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)     

Prevention of Recurrent Life-threatening Ventricular Arrhythmias by Temporary Cardiac Pacing

ABSTRACT Overdrive pacing has been applied in 26 patients to prevent frequent recurrent ventricular fibrillation (VF) and ventricular tachycardia (VT) occurring in the setting of ventricular extrasystole of 2–5 degrees graded by Lown. These patients had 3–47 recurrent attacks of VF and VT (11.4±2.4) which were not prevented with antiarrhythmic agents. Overdrive pacing was continued for 2–236 hours (21.3±3.7) and appeared to be effective in 23 (88.4%) of the 26 patients including those with prolonged QT intervals. Atrial pacing was more effective than ventricular overdriving and required stimulation at a slower rate. Antiarrhythmic therapy and overdrive pacing in combination were more effective than both used independently. Suppression of ventricular extrasystole and prevention of life-threatening arrhythmias were achieved by increasing the heart rate by 23.2±4.5 beats/min.     

Biventricular pacing reduces ventricular arrhythmic burden and defibrillator therapies in patients with heart failure

BACKGROUND: Cardiac resynchronization therapy (CRT) has recently emerged as a new modality for the treatment of patients with advanced heart failure (HF). HYPOTHESIS: Cardiac resynchronization therapy reduces atrial and ventricular arrhythmia burdens. METHODS: We analyzed the clinical data of patients who underwent an upgrade from a dual-chamber to a biventricular implantable cardioverter-defibrillator (ICD) at a tertiary care center. RESULTS: Nineteen patients (age 67 +/- 10 years, 18 men, left ventricular [LV] ejection fraction 0.24 +/- 0.07) underwent an upgrade to CRT-ICD. The LV lead was placed in a lateral position in 11, posterolateral in 4, and anterolateral in 3 patients. Baseline New York Heart Association class of HF improved in 11 (58%) patients who were considered "responders." After adjusting for the duration of follow-up before and after the upgrade, the number of patients receiving any ICD therapy decreased significantly from 13 to 4 (p = 0.004) and the total number of therapies decreased from 72 to 17 (p = 0.067). Also, the number of detections of sustained ventricular arrhythmias decreased from 40 to 11 episodes (p = 0.05), but the decrease in the number of detected supraventricular arrhythmias and mode switch episodes was not significant. The reduction in the ventricular arrhythmia load was independent of whether or not the patient responded to CRT. CONCLUSION: Our data suggest that CRT reduces ventricular but not atrial arrhythmia burden in patients with HF irrespective of their clinical response. This suggests that the reduction in arrhythmia is primarily an electrical phenomenon. Further studies are needed to confirm these findings and to uncover their underlying mechanisms.     

A Hemodynamically Responsive Antitachycardia System: Theoretical Bases for Design

Current antitachycardia systems such as the automatic implantable cardioverter/defibrillator (AICD), detect tachyarrhythmias primarily by sensing rate and thereby perform inadequately in differentiating hemodynamically stable from unstable arrhythmias. As a result, these devices may discharge during stable tachycardias (such as sinus tachycardia), causing discomfort to the patient and depleting the device's limited energy supply. If a parameter which could reflect the particular hemodynamic state of a tachycardia were incorporated into the sensing algorithm of these systems, function may be more hemodynamically precise and discharge specificity may be improved.     

Atrial Pacing Therapies for Prevention of Atrial Fibrillation in Patients with Implantable Defibrillators

Atrial fibrillation (AF), atrial flutter and atrial tachycardia (AT) occur frequently in patients following implantation of an implantable cardioverter defibrillator (ICD) for the treatment of ventricular tachyarrhythmias. Some new generation ICDs have incorporated atrial antitachycardia pacing therapy (ATP) and atrial pacing algorithms designed specifically for the prevention of AF. In the GEM III AT clinical evaluation, atrial ATP efficacy for termination of AF and AT was assessed. Overall ATP efficacy for AF/AT, based on device classification, was 40% when adjusted using the Generalized Estimating Equations to account for correlated data that arises from utilizing multiple episodes in some patients. However, many episodes of AF/AT were noted to terminate within 10 minutes of onset. Applying a more conservative definition of efficacy, termination within 20 sec of delivery of the last atrial ATP, efficacy for termination of AF/AT was 26%. 50 Hz burst pacing was shown to have minimal efficacy for termination of AF and modest incremental benefit following ramp or burst pacing therapies for AT. These observations provide a more realistic expectation of the value of atrial ATP in the ICD population with AF. Atrial ATP terminates some episodes of AT but previously reported efficacy rates of 40-50% are exaggerated and in part reflect spontaneous terminations of some AF/AT episodes.     

Entrainment of Ventricular Tachycardia with a Permanent Biventricular Pacemaker

Biventricular pacing has been introduced as a treatment for congestive heart failure. These devices presently pace and sense from two disparate ventricular sites. Antitachycardia pacing (ATP) is used for termination of sustained monomorphic ventricular tachycardia (VT) and has been incorporated with simultaneous dual site ventricular pacing for treatment of VT. We report a case of entrainment of sustained monomorphic VT in a 62-year-old female with an ischemic cardiomyopathy and VT, who received a biventricular pacemaker-implantable cardioverter defibrillator, Contak CD (Guidant, St. Paul, MN). Biventricular pacing sites were at the right ventricular apex and the middle of the anterior cardiac vein on the left ventricle. The entrained VT has a left bundle branch block and left axis deviation morphology with a cycle length of 350 msec. ATP at 270 msec produced concealed entrainment of an induced VT. Only one pacing site demonstrated capture. The inability to capture both pacing sites simultaneously was the result of ventricular refractoriness at one of the sites during ATP of the VT. The entrance and exit points of the loop for VT appeared to rest between the two pacing sites in the intraventricular septum. This case illustrates one of the sensing limitations of today's biventricular pacing defibrillator systems.     

Efficacy of intrinsic antitachycardia pacing for ventricular tachycardia refractory to conventional burst pacing: A case series

Intrinsic antitachycardia pacing (iATP) is a novel automated ventricular ATP algorithm that designs ATP sequences based on the analysis of prior failed ATP. Real-world data on the efficacy and safety of iATP are lacking. Among 124 ventricular tachycardia (VT) episodes in 130 consecutive patients (mean age at implantation: 63.8 ± 14.9 years; sex, 95 male and 35 female) for whom implantable cardioverter defibrillator or cardiac resynchronization therapy defibrillator equipped with iATP algorithm was implanted, we investigated the efficacy and safety of iATP for VT refractory to conventional burst pacing. Eight patients had a total of 17 episodes of iATP therapy after failed conventional burst pacing within 11.2 ± 6.6 months of follow-up. Eleven VT episodes (64.7%) in seven patients (87.5%) were successfully terminated by iATP, and only one patient (12.5%) experienced VT acceleration. iATP might be useful for VTs refractory to conventional burst pacing with a low risk of VT acceleration.     

单根电极VDD起搏器的初步应用（附七例报告）

自１９９４年１～１０月共为７例（完全性房室传导阻滞６例、高度房室传导阻滞１例）病人应用了单电极ＶＤＤ起搏器。术后随诊３～１２（平均６．５±２．５）个月，动态心电图监测全部达到心房同步起搏的目的，其中１例有个别间断性Ｐ波感知差而自动转为ＶＶＩ起搏，但总的Ｐ波感知率在９８％以上。如植入病例经严格选择（窦房功能正常的房室传导阻滞），单电极ＶＤＤ起搏可代替双腔ＤＤＤ起搏。     

生理性起搏临床研究及进展

右心室起搏已被证实同心力衰竭、心房颤动、病死率等有密切关联,促使起搏治疗新一轮的革新。生理性起搏是近来心脏起搏器临床研究的重要方向,目前国内外主要通过优化起搏功能、选择起搏部位最小化心室起搏。以尽可能的生理性起搏,维持整个循环系统的稳定,从而提高患者生活质量并指导起搏器临床应用。     

Comparison of burst versus ramp antitachycardia pacing therapy for ventricular tachycardia: A meta-analysis

Current guidelines recommend at least one attempt of defibrillator antitachycardia pacing (ATP) therapy, showing preference for burst therapy. The objective of this study is to compare ramp versus burst ATP therapy proportion of success and acceleration in treating spontaneous or induced ventricular tachycardia (VT). The review protocol was previously published in PROSPERO. Data synthesis and measures of heterogeneity (I²) was performed by CMA® software v.3 comparing proportions in both groups. Sensitivity analysis was performed as subgroup or meta-regression according to quality, clinical characteristics, and differences in design. Thirteen studies including 30,117 VT episodes in 1672 patients were analyzed. There was no significant difference in the proportion of success between burst and ramp therapy in spontaneous VT (odds ratio = 1.116; 95% confidence interval [CI] = 0.788–1.579; I² = 89%). There was no significant difference in the proportion of success between burst and ramp therapy in induced VT (odds ratio = 0.820; 95% CI = 0.468–1.437; I² = 93%). No significant difference was found in the proportion of acceleration between burst and ramp in spontaneous VT (odds ratio = 0.792; 95% CI = 0.476–1.317; I² = 83%). No significant difference was found in the proportion of acceleration between burst and ramp in induced VT (odds ratio = 1.234; 95% CI = 0.802–1.898; I² = 55%). Sensitivity analysis did not change main results. There is no difference in success or in acceleration proportion between burst or ramp ATP therapy irrespective if the VT was spontaneous or induced. Future implantable cardioverter defibrillator programming guidelines should offer both ATP therapies without preference in one of them.     

In-hospital experience with multiprogrammable implantable antitachycardia/antifibrillation devices

Multiprogrammable, automatic internal defibrillators with (n= 45) and without (n = 15) antitachycardia pacing features wereimplanted in 60 consecutive patients with refractory, malignantventricular tachycardia (VT) (n = 42) or fibrillation (VF) (n= 18). Left ventricular (LV) ejectionfraction wasreduced to39% ± 12% as a result of structural heart disease in56 patients. The complexity of the systems caused no additionalrisks to the surgical procedure or postoperative management.VT/VF detection parameters were individually adjusted to thearrhythmia type (detection cycle length 323 ± 40 ms inpatients with VF vs 405 ± 40 ms for VT patients, P<0.05)and incidence (longer detection periods if frequent nonsustainedVT was also present). Shock energy was reduced in patients withVT as compared to VF(11J vs 24J, P<0.05). Antitachycardiapacing was activated in 19/28 (68%) patients with well toleratedVT. Signal, telemetry, as detected by the device, combined withprogrammability allowed the device to be checked for correctdecisions (these were inappropriate in four patients in threeof whom corrections were non-invasive) prior to discharge. Inconclusion, in the automatic tachyarrhythmia control deviceswe studied, programmability and flexibility appeared to be clinicallysafe and useful. Prolonged observation periods are required,however, to evaluate the true clinical safety and persistentefficacy of device programmability and flexibility.     

Left Heart Pacing—Experience with Several Types of Coronary Vein Leads

Our experience with 121 coronary vein (CV) leads in 116 patients shows that CV leads are the leads of choice for pacing the left ventricle (LV). The information gained from pre-operative venous angiography permits individual selection of the most appropriate lead model for each case. The use of steerable electrophysiology catheters facilitates guide catheter cannulation of the coronary sinus (CS) when the anatomy is difficult and reduces the risk of complications. By selecting the CV lead model most suitable for each individual patient, we achieved successful implantation in 99.1% of patients. In this day and age, epicardial electrodes should be restricted to cases with CS anomalies which make CS cannulation impossible, and to LV lead implantation during heart surgery.     

Termination of refractory ventricular tachycardia by a combination of intravenous sotalol and overdrive ventricular pacing

Right ventricular overdrive pacing is an effective method for termination of ventricular tachycardia. This may be due to alteration in conduction rate, conduction pathways, or refractory periods of myocardial tissue. The procedure can be facilitated by antiarrhythmic drugs which increase tachycardia cycle length. Sotalol possesses beta-blocking action, has been shown to increase duration of action potentials and refractory periods throughout myocardial tissue and accessory pathways, and can suppress and prevent recurrent malignant ventricular arrhythmias. We describe two cases with ventricular tachycardia which were terminated transiently by cardioversion, but were resistant to various antiarrhythmic drugs. Right ventricular overdrive pacing was used in both cases, but was only effective after the administration of intravenous sotalol. We conclude that the unique properties of sotalol may make it especially effective in this context. Caution is required because of the hypotensive and negative inotropic actions of beta blockers, and possible acceleration of ventricular tachycardia by overdrive pacing.