Is flecainide dangerous in long QT-3 patients?

Mutations of the cardiac sodium channel gene, SCN5A, are present in both long-QT and Brugada syndromes. Flecainide is used as a provocative test to unmask the electrocardiogram (ECG) phenotype of the Brugada syndrome, as well as long-term treatment for long QT-3 syndrome, since it shortens the QT interval. We report a case where oral flecainide induced syncope with a Brugada ECG pattern in a patient with known long QT-3 syndrome.

The effect of patient sex on recurrence of atrial fibrillation following successful direct current cardioversion.

BACKGROUND: The effect of patient sex on recurrence of atrial fibrillation after a successful direct current cardioversion is unknown. METHODS: This prospective study included 773 patients (486 [63%] men and 287 [37%] women) undergoing successful direct current cardioversion of atrial fibrillation between May 2000 and July 2003. Patient characteristics at presentation were recorded. The primary end point was the time between cardioversion and the first documented recurrence of arrhythmia. RESULTS: At presentation, women were older and had a higher prevalence of hypertension and valvular disease compared with men. In addition, women had worse mechanical left atrial appendage function. Arrhythmia recurrence was more prevalent in women (50.0% at 1 year compared with 43.4% in men, and 75.8% at 2 years compared with 67.0% in men; P = .03). On the basis of multivariate analysis, patient sex was a significant predictor of arrhythmia recurrence. There was no significant difference in overall mortality between men and women. CONCLUSIONS: Women were more likely than men to have recurrence of atrial fibrillation after successful direct current cardioversion. Patient sex should be taken into account with other clinical factors when making the decision about cardioversion for atrial fibrillation.

Comparative efficacy of monophasic and biphasic waveforms for transthoracic cardioversion of atrial fibrillation and atrial flutter.

BACKGROUND: Transthoracic cardioversion fails to restore sinus rhythm in 6% to 33% of patients with atrial fibrillation. This study sought to determine the relative efficacy of biphasic waveforms compared with monophasic waveforms in the treatment of atrial arrhythmias. METHODS: A total of 912 patients underwent 1022 transthoracic cardioversions between May 2000 and December 2001. A monophasic damped sine waveform was used in the first 304 cases, and a rectilinear biphasic defibrillator was used in the next 718 cases. RESULTS: Use of a biphasic waveform was associated with 94% success in conversion to sinus rhythm compared with 84% with a monophasic waveform (P < .001). The cumulative energy required to restore sinus rhythm was lower with biphasic shocks in both atrial fibrillation and atrial flutter groups (554 +/- 413 J for monophasic vs 199 +/- 216 J for biphasic shocks in the atrial fibrillation group, P < .001; 251 +/- 302 J vs 108 +/- 184 J, respectively, in the atrial flutter group, P < .001). In a multivariate analysis, use of a biphasic shock was associated with a 3.9-fold increase in success of cardioversion. CONCLUSION: When used to cardiovert atrial arrhythmias, the rectilinear biphasic waveform was associated with higher success rates and lower cumulative energies than the monophasic damped sine waveform.

Upper limit of vulnerability determination during implantable cardioverter-defibrillator placement to minimize ventricular fibrillation inductions.

The defibrillation threshold (DFT) and upper limit of vulnerability (ULV) were determined using step-down protocols in 50 patients who underwent implantable cardioverter-defibrillator placement or testing. The sensitivity and specificity of each ULV energy level was assessed for detecting an increased DFT, correlation of the DFT and ULV, and optimal shock timing for ULV determination. A ULV <10 or 11 J (failure to induce ventricular fibrillation with 10- to 11-J shocks) was 100% predictive of an acceptable DFT and may be sufficient to exclude unacceptable DFTs in 60% of implantable cardioverter-defibrillator recipients. All 4 shocks used to scan the peak of the T wave during ULV testing were necessary for accurate ULV determination.

Randomized comparison of J-shaped atrial leads with and without active fixation mechanism.

BACKGROUND: In this prospective, randomized, controlled study, we compared the performance of J-shaped active fixation (AF) atrial leads with J-shaped passive fixation (PF) leads, over a 1-year follow-up period. METHODS: A total of 200 consecutive patients were prospectively randomized for implantation with a Medtronic 5568 AF lead model (n = 103; Minneapolis, MN, USA) versus a Medtronic 5592 PF model (n = 97), and all lead-related measurements and complications were recorded over one year. RESULTS: All leads were successfully implanted with a nonsignificant difference in crossover rate to the alternative lead due to failed implantation (1 in the AF and 4 in the PF group, P = NS). Fluoroscopy time during implantation procedure was significantly shorter in the PF group (2.1 +/- 3.6 vs 3.3 +/- 4.5 minute, P < 0.05). Pacing thresholds during implantation were significantly lower in patients with PF leads (0.7 +/- 0.3 V vs 0.9 +/- 0.3 V, P < 0.001) and this difference persisted at 1-year follow-up (0.8 +/- 0.6 V vs 1.3 +/- 0.9 V in PF and AF leads respectively, P < 0.05). Lead-related complications occurred in PF and AF with similar frequency (4% and 9% respectively, P = 0.2). However, pericardial complications occurred only in the AF group (6 cases, P = 0.01). Lead dislodgement was observed in only two cases-both in the PF group (P = 0.3). CONCLUSION: Both types of J-shaped atrial leads had reasonable performance. PF leads required shorter fluoroscopy time for implantation, demonstrated a better pacing threshold over a 1-year follow-up period and had no pericardial complications, while AF lead implantation was complicated by pericardial irritation and/or effusion in 6% cases (P = 0.01).

Clinical surveillance of a tined, bipolar, silicone-insulated ventricular pacing lead.

AIMS: This study assesses short- and long-term performance of the S80TB ventricular lead manufactured by Sorin Biomedica, Italy. METHODS AND RESULTS: Three hundred and thirty leads were implanted and had complete follow-up with us for a minimum of 60 months or up to failure, removal, and/or patient death (mean 40 months, range: 1 day to 81 months). Thirty-two patients (9.6%) had spontaneous lead-related complications: 7 (2.1%) occurred during the first week; 25 (7.6%) had chronic complications, of which 20 (6.1%) necessitated re-operations; 3 (0.9%) were lead material failures. Of the 110 re-operations (90 pacemaker replacements and 20 operations due to complications), 7 additional cases (6.4%) were complicated by unique connector damage that occurred during disconnection of the lead from the connector block. The Kaplan-Meier estimated 5-year lead survival free of lead material failure and free of any significant lead complication were 97.9 and 87%, respectively. CONCLUSION: The S80TB lead demonstrates an acceptable rate of acute and chronic spontaneous complications and very few lead material failures over 5 years of follow-up. However, there seems to be a relatively high incidence of connector damage during disconnection from the connector block. Extra caution is required during those procedures in patients with this lead.

Optimal combination of discriminators for differentiating ventricular from supraventricular tachycardia by dual-chamber defibrillators.

UNLABELLED: Discriminators for ventricular/supraventricular tachycardia. INTRODUCTION: Dual-chamber implantable cardioverter defibrillators (ICDs) use discriminators to differentiate between supraventricular tachycardias (SVTs) and ventricular tachycardias (VT), the accuracy of which may depend on the type and method used. ICDs can combine rate branching of tachyarrhythmias according to their A:V relationship with two SVT-VT discriminators in each rate branch, using ANY (either) or ALL (both) logic. Our goal was to determine the optimal discriminator combination. METHODS: Stored electrogram data from 596 spontaneous tachyarrhythmias from 203 patients with Photon DR ICDs were analyzed. Arrhythmias are first classified by the relationship of atrial and ventricular rates (rate branches VA) followed by additional discriminators: morphology and/or sudden onset if V=A; morphology and/or interval stability if VV branch: ANY logic provided adequate sensitivity. The combination of morphology only in V=A with interval stability or morphology (ANY logic) in V

Use of advanced mapping systems to guide ablation in complex cases: experience with noncontact mapping and electroanatomic mapping systems.

OBJECTIVE: This report describes our experience with noncontact mapping and electroanatomic mapping in complex ablations, which are defined as ablations done after failure of conventional ablation. MATERIAL AND METHODS: Patients were included (N = 68; 49% with structural heart disease) in whom previous ablation failed and in whom a second procedure was done with advanced mapping. Non-contact mapping was used in 17 patients, electroanatomic mapping in 36, and both noncontact and electroanatomic mapping in 15. Arrhythmias included focal atrial tachycardia (n = 16), reentrant atrial tachycardia (n = 14), right ventricular outflow tachycardia (n = 10), post-myocardial infarction ventricular tachycardia (n = 9), and others (n = 19). RESULTS: Acute success at the second ablation was achieved in 79% of patients. At 20 +/- 9 months after the procedure, 69% of these patients reported having significantly fewer symptoms than before the second ablation, and 51% were free of symptoms. Only 16% were using antiarrhythmic medications. Complications included a small pericardial effusion in two patients, hypotension in one patient, and a femoral pseudoaneurysm in another. CONCLUSIONS: Advanced mapping is a useful and safe adjunct for catheter ablation after ablation has failed in patients with complex substrate.

Discrepancies between the upper limit of vulnerability and defibrillation threshold: prevalence and clinical predictors.

INTRODUCTION: Upper limit of vulnerability (ULV) has a strong correlation with defibrillation threshold (DFT) in patients with implantable cardioverter defibrillators (ICDs). Significant discrepancies between ULV and DFT are infrequent. The aim of this study was to characterize patients with such discrepancies. METHODS AND RESULTS: The ULV and DFT were determined in 167 ICD patients. Univariate and multivariate analyses were used to evaluate clinical predictors of a significant difference (> or =10 J) between ULV and DFT. Only 8 patients (5%) had > or =10 J difference. ULV exceeded DFT in all of them. Absence of coronary artery disease (6/8 vs 48/159 patients; P = 0.05) and absence of documented ventricular arrhythmias (4/8 vs 12/159 patients; P = 0.01) were the only independent predictors of a significant ULV-DFT discrepancy. CONCLUSION: Significant discrepancies between ULV and DFT occur in 5% of patients with ICDs. Absence of coronary disease and documented ventricular arrhythmias predict such a discrepancy. At ICD implant, DFT testing is recommended in these patients and in patients with a high (>20 J) ULV before first-shock energy and the need for lead repositioning are determined.

Long-term outcome of patients who received implantable cardioverter defibrillators for stable ventricular tachycardia.

INTRODUCTION: Evidence is inconclusive concerning the role of implantable cardioverter defibrillators (ICDs) to treat patients with hemodynamically stable ventricular tachycardia (VT). The goal of this study was to estimate future risk of unstable ventricular arrhythmias in patients who received ICDs for stable VT. METHODS AND RESULTS: We reviewed complete ICD follow-up data from 82 patients (age 66.1 +/- 11.3 years; left ventricular ejection fraction 32.3%+/- 11.2%; mean +/- SD) who received ICDs for stable VT. During the follow-up period of 23.6 +/- 21.5 months (mean +/- SD), 15 patients (18%) died, and 10 (12%) developed unstable ventricular arrhythmia, 8 of whom had the unstable arrhythmia as the first arrhythmia after ICD placement. Estimated 2- and 4-year survival in the whole group was 80% and 74%, respectively. Estimated 2- and 4-year probability of any VT and unstable VT was 67% and 77% and 11% and 25%, respectively. There were no differences in age, ejection fraction, sex, underlying heart disease, cycle length, symptoms, baseline electrophysiologic study results, or QRS characteristics of qualifying VT between patients who developed unstable ventricular arrhythmia and patients who did not. Twenty-nine patients (35%) had at least one inappropriate shock, and 11 (13%) underwent further surgery for ICD-related complications. CONCLUSION: Patients who present with hemodynamically stable VT are at risk for subsequent unstable VT. ICD treatment offers potential salvage of patients with stable VT who subsequently develop unstable VT/ventricular fibrillation, although complications and inappropriate shocks are considerable. No predictors could be found for high and low risk for unstable arrhythmias. These findings support ICD treatment for stable VT survivors.