Real world evaluation of dual-zone ICD and CRT-D programming compared to single-zone programming: the ALTITUDE REDUCES study

Tachycardia Detection, ICD, CRT‐D Devices, Appropriate and Inappropriate Shock. Introduction: We evaluated the frequency of appropriate and inappropriate shocks and survival in patients using dual‐zone programming versus single‐zone programming. Methods and Results: For the ALTITUDE REDUCES study, patients were followed for 1.6 ± 1.1 years. The 12‐month incidence of any shock was lower for dual‐versus single‐zone programmed detection at rates ≤170 bpm and between 170–200 bpm (P < 0.001). Appropriate shock rates at 1 year were also lower with dual‐zone programming in these rate intervals (single zone 9.1%, 5.4%, P < 0.001, dual zone 6.7%, 4.7%, P < 0.02). There were no detectable differences between single‐ and dual‐zone shock incidence at detection rates ≥ 200 bpm (P = 0.14). Inappropriate shock incidence was less with dual‐ versus single‐zone detection at all detect rates <200 bpm, but not at rates ≥200 bpm (P < 0.001, P = 0.37). The lowest risk of appropriate and inappropriate shock was associated with dual‐zone programming and detection rates ≥200 bpm (2.1%). Dual‐zone detection was associated with more nonsustained and diverted therapy episodes but these patients did not have an increased risk of death compared to patients with single‐zone programming. Patients programmed to low detection rate, single‐zone detection and shock‐only therapy also had the highest preshock mortality risk (P = 0.05). Conclusions: Shock incidence is lowest with either single‐ or dual‐zone detection ≥200 bpm. For detection rates <200 bpm, dual‐zone programming is associated with a reduction in the incidence of total shocks, appropriate shocks, and inappropriate shocks. (J Cardiovasc Electrophysiol, Vol. 22, pp. 1023‐1029, September 2011)     

Importance of the atrial channel for ventricular arrhythmia therapy in the dual chamber implantable cardioverter defibrillator

INTRODUCTION: Performance of dual chamber implantable cardioverter defibrillator (ICD) systems has been judged based on functioning of the ventricular tachycardia:supraventricular tachycardia (VT:SVT) discrimination criteria and DDD pacing. The purpose of this study was to evaluate the use of dual chamber diagnostics to improve the electrical and antiarrhythmic therapy of ventricular arrhythmias. METHODS AND RESULTS: Information about atrial and ventricular rhythm in relation to ventricular arrhythmia occurrence and therapy was evaluated in 724 spontaneous arrhythmia episodes detected and treated by three types of dual chamber ICDs in 41 patients with structural heart disease. Device programming was based on clinically documented and induced ventricular arrhythmias. In ambulatory patients, sinus tachycardia preceded ventricular arrhythmias more often than in the hospital during exercise testing. The incidence of these VTs could be reduced by increasing the dose of a beta-blocking agent in only two patients. In five patients in whom sinus tachycardia developed after onset of hemodynamic stable VT, propranolol was more effective than Class III antiarrhythmics combined with another beta-blocking agent with regard to the incidence of VT and pace termination. In all but three cases, atrial arrhythmias were present for a longer time before the onset of ventricular arrhythmias. During atrial arrhythmias, fast ventricular rates before the onset of ventricular rate were observed more often than RR irregularities and short-long RR sequences. Dual chamber diagnostics allowed proper interpretation of detection and therapy outcome in patients with different types of ventricular arrhythmia. CONCLUSION: The advantages of the dual chamber ICD system go further than avoiding the shortcomings of the single chamber system. Information from the atrial chamber allows better device programming and individualization of drug therapy for ventricular arrhythmia.     

Dual chamber arrhythmia detection in the implantable cardioverter defibrillator

INTRODUCTION: Dual chamber implantable cardioverter defibrillator (ICD) technology extended ICD therapy to more than termination of hemodynamically unstable ventricular tachyarrhythmias. It created the basis for dual chamber arrhythmia management in which dependable detection is important for treatment and prevention of both ventricular and atrial arrhythmias. METHODS AND RESULTS: Dual chamber detection algorithms were investigated in two Medtronic dual chamber ICDs: the 7250 Jewel AF (33 patients) and the 7271 Gem DR (31 patients). Both ICDs use the same PR Logic algorithm to interpret tachycardia as ventricular tachycardia (VT), supraventricular tachycardia (SVT), or dual (VT+ SVT). The accuracy of dual chamber detection was studied in 310 of 1,367 spontaneously occurring tachycardias in which rate criterion only was not sufficient for arrhythmia diagnosis. In 78 episodes there was a double tachycardia, in 223 episodes SVT was detected in the VT or ventricular fibrillation zone, and in 9 episodes arrhythmia was detected outside the boundaries of the PR Logic functioning. In 100% of double tachycardias the VT was correctly diagnosed and received priority treatment. SVT was seen in 59 (19%) episodes diagnosed as VT. The causes of inappropriate detection were (1) algorithm failure (inability to fulfill the PR相似文献   

Initial clinical experience with a new arrhythmia detection algorithm in dual chamber implantable cardioverter defibrillators.

AIM: Inappropriate therapy, due to poor discrimination of supraventricular tachycardia (SVT) from ventricular tachycardia (VT) remains a major problem in patients with an implantable cardioverter defibrillator (ICD). Theoretically, the addition of atrial sensing in discrimination algorithms should improve this differentiation. The aim of the study is to evaluate the performance of a new tachycardia discrimination algorithm, SMART Detection. METHODS AND RESULTS: Twenty-six patients received a non-thoracotomy ICD system (Phylax AV, Biotronik, Germany). All documented spontaneous arrhythmia episodes were analyzed. During a mean follow-up of 8 months, a total number of 139 events with stored electrograms were recorded in 12 patients. The final diagnosis was ventricular fibrillation (VF) or polymorphic VT (n=20), monomorphic VT (n=69), SVT (n=26), other ventricular arrhythmia (n=3) and T wave oversensing (n=21). In 6 episodes a dual tachycardia was present. Considering SVT episodes, inappropriate therapy occurred in 2 cases of atrial flutter due to stable ventricular rate (<30 ms), 1 case of atrial tachycardia and 2 cases of sinus tachycardia due to a sudden onset (> 10%). CONCLUSION: With the SMART Detection algorithm, discrimination of VT from SVT achieved a sensitivity of 100%, with an accuracy of 95.6% for all ventricular arrhythmias. In the case of SVT, the algorithm appropriately detected and inhibited therapy in 88% of atrial fibrillation.     

Prevalence, predictors, and mortality significance of the causative arrhythmia in patients with electrical storm

INTRODUCTION: Electrical storm (ES) is characterized by either refractory ventricular tachycardia (VT) or ventricular fibrillation (VF). However, little is known about the prevalence, predictors, and mortality implications of the causative arrhythmia in ES. We sought to assess the prevalence, predictors, and survival significance of VT and VF as the causative arrhythmia of ES in implantable cardioverter defibrillator (ICD) patients. METHODS AND RESULTS: Consecutive patients from January 2000 to December 2002 who presented to the ICD clinic with > or = 2 separate ventricular arrhythmic episodes requiring shock within 24 hours were included in the study. ICD interrogation confirmed the number of shocks and provided electrograms for interpretation of the causative arrhythmia. Patients were grouped as VF or VT according to the causative arrhythmia. Their prevalence, predictors, and mortality rates were compared. Of 2,028 patients assessed in the ICD clinic, 208 (10%) presented with ES. VF was the cause of ES in 99 of 208 patients, for an overall prevalence of 48%. Original ICD indication, coronary artery disease, and amiodarone therapy were predictive for the causative arrhythmia. There was no mortality difference between the VT and VF groups; however, both groups had significantly increased mortality compared to a control ICD population without ES. CONCLUSION: VF is the causative arrhythmia for a sizable proportion of patients with ES. The initial ICD indication, coronary artery disease, and amiodarone therapy are predictors of the causative arrhythmias in ES. There does not appear to be any mortality difference between ES patients with VT and VF, but mortality is increased in patients with ES versus control ICD patients without ES.     

Clinical experience with tiered atrial therapies and atrial arrhythmia prevention algorithms in a dual chamber cardioverter defibrillator

INTRODUCTION: The acceptance of atrial arrhythmia features in implantable cardioverter defibrillators (ICDs) will depend on their ability to appropriately discriminate atrial tachyarrhythmias/atrial fibrillation (AT/AF). This study tested the effectiveness of an atrial/ventricular ICD with advanced atrial detection and new algorithms designed to prevent atrial arrhythmias. METHODS AND RESULTS: Ninety-five patients were implanted with a dual chamber ICD (Model 1900, Guidant Corporation, MN, USA) at 25 US centers. Ten patients received a coronary sinus (CS) lead allowing a defibrillation vector for AT/AF cardioversion. Follow-up was 12.2 months. The addition of new atrial features designed for detection, discrimination, and prevention of AT/AF had no adverse effect upon detection of induced ventricular fibrillation (VF) (mean detection time with new features ON was 2.22 seconds vs 2.19 seconds with features OFF). A total of 100% of the induced and spontaneous ventricular and atrial arrhythmias receiving shock therapy were reviewed as appropriate detection. Atrial shock conversion efficacy for spontaneous and induced AT/AF episodes was 83% and 96%, respectively (144 spontaneous, 162 induced episodes). A 3-month randomized crossover trial of atrial preventative pacing features did not result in adverse effects, but there was no clinical efficacy for prevention of AT/AF. CONCLUSION: Enhanced atrial detection and discrimination features combined with tiered atrial therapies did not adversely impact the ability of the ICD (Model 1900) to appropriately detect and treat ventricular tachyarrhythmias.     

Risk of mortality for ventricular arrhythmia in ambulatory LVAD patients

Risk of Mortality for Ventricular Arrhythmia . Background: There are limited data regarding the incidence and prognostic significance of ventricular arrhythmias (VA) in ambulatory continuous flow left ventricular assist device (LVAD) patients. Methods: Sixty‐one consecutive patients from November 1, 2006 through December 31, 2010 with an LVAD and implantable cardioverter defibrillator that survived to discharge from the LVAD implantation admission were studied. Follow‐up began from date of discharge with both devices in situ and ended with death, transplant, on June 1, 2011. Pre‐LVAD VA history was related to the primary endpoints of post‐LVAD VA, mortality, and the combined endpoint of post‐LVAD VA/mortality. Results: During a mean follow‐up of 622 days 19 patients (31%) experienced VA (14 episodes of VT, 5 episodes of VF). Pre‐LVAD VA was predictive of post‐LVAD VA (hazard ratio [HR] 2.91, P = 0.026) and the combined post‐LVAD VA/mortality endpoint (HR 2.70, P = 0.021) but only displayed a nonsignificant association with mortality (HR 2.30, P = 0.11). In multivariate analysis, pre‐LVAD VA remained a significant predictor of post‐LVAD VA (HR 2.84, P = 0.03) and the combined post‐LVAD VA/mortality endpoint (HR 2.65, P = 0.025). Post‐LVAD VA was the strongest univariate predictor of mortality (HR 13.92, P < 0.001) and remained so after multivariate adjustment (HR 9.69, P = 0.001). Post‐LVAD VA occurred at a mean of 1 year from mortality events with 45% within 1 month. Conclusions: Pre‐LVAD VA is a significant predictor of post‐LVAD VA but not of mortality. VA in the continuous flow LVAD population carries a significant risk of mortality often within the first month. (J Cardiovasc Electrophysiol, Vol. 23, pp. 515‐520, May 2012)     

Long-term follow-up in patients with arrhythmogenic right ventricular cardiomyopathy

Long‐Term Prognosis in Patients with ARVC. Introduction: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a major cause of sudden cardiac death due to tachyarrhythmias. The purpose of this study was to investigate the long‐term prognosis in patients with ARVC and the incidence of rapid ventricular arrhythmias during follow‐up. Methods: Thirty ARVC patients (19 male, 63.3%, mean age 48 ± 15 years) fulfilling modified Task Force criteria 2010 were included. Of them, 13 patients (43.3%) received implantable cardioverter‐defibrillator (ICD) implantation. Rapid ventricular arrhythmia was defined as electrical storm or the occurrence of ventricular tachycardia (VT) or ventricular fibrillation (VF) with a cycle length of 240 ms or less that necessitate shock delivery to 2 or more times within a 24‐hour period. Results: With a mean follow‐up of 68 ± 10 months, 6 patients (20%) with ICD implantation had recurrent rapid VT/VF. One (3.3%) of them died of multiple shocks and SCD, and 5 (16.7%) had multiple ICD therapies due to VT/VF and electrical storm. The interval between the diagnosis of ARVC and occurrence of rapid VT/VF was 13.4 ± 4.9 months. Most (5/6, 83.3%) events of recurrent rapid VT/VF occurred within 2 years. Ablated patients who did not receive an ICD implant were totally free of rapid VT/VF. Conclusions: For patients with ARVC, long‐term prognosis is favorable. During a long‐term follow‐up, patients meeting the criteria for ICD implantation have a higher rate of rapid and potentially life‐threatening arrhythmias. However, early and clustered recurrence of rapid VT/VF in patients with an ICD is common, whereas late occurrence of rapid VT/VF is very rare. (J Cardiovasc Electrophysiol, Vol. 23, pp. 750‐756, July 2012)     

Advanced rhythm discrimination for implantable cardioverter defibrillators using electrogram vector timing and correlation

INTRODUCTION: Discrimination of ventricular and supraventricular arrhythmias remains one of the major challenges for appropriate implantable defibrillator (ICD) therapy delivery. The electrogram vector timing and correlation (VTC) algorithm was developed for such rhythm discrimination. The VTC algorithm differentiates normally conducted supraventricular beats from abnormally conducted ventricular beats by comparing the timing and correlation of rate and shock channel electrograms. METHODS AND RESULTS: Rate and shock channel electrograms of sinus rhythm and induced arrhythmias were collected from 93 patients during ICD placement. The algorithm was developed using data from 50 patients and prospectively tested in a software model with the remaining 43 patients. A sinus rhythm reference was formed by averaging complexes of the shock channel signal aligned by the peak amplitude of the rate channel. Eight features measuring the amplitude and timing of shock channel signal characteristics were extracted from the reference for comparison. When a high-rate rhythm was detected, the VTC algorithm computed the correlation of the arrhythmia complex features with the reference. Rhythms with a sufficient number of uncorrelated beats were classified as ventricular tachycardia (VT). In a dual-chamber implementation, the VTC algorithm is integrated with ventricular and atrial rate comparison (V>A) and stability above an atrial fibrillation rate threshold. The test set consisted of 117 arrhythmias. Dual-chamber sensitivity was 100% (81/81 VT) and specificity was 97% (35/36 supraventricular tachycardia). Single-chamber analysis demonstrated 99% sensitivity and 97% specificity. CONCLUSION: The VTC algorithm demonstrated high sensitivity and specificity in discriminating between ventricular and supraventricular arrhythmias.     

Differences in Outcomes Between Patients Treated with Single‐ versus Dual‐Chamber Implantable Cardioverter Defibrillators: A Substudy of the Multicenter Automatic Defibrillator Implantation Trial II

Objectives: We sought to evaluate the influence of single‐ versus dual‐chamber implantable cardioverter defibrillators (ICDs) on the occurrence of heart failure and mortality as well as appropriate and inappropriate ICD therapy in the Multicenter Automatic Defibrillator Implantation Trial II (MADIT‐II). Background: In MADIT‐II, ICD therapy in patients with a prior myocardial infarction and ejection fraction ≤0.30 was associated with a 31% reduction in risk of mortality when compared to conventionally treated patients. An unexpected finding was an increased occurrence of hospitalization for heart failure in the ICD group. Methods: Data from 717 patients randomized to ICD therapy with single‐ or dual‐chamber pacing devices in MADIT‐II were retrospectively analyzed. Endpoints selected for analysis included death from any cause, new or worsening heart failure requiring hospitalization, death or heart failure, appropriate therapy for ventricular tachycardia (VT) or ventricular fibrillation (VF), and inappropriate ICD therapy for atrial fibrillation or supraventricular tachycardia. Results: A total of 404 single‐chamber ICDs (S‐ICDs) and 313 dual‐chamber ICDs (D‐ICDs) were implanted. Patients receiving D‐ICDs were at a higher risk at baseline than those receiving S‐ICDs, with older age, higher NYHA class, more frequent prior CABG, wider QRS complex, more LBBB, higher BUN level, a history of more atrial arrhythmias requiring treatment, and a longer time interval from their index myocardial infarction to enrollment. While there was a trend toward an increase in adverse outcomes in the D‐ICD group, no statistically significant differences in heart failure or mortality were observed between S‐ICD versus D‐ICD groups. Conclusions: Patients with D‐ICDs had a nonsignificant trend toward higher mortality and heart failure rates than patients with S‐ICDs.     

ICD在恶性室性心律失常治疗中的应用

目的观察埋藏式心脏复律除颤器(ICD)在治疗恶性室性心律失常中的作用。方法对2005年1月至2009年11月在我院植入ICD的96例患者的临床资料及植入ICD后的长期随访结果进行回顾性分析,其中男80例,女16例,年龄14~79岁(53±12.2岁)。结果①植入ICD进行一级预防的患者32例(33.33%),二级预防64例(66.67%);②病因分析显示致心律失常性右室心肌病11例(11.46%),肥厚型心肌病8例(8.33%),缺血性心肌病29例(30.21%),扩张型心肌病13例(13.54%),长QT综合征1例(1.04%),Brugada综合征10例(10.42%),多形性室速19例(19.79%),特发性室颤4例(4.17%),心肌致密化不全1例(1.04%);③临床表现为持续性室速或室颤64例(66.67%),其中合并有房速16例(16.67%);④起搏模式为:单腔ICD54例(56.25%),双腔ICD42例(43.75%);⑤术中测试ICD的起搏参数并诱发心室颤动,采用20J一次电击复律成功;⑥随访结果显示植入ICD后共发生室性心律失常事件426阵次,共启动抗心动过速起搏(ATP)治疗378阵次,成功304次(成功率80.42%);高能量放电90次;有3次为窦性心动过速或房颤伴快速心室率所致的不恰当治疗。结论 ICD能有效治疗恶性室性心律失常,预防心脏性猝死;ATP是ICD治疗的有效方法;术后定期随访,及时优化ICD参数,合理选用辅助治疗,可减少不恰当治疗及提高ICD治疗的成功率。     

Ventricular Arrhythmias after LV Remodelling: Surgical Ventricular Restoration or ICD?

Ventricular arrhythmias cause ~50% of deaths in remodeled ventricles after myocardial infarction, and the Multicenter Automatic Defibrillator Implantation Trial (MADIT II) showed that the Implantable Cardioverter Defibrillator (ICD) saved lives in high risk coronary patients with advanced left ventricular dysfunction. We studied 382 patients with remodeled hearts by preoperative Ventricular stimulation (PVS) to evaluate surgical ventricular restoration (SVR) that excludes scar and lower ventricular volume alters the early and late arrhythmia process without ICD utilization.Methods: Clinical and hemodynamic results before and after SVR in post-infarction patients, are compared to contrast spontaneous and/or inducible ventricular tachycardia to patients without arrhythmias. Study arrhythmia groups included: Spontaneous in 87 patients with clinical documented ventricular arrhythmias and inducible or not inducible ventricular tachycardia: Inducible in 105 patients without clinical ventricular arrhythmias but PVS inducible ventricular tachycardia; and No arrhythmias in 190 patients without spontaneous or PVS inducible ventricular tachycardia.Results: Preoperative LV end systolic volume index helped define preoperative arrythmia potential: Spontaneous > 120/m², inducible > 100 ml/m², and none < 100ml/m². Overall operative mortality rate was 7.6% (29/382). Sudden cardiac death rate was 2.5% causing 18.7% of all deaths. Surgical management reduced inducible ventricular tachycardia, from 41% preoperatively (144/352) to 8% (26/307) at early study, and 8% (14/177) one year later. Cardiac mortality was low at 5-years and not different between groups, despite use of only one late ICD device.Conclusions: Favorable electrical success rate and low mortality always included volume reduction to interrupt functional re-entry circuits, but also added endocardiectomy, cryoablation, CABG and mitral repair when needed. Overall SVR findings show volume and shape alteration limits ventricular arrhythmias that impair prognosis, and suggests ICD devices are not needed.     

Appropriate and inappropriate electrical therapies delivered by an implantable cardioverter-defibrillator: effect on intracardiac electrogram

Intracardiac EGM After ICD Therapies. Introduction: Local injury current (LIC) seen after induced ventricular fibrillation rescue implantable cardioverter‐defibrillator (ICD) shock predicts heart failure progression. We sought to determine the frequency of LIC after spontaneous events in patients receiving ICD therapies. Methods and Results: Near‐field (NF) right ventricular (RV) EGM during 10 seconds after delivered ICD therapy was compared with baseline EGM in 420 events that occurred in 134 patients (mean age 60.8 ± 14.8, 106 [79%] male). The magnitude of elevated or depressed potential immediately after the major fast EGM deflection was defined as LIC, and its ratio to the peak‐to‐peak EGM amplitude was defined as relative LIC. LIC of at least 1 mV or relative LIC of at least 15% was considered significant. LIC was observed in 121 events (28.8%) and was detected more frequently after appropriate (43 [60.6%] events) and inappropriate (56 [64.4%] events) ICD shocks, as compared with appropriate (8 [9.2%] events) and inappropriate (3 [4.7%] events) antitachycardia pacing (ATP) or nonsustained ventricular tachycardia (11 [9.9%] events) [ANOVA P < 0.0001]. Type of ICD therapy (ICD shock vs ATP) was the most significant predictor of LIC (ATP β coefficient ?0.81; 95%CI–1.19 to 0.44); P < 0.0001), along with cycle length of tachycardia (β coefficient –0.0117; 95%CI –0.0167 to –0.0068, P < 0.00001) and shock energy (β coefficient 0.024; 95%CI 0.003–0.045, P = 0.025). Conclusion: Appropriate and inappropriate ICD shocks are frequently characterized by the development of LIC in patients with structural heart disease. Type of electrical ICD therapy, shock energy and cycle length of ventricular arrhythmia are important determinants of LIC. (J Cardiovasc Electrophysiol, Vol. 22, pp. 554‐560 May 2011)     

Effect of elapsed time from coronary revascularization to implantation of a cardioverter defibrillator on long-term survival in the MADIT-II trial

Coronary Revascularization and Long‐Term Mortality in MADIT‐II. Introduction: Coronary revascularization (CR) may reduce arrhythmia risk and improve long‐term outcome in patients with left ventricular dysfunction. This study was designed to evaluate the effect of elapsed time from CR on long‐term mortality and arrhythmic risk among patients who receive an implantable cardioverter defibrillator (ICD). Methods and Results: We evaluated the risk of 8‐year mortality by elapsed time from CR to ICD implantation (categorized as: no CR; recent CR [<2 years]; or nonrecent CR [≥2 years], and assessed as a continuous measure) among 720 ICD recipients enrolled in the Multicenter Automatic Defibrillator Trial‐II. At 8years of follow‐up, patients who did not undergo CR and those who underwent nonrecent CR had significantly higher mortality rates than patients who underwent recent CR (54%, 54%, and 36%, respectively; P < 0.001). Multivariate analysis demonstrated that no‐ and nonrecent CR were associated with respective 48% (P = 0.022) and 67% (P < 0.001) increases in mortality risk compared with recent CR. Assessment of time from CR as a continuous measure showed that every year elapsed from CR was associated with an adjusted 6% increase in 8‐year mortality (P < 0.001), and in respective 6% (P < 0.001) and 6% (P = 0.003) increased risk for in‐trial appropriate ICD therapy of ventricular tachyarrhythmias and appropriate ICD shocks. Conclusions: We observed a direct relationship between elapsed time from CR and long‐term mortality following ICD implantation. The favorable long‐term effect on outcome of recent CR may be related to a time‐dependent effect of CR on ventricular arrhythmic burden and the need for appropriate ICD shocks. (J Cardiovasc Electrophysiol, Vol. pp. 1‐6)     

Programming Antitachycardia Pacing for Primary Prevention in Patients With Implantable Cardioverter Defibrillators: Results From the PROVE Trial

Programming ATP for ICD Patients. Objectives: The PROVE trial was designed to determine if antitachycardia pacing (ATP) is clinically beneficial for primary prevention in patients who have implantable cardioverter defibrillators (ICDs) or cardiac resynchronization therapy defibrillators (CRT‐Ds). Background: Use of ICDs and CRT‐Ds reduces mortality in patients with ventricular dysfunction and mild to moderate heart failure. However, in studies of the primary prevention population, shock‐only ICDs are predominantly used, without ATP programming for less painful termination of ventricular tachycardia (VT). Methods: We conducted a prospective, nonrandomized, multicenter study using market‐released ICDs and CRT‐Ds. Patients received devices programmed to deliver ATP for VT cycle lengths of 270–330 ms. Follow‐up evaluation was performed at 3, 6, and 12 months. The incidence of VT and the rate of successful termination by ATP were analyzed. Results: Of 830 patients in the study population (men, 73%; mean age, 67.3 ± 12 years), 32% received single‐chamber ICDs, 44% dual‐chamber ICDs, and 24% CRT‐Ds. ATP was attempted for 112 VT episodes in 71 patients, and 103 (92%) of the VT episodes were successfully terminated. Three VT episodes were accelerated by ATP and required termination by ICD shock; 6 episodes terminated spontaneously or by ICD shock. Conclusions: VT is common in patients without a history of this arrhythmia who have received ICDs or CRT‐Ds for primary prevention indications. Programming ICDs for ATP therapy at the time of implantation could potentially terminate most VT episodes and reduce the number of painful shocks for these patients. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1349‐1354, December 2010)     

Analysis of implantable cardioverter defibrillator therapy in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Trial

INTRODUCTION: The implantable cardioverter defibrillator (ICD) is commonly used to treat patients with documented sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). Arrhythmia recurrence rates in these patients are high, but which patients will receive a therapy and the forms of arrhythmia recurrence (VT or VF) are poorly understood. METHODS AND RESULTS: The therapy delivered by the ICD was examined in 449 patients randomized to ICD therapy in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Trial. Events triggering ICD shocks or antitachycardia pacing (ATP) were reviewed for arrhythmia diagnosis, clinical symptoms, activity at the onset of the arrhythmia, and appropriateness and results of therapy. Both shock and ATP therapies were frequent by 2 years, with 68% of patients receiving some therapy or having an arrhythmic death. An appropriate shock was delivered in 53% of patients, and ATP was delivered in 68% of patients who had ATP activated. The first arrhythmia treated in follow-up was diagnosed as VT (63%), VF (13%), supraventricular tachycardia (18%), unknown arrhythmia (3%), or due to ICD malfunction or inappropriate sensing (3%). Acceleration of an arrhythmia by the ICD occurred in 8% of patients who received any therapy. No physical activity consistently preceded arrhythmias, nor did any single clinical factor predict the symptoms of the arrhythmia. CONCLUSION: Delivery of ICD therapy in AVID patients was common, primarily due to VT. Inappropriate ICD therapy occurred frequently. Use of ICD therapy as a surrogate endpoint for death in clinical trials should be avoided.     

The spectrum and prevalence of arrhythmia in different clinical pulmonary hypertension groups in Chinese population

BackgroundArrhythmia is not uncommon among pulmonary hypertension (PH) population, and may be associated with disease severity.HypothesisTo investigate different spectrums and prevalence of arrhythmias in different clinical PH groups in Chinese population.MethodsPatients diagnosed with PH between April 15, 2019, and August 2, 2021, were enrolled prospectively. The prevalence of different types of arrhythmias in PH patients were calculated. Logistic regression analyses were conducted to determine independent predictors for arrhythmia.ResultsOne thousand patients were enrolled. The prevalence of any arrhythmia, sinus node dysfunction, sinus tachycardia, atrial fibrillation, atrial flutter, other types of atrial tachycardia, atrioventricular block, and ventricular tachycardia is 44.4%, 12.2%, 15.2%, 8.1%, 4.1%, 10.2%, 7.1%, and 2.5%. Logistic regression analyses revealed that older age and larger right ventricle (odds ratio: 1.111 and 1.095, p < .05) were independently related with higher probability of supraventricular arrhythmia; Complicating with coronary artery disease, larger right ventricle, and increased left ventricular end‐diastolic diameter (odds ratio: 19.540, 1.106, and 1.085, p < .05) were independently correlated with sinus node dysfunction/atrioventricular block in patients with pulmonary arterial hypertension.ConclusionsNearly half of PH patients experienced at least one type of arrhythmia. The most common seen arrhythmias were supraventricular arrhythmia, sinus tachycardia, and sinus node dysfunction. Older age and larger right ventricle were independently related with higher probability of supraventricular arrhythmia; Complicating with coronary artery disease, larger right ventricle and increased left ventricular end‐diastolic diameter were independently correlated with higher probability of sinus node dysfunction/atrioventricular block in patients with pulmonary arterial hypertension.     

Long-term low-dose amiodarone therapy in the management of ventricular and supraventricular tachyarrhythmias: Efficacy and safety

Background: Amiodarone hydrochloride has been in use for two decades for the control of ventricular and supraventricular arrhythmias. Established and emerging evidence indicates that amiodarone has an antiarrhythmic efficacy superior to that of most other drugs. Hypothesis: The study was undertaken to evaluate the efficacy and acceptability of low-dose amiodarone therapy in the long-term management of supraventricular and ventricular tachyarrhythmias. Methods: A total of 124 patients with symptomatic drug-refractory or life-threatening arrhythmias managed with low-dose oral amiodarone therapy over a 10-year period was analyzed retrospectively. Of these, 45 patients (36%) had ventricular arrhythmias, 52 (42%) had atrial arrhythmias, and 27 (22%) had atrioventricular reentry tachycardia. Loading doses of amiodarone 600 mg daily for 1 week were administered for supraventricular arrhythmias and 600–1200 mg daily for 2 weeks for ventricular arrhythmias. Maintenance daily doses were 194 ± 48 and 206 ± 55 mg, respectively. Mean treatment duration was 32 ± 28 months, with 326.3 patient years of therapy. Results: Of 39 patients with sustained ventricular tachyarrhythmias, the actuarial incidence of satisfactory arrhythmia control (absence of sudden cardiac death or nonfatal arrhythmia recurrence) was 78% at 1 year and 71 % at 2 years. Satisfactory control of supraventricular arrhythmias (mean ventricular rate < 100/min with significant symptomatic improvement for sustained atrial arrhythmias and < 1 attack per year for paroxysmal atrial or atrioventricular arrhythmias) was achieved in 73, 65, and 62% of patients at 1, 2, and 3 years, respectively. The cumulative incidence of amiodarone-related adverse effects was 5.8 per 100 patient years, with drug withdrawal required in 12 patients (9.7%). Fifteen patients had thyroid dysfunction, 2 had hepatic toxicity, and 1 developed nonfatal pulmonary fibrosis. Overall, the incidence of successful use of amiodarone (satisfactory arrhythmia control and freedom from side effects) was 67, 59, and 53% at 1, 2, and 3 years, respectively. Conclusions: The results of this study suggest that the efficacy of low-dose amiodarone therapy in the management of serious ventricular and supraventricular arrhythmias would be similar to those achieved with higher doses, but with a much more acceptable side effect profile.     

Dofetilide reduces the frequency of ventricular arrhythmias and implantable cardioverter defibrillator therapies

Dofetilide Reduces VT/VF and ICD Therapies . Background: Patients with an implanted cardioverter defibrillator (ICD) and ventricular arrhythmias leading to ICD therapies have poor clinical outcomes and quality of life. Antiarrhythmic agents and catheter ablation are needed to control these arrhythmias. Dofetilide has only been approved for the treatment of atrial fibrillation. The role of dofetilide in the control of ventricular arrhythmias in patients with an ICD has not been established. Objective: Evaluate the safety and efficacy of dofetilide in a consecutive group of patients with an ICD and recurrent ventricular tachycardia (VT) and/ or ventricular fibrillation (VF) after other antiarrhythmic drugs have failed to suppress these arrhythmias. Methods: We studied 30 patients (age 59 ± 11; 5 women) with symptomatic VT or VF and ICDs for secondary prevention of sudden cardiac death. These patients had an average of 1.8 ± 4.5 episodes of VT/VF per month despite antiarrhymic therapy. Twenty‐one patients (70%) had recurrent appropriate ICD therapies prior to initiation of dofetilide, and 9 (30%) VTs below the programmed detection rate of the ICD. Twenty‐three patients (77%) had coronary artery disease. Mean ejection fraction was 30 ± 14% and 26/30 (87%) had congestive heart failure. All patients had previously failed 2 ± 1 antiarrhythmic drugs including amiodarone (n = 19) and sotalol (n = 10). Results: During the first month of treatment, 25 patients (83%) had complete suppression of VT/VF and of the 21 patients with ICD therapies 16 (76%) had no therapies during the first month of treatment. During a follow‐up period of 32 ± 32 months, dofetilide reduced the monthly episodes of VT/VF from 1.8 ± 4.5 to 1.0 ± 3.5 (P = 0.006). Monthly ICD therapies decreased from 0.9 ± 1.4 to 0.4 ± 1.7 (P = 0.037). In 9 patients that presented with slow VTs under the ICD detection zone, dofetilide reduced monthly VT/VF episodes from 0.7 ± 0.6 to 0.1 ± 0.1 (P = 0.01) and 6 (67%) had no further ICD therapies. Dofetilide was discontinued in 13 patients (43%) after 24 ± 30 months due to failure to control VT/VF (n = 7), placement of a left ventricular assist device (n = 3), catheter ablation (n = 1), heart transplantation (n = 1), and left ventricular restoration surgery (n = 1). There were 7 documented deaths (2 patients died suddenly; 3 patients of progressive heart failure; and 2 of non‐cardiac causes). Conclusions: In patients with an ICD and ventricular arrhythmias, dofetilide decreases the frequency of VT/VF and ICD therapies even when other antiarrhythmic agents, including amiodarone, have previously been ineffective. Recurrences still occur in some patients requiring catheter ablation, mechanical support, or heart transplantation. (J Cardiovasc Electrophysiol, Vol. 23 p. 296‐301, March 2012.)     

A new biomarker that predicts ventricular arrhythmia in patients with ischemic dilated cardiomyopathy: Galectin-3

IntroductionVentricular arrhythmias are caused by scar tissue in patients with ischemic dilated cardiomyopathy. The gold standard imaging technique for detecting scar tissue is magnetic resonance imaging (MRI). However, MRI is not feasible for use as a screening test, and also cannot be used in patients who have received an implantable cardioverter-defibrillator (ICD). In this study, we aimed to assess the association between levels of galectin-3 (Gal-3), which is known to be secreted by scar tissue, and the history of ventricular arrhythmias in patients with ischemic dilated cardiomyopathy who received an ICD.MethodsNineteen healthy controls and 32 patients who had previously undergone VVI-ICD implantation due to ischemic dilated cardiomyopathy were enrolled in the study. Patients were divided into three groups: the first group including patients who had received no ICD therapies, the second including patients with arrhythmia requiring therapies with no arrhythmia storm, and the third including patients who had arrhythmia storm. We assessed the association between Gal-3 levels and the history of ventricular arrhythmias in these patients.ResultsGal-3 levels were significantly higher in the patient groups than in the control group (p<0.01). Gal-3 levels of patients with arrhythmias requiring ICD therapies were significantly higher than in patients with ICD not requiring therapies (p=0.02). They were also higher in patients with a history of arrhythmia storm than in patients without shocks (p=0.05). Receiver operating curve analysis showed with 84% sensitivity and 75% specificity that Gal-3 levels over 7 ng/ml indicated ventricular arrhythmia that required therapies.ConclusionGal-3 may be used to further improve risk stratification in patients with ischemic cardiomyopathy who are more prone to developing life-threatening arrhythmias.