes and occurs significantly more often than ventricular fibrillation. Arrhythmic storm is responsible for a 4.6 times more frequent re-admission to hospital.

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.

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.

Endothelin-1 gene polymorphism in the identification of patients at risk for malignant ventricular arrhythmia.

BACKGROUND: The endothelins are peptides with vasoconstricting and growth-promoting properties. Endothelin-1 (ET-1) is known for its direct positive inotropic and chronotropic effects on isolated heart, and for growth effects. The aim of this pilot study was to investigate the frequency distribution of a common polymorphism of the endothelin (ET-1) gene and its possible relation to the hemodynamic consequences of malignant ventricular arrhythmia in patients with structural heart disease. MATERIAL/METHODS: We studied 26 consecutive patients with malignant ventricular arrhythmia and implantable cardioverter defibrillators (ICD), mean age 62.7 +/- 12.2 years, mean LVEF 0.37 +/- 11. The Taq polymorphism of ET-1 was detected using our original PCR method. The PCR product with a length of 358 bp in its non-mutated form contains a target sequence for the TaqI restrictive enzyme, while the mutated product loses this cleavage site. RESULTS: Out of the 26 patients, 9 (34%) had recurrent palpitations and 8 (30.8%) had syncopes during their malignant arrhythmic episodes. 19 of the patients were receiving amiodarone after ICD implantation, 7 were not. 15 patients had the (++) and 11 had the (+ -) ET-1 genotype; none had the (- -) genotype. The risk of syncopes was associated with the (++) genotype (p=0.01). Patients with amiodarone had a significantly higher frequency of the (++) genotype (p=0.011). CONCLUSIONS: All our results suggested that the presence of the (++)ET-1 genotype in patients with structural heart disease, severe left ventricular dysfunction, and malignant ventricular arrhythmia put these patients at a higher risk of hemodynamic collapse during arrhythmic episodes.