QT Prolongation and T‐Wave Alternans during Catheter Ablation of Atrial Fibrillation: A Case Report

We report a case of a 63‐year‐old woman who developed profound QT prolongation, T‐wave alternans, and spontaneous ventricular fibrillation during catheter ablation of atrial fibrillation. A thorough search into the possible mechanisms identified the use of sevoflurane, an inhalational gas anesthetic as the culprit. The patient was converted to propofol anesthesia and her QT interval normalized promptly.     

Long‐Term Outcomes of Inducible Very Fast Ventricular Tachycardia (Cycle Length 200–250 ms) in Patients With Ischemic Cardiomyopathy

Very Fast Ventricular Tachycardia. Background: The long‐term outcomes of patients with inducible very fast ventricular tachycardia (VFVT) of cycle length (CL) 200 to 250 ms have not been well studied. Methods: Consecutive patients with ischemic cardiomyopathy with a left ventricular ejection fraction (LVEF) of ≤40% (n = 300) underwent programmed ventricular stimulation (PVS) and were divided into 4 groups based on results of the study. Group A were noninducible, had induced ventricular fibrillation (VF), or polymorphic VT (CL < 200 ms); group B had inducible VFVT (200–250 ms); group C had inducible fast ventricular tachycardia (FVT; CL 251–320 ms); and group D had inducible slow VT (CL >320 ms). The primary endpoint was spontaneous ventricular arrhythmia or sudden death. Results: The mean age was 63 ± 12 years and mean LVEF was 29 ± 7%. At mean follow‐up of 38 ± 25 months (median 30 months), the primary endpoint rate was 6.6%, 34%, 44%, and 71% in groups A, B C, and D, respectively (P < 0.001). Neither mode of induction of VT nor LVEF altered the observed pattern in the primary endpoint. There was no significant difference in the primary endpoint among implanted cardioverter defibrillator recipients in groups B and C (38% vs 45%, P = 0.43). Adjusted hazard ratios for the primary endpoint compared to group A were 3.2, 3.5, and 7.0 in groups B, C, and D, respectively (P < 0.05). Conclusions: Inducible VFVT (200–250 ms) is a clinically significant arrhythmia with adverse long‐term outcomes and should not be considered a nonspecific finding of PVS. (J Cardiovasc Electrophysiol, Vol. 21, pp. 262–269, March 2010)     

Ventricular fibrillation in a patient with Wolff‐Parkinson‐White syndrome unrelated to pre‐excited atrial fibrillation

A 52‐year‐old man was admitted due to out‐hospital cardiac arrest. Recurrent ventricular fibrillation (VF) occurred under therapeutic hypothermia thereafter. Previously inadverted full pre‐excitation was documented exclusively and immediately prior to 4 out of the 5 VF relapses. Coronary vasospasm and early repolarization were also documented. An electrophysiological study demonstrated poor anterograde conduction over a left‐sided accessory pathway. We theorize that maximum pre‐excitation favored in‐hospital VF by augmenting the repolarization vulnerability induced by therapeutic hypothermia, with coronary vasospasm accounting as the probable cause of out‐hospital VF. A plausible VF mechanism in WPW syndrome unrelated to pre‐excited atrial fibrillation is discussed.     

The prognostic significance of early and late right precordial lead (V4R) ST‐segment elevation in patients with acute anterior myocardial infarction

Background

The predictive significance of ST‐segment elevation (STE) in lead V₄R in patients with anterior ST‐segment elevation myocardial infarction (STEMI) has not been well‐understood. In this study, we evaluated the prognostic value of early and late STE in lead V₄R in patients with anterior STEMI.

Methods

A total 451 patients with anterior STEMI who treated with primary percutaneous coronary intervention (PPCI) were prospectively enrolled in this study. All patients were classified according to presence of STE (>1 mm) in lead V₄R at admission and/or 60 min after PPCI. Based on this classification, all patients were divided into three subgroups as no V₄R STE (Group 1), early but not late V₄R STE (Group 2) and late V₄R STE (Group 3).

Results

In‐hospital mortality had higher rates at group 2 and 3 and that had 2.1 and 4.1‐times higher mortality than group 1. Late V₄R STE remained as an independent risk factor for cardiogenic shock (odds ratio [OR] 2.6; 95% confidence interval [CI] 1.9–4.3; p < .001) and in‐hospital mortality (OR 2.3; 95% CI 1.8–4.1; p < .001). The 12‐month overall survival for group 1, 2, and 3 were 91.1%, 82.4%, and 71.4% respectively. However, the long‐term mortality also had the higher rate at group 3; late V₄R STE did not remain as an independent risk factor for long‐term mortality (OR 1.5; 95% CI 0.8–4.1; p: .159).

Conclusion

Late V₄R STE in patients with anterior STEMI is strongly associated with poor prognosis. The record of late V₄R in patients with anterior STEMI has an important prognostic value.

     

Long‐term follow‐up of adult patients with congenital heart disease and an implantable cardioverter defibrillator

Objective: Sudden cardiac death is common in the adult congenital heart disease (ACHD) population. Knowledge and experience about the use of implantable cardio‐ verter defibrillators (ICD) in ACHD patients is very limited. We aimed to characterize a cohort of patients with ACHD and ICDs.
Design: Thirty consecutive ACHD patients submitted to an ICD implantation in a single tertiary center were evaluated. Data on baseline clinical features, heart defect, indication for ICD, type of device, appropriate therapies, ICD‐related complication, and mortality during follow‐up were collected.
Results: Of the 30 patients, 56.7% received appropriate therapies due to ventricular tachycardia (VT) or ventricular fibrillation (VF). The rate of inappropriate therapies and device‐related complications was 33.3%. Secondary prevention and primary pre‐ vention patients with class I indications for ICD had more appropriate therapies than complication, but this relationship was reversed for patients with class II indications. Remote monitoring played an important role in diagnosing new atrial arrhythmias be‐ fore scheduled visits in 46.2% of patients, leading to a change in medication. VT/VF episodes were associated with a composite of death, cardiac transplantation, and hos‐ pital admission (OR 13.0; 95% CI: 2.1‐81.5).
Conclusion: ICDs are not only useful in preventing SCD, but also have a major role in diagnosing atrial tachyarrhythmias ahead of scheduled visits. Although improve‐ ments in ICD technology might reduce complications and inappropriate therapies, adequate selection of candidates for primary prevention still remains difficult be‐ cause of the lack of clear indications.     

Efficacy and safety of intravenous vernakalant for the rapid conversion of recent‐onset atrial fibrillation: A meta‐analysis

Background

Atrial fibrillation is a common cardiac arrhythmia with increasing prevalence in the aging population. It is a major cause of emergency department visits worldwide. Vernakalant, a relatively new antiarrhythmic drug with selectively preferential effects on the atrial tissue is currently used in many European countries for the termination of recent‐onset atrial fibrillation. Presently, the drug is still not approved by the United States Food and Drug Administration due to safety concerns. We evaluate the efficacy and safety of vernakalant for the conversion of recent‐onset atrial fibrillation or atrial flutter into normal sinus rhythm (NSR).

Methods

PubMed/MEDLINE (1993–2017), the Cochrane Central Register of Controlled Trials (2000–2017), and reference lists of relevant articles were searched for randomized controlled trials (RCTs) comparing vernakalant to a control drug and extracted subsequently.

Results

Nine RCTs were identified and included in the meta‐analysis. Pooled analysis of events extracted for a total of 1421 patients with recent‐onset atrial fibrillation showed a statistically significant increase in cardioversion within 90 minutes from drug infusion (Relative Risk [RR], 6.61; 95% Confidence Interval [CI], 2.78 – 15.71; p < .00001). In terms of adverse events, vernakalant was considered safe in comparison to control drugs (RR, 0.80; 95% CI, 0.61–1.05; p = .11).

Conclusion

Vernakalant is effective for rapid conversion of recent‐onset atrial fibrillation into NSR. However, although it showed a safe profile in terms of side effects in this analysis, we are still hesitant about this conclusion and few safety issues should be addressed within specific patients’ subgroups.

     

QT/RR Relationship in Patients after Remote Anterior Myocardial Infarction with Left Ventricular Dysfunction and Different Types of Ventricular Arrhythmias

Background: QT/RR relationship was found to be both rate‐dependent and rate‐independent, what suggests the influence of autonomic drive and other not‐autonomic related factors on it. The steeper QT/RR slope in patients after acute myocardial infarction (MI) was described, but the relationship to ventricular arrhythmias is unknown. The purpose of this study was to calculate differences in QT/RR relationship in patients after remote anterior MI with left ventricular dysfunction and different types of ventricular arrhythmias. Methods: The cohort of 95 patients (age: 63 ± 11 years, LVEF: 35 ± 9%) with previous anterior MI (mean 1.1 years) was divided into two well‐matched groups—50 patients without episodes of ventricular tachycardia (VT) or ventricular fibrillation (VF) (NoVT/VF: 39 males, 64 ± 12 years, LVEF 37 ± 8%) and 45 patients with VT and/or VF (all with ICD implanted) (VT/VF: 35 males, 62 ± 10 years, LVEF 34 ± 10%). No true antiarrhythmics were used. QT/RR slope was calculated from 24‐hour Holter ECG for the entire recording (E), daytime (D) and nighttime (N) periods. Results: Groups did not differ in basic clinical data (age, LVEF, treatment). QT/RR slopes were steeper in VT/VF than in NoVT/VF group in all analyzed periods: E ‐ 0.195 ± 0.03 versus 0.15 ± 0.03 (P < 0.001), N – 0.190 ± 0.03 versus 0.138 ± 0.03 (P < 0.001) and D ‐ 0.200 ± 0.04 versus 0.152 ± 0.03 (P < 0.001). No significant day‐to‐night differences were found in both groups. Conclusions: Steeper QT/RR slope and complete lack of day‐to‐night differences in VT/VF patients show inappropriate QT adaptation to the heart rate changes. The prognostic significance of this parameter needs prospective studies.     

Long‐Term Outcome After Catheter Ablation for Left Posterior Fascicular Ventricular Tachycardia Without Development of Left Posterior Fascicular Block

Long‐Term Outcome After Substrate‐Based Ablation of LPF VT During SR . Background: Catheter ablation of left posterior fascicular (LPF) ventricular tachycardia (VT) is commonly performed during tachycardia. This study reports on the long‐term outcome of patients undergoing ablation of LPF VT targeting the earliest retrograde activation within the posterior Purkinje fiber network during sinus rhythm (SR). Methods: This study retrospectively analyzed 24 consecutive patients (8 female; mean age 26 ± 11 years) referred for catheter ablation of electrocardiographically documented LPF VT. Programmed stimulation was performed to induce tachycardia, while mapping and ablation was aided by use of a 3D electroanatomical mapping system. Catheter ablation targeted the earliest potential suggestive of retrograde activation within the posterior Purkinje fiber network (retro‐PP) recorded along the posterior mid‐septal left ventricle during SR if LPF VT was noninducible. Results: Overall, 21/24 (87.5%) patients underwent successful catheter ablation in SR targeting the earliest retro‐PP, while 3/24 (12.5%) patients were successfully ablated during tachycardia. In none of the patients, ablation resulted in LPF block. No procedure‐related complications occurred. After a median follow‐up period of 8.9 (4.8–10.9) years, 22/24 (92%) patients were free from recurrent VT. Conclusion: In patients presenting with LPF VT, ablation of the earliest retro‐PP along the posterior mid‐septal LV during SR results in excellent long‐term outcome during a median follow‐up period of almost 9 years. (J Cardiovasc Electrophysiol, Vol. 23, pp. 1179–1184, November 2012)     

Impact of Psychotropic Drugs on QT Interval Dispersion in Adult Patients

Background

Drug-induced increase in QT dispersion has been associated with potentially fatal ventricular arrhythmias. Little is known about the use of psychotropic substances, alone or in combination with other drugs on QT dispersion.

Objectives

To evaluate the impact of psychotropic drugs on QT interval dispersion in adults.

Methods

An observational cohort study was designed involving 161 patients hospitalized from an emergency department at a tertiary hospital, divided into psychotropic users or non-users. Demographic, clinical, laboratory data and drugs used on a regular basis were collected on admission, in addition to 12-lead electrocardiogram with QT dispersion measurement.

Results

QT dispersion was significantly higher in the psychotropic user group compared to non-users (69.25 ± 25.5 ms vs. 57.08 ± 23.4 ms; p = 0.002). The QT interval corrected by Bazzett formula was also higher in the psychotropic drugs user group, with statistical significance. (439.79 ± 31.14 ms vs. 427.71 ± 28.42 ms; p = 0.011). A regression analysis model showed a positive association between the number of psychotropic drugs used and QT interval dispersion, with r = 0.341 and p < 0.001.

Conclusions

The use of psychotropic drugs was associated with increased QT dispersion and this increase was accentuated, as the number of psychotropic drugs used was higher.     

Long‐Term Results of Transcatheter Atrial Fibrillation Ablation in Patients with Impaired Left Ventricular Systolic Function

AF Ablation and Impaired Left Ventricular Function. Introduction: Long‐term outcome of AF ablation in patients with impaired LVEF is unknown. The aim of this study is to evaluate sinus rhythm (SR) maintenance, clinical status, and echocardiographic parameters over a long‐term period following atrial fibrillation (AF) transcatheter ablation in patients with left ventricular ejection fraction (LVEF) <50%. Methods and Results: A total of 196 patients (87.2% males, age 60.5 ± 10.2 years) with LVEF <50% underwent radiofrequency transcatheter ablation for paroxysmal (22.4%) or persistent (77.6%) AF. Patients were followed up for 46.2 (16.4–63.5) months regarding AF recurrences, functional class, and echocardiographic parameters. All patients underwent pulmonary vein isolation, while 167 (85.2%) required additional atrial lesions. Eleven (5.6%) patients suffered procedural complications. During follow‐up, 58 (29.6%) patients required repeated ablations. At the follow‐up end, 15 (7.7%) patients died, while 74 (37.8%) documented at least one episode of AF, atrial flutter, or atrial ectopic tachycardia. Eighty‐three (47.2%) patients maintained antiarrhythmic drugs. During follow‐up, NYHA class improved by at least one class more frequently among patients maintaining SR compared to those experiencing relapses (70.6% vs 47.9%, P = 0.003). LVEF showed a broader relative increase in patients maintaining SR (32.7% vs 21.4%; P = 0.047) and mitral regurgitation grading significantly decreased (P <0.001) only within these patients. At multivariable analysis SR maintenance emerged as an independent predictor (odds ratio 4.26, 95% CI 1.69–10.74, P = 0.002) of long‐term clinical improvement (reduction in NYHA class ≥1 and relative increase in LVEF ≥10%). Conclusions: Although not substantially worse than in patients with preserved LVEF, AF ablation in patients with impaired LVEF is affected by high long‐term recurrence rate. Among these patients SR maintenance is associated with greater clinical improvement. (J Cardiovasc Electrophysiol, Vol. 24, pp. 24‐32, January 2013)