Therapy For Ventricular Tachyarrhythmias Research Articles

Treatment of ventricular tachyarrhythmias and prevention of sudden cardiac death: commentary on the 2016 ESC guideline

The 2016 ESC guideline on prevention and therapy of ventricular tachyarrhythmias and sudden cardiac death present an excellent recommendation and summary for all forms of ventricular tachyarrhythmias in patients with and without structural or electrical heart disease. This includes cardiomyopathies as well as conditions such as proarrhythmia, neurologic/psychaitric disorders, or pregnancy. Some aspects are novel; (1) the guideline emphasizes for the first time genetic work-up in sudden cardiac death victims; (2) for prevention of sudden cardiac death systematic re-evaluation 6-12 weeks after myocardial infarction is recommended; (3) subcutaneous ICD as well as the wearable cardioverter/defibrillator are for the first time included in the guidelines; (4) automatic external defibrillators are recommended for public places; (5) for patients with recurrent ventricular tachyarrhythmias the role of catheter ablation has been upgraded.

Left ventricular sphericity independently predicts appropriate implantable cardioverter-defibrillator therapy

Whether echocardiographic markers of remodeling are associated with ventricular tachyarrhythmias is unknown. The purpose of this study was to determine whether a transthoracic echocardiographic (TTE) marker of spherical left ventricular (LV) remodeling is associated with appropriate implantable cardioverter-defibrillator (ICD) therapy in patients with primary prevention ICDs. From TTE images, we calculated sphericity index (SI), the ratio of biplane LV end-diastolic volume to the volume of a hypothetical sphere with a diameter of the LV end-diastolic length, and examined the relation between SI and therapy for ventricular tachyarrhythmias in 278 patients with primary prevention ICDs and in 50 controls without structural heart disease or ventricular arrhythmias. SI in normal healthy adult subjects and in subjects receiving ICDs was 0.44 ± 0.02 and 0.65 ± 0.04, respectively (P <.001). Median time to first appropriate ICD therapy was significantly shorter in ICD patients with SI in the upper vs lower 50% of SI values (1.40 vs 2.38 years, P = .02 for conventional ICD patients; 1.54 vs 2.65 years, P = .02 for cardiac resynchronization therapy-defibrillator [CRT-D] patients). In multivariable Cox regression analysis, SI in the upper 50% was independently associated with appropriate ICD therapy after multivariable adjustment (hazard ratio 2.2, P = .03 for ICD cohort; hazard ratio 4.4, P = .01 for CRT-D cohort). SI was not associated with total mortality in either cohort. SI is associated with appropriate ICD therapy, but not total mortality, in patients receiving primary prevention ICDs. These observations suggest spherical LV remodeling may predispose to ventricular arrhythmias. Furthermore, SI appears to add predictive accuracy for appropriate ICD therapy in patients with reduced ejection fraction.

Myocardial scar characteristics based on cardiac magnetic resonance imaging is associated with ventricular tachyarrhythmia in patients with ischemic cardiomyopathy

ObjectivesWe hypothesized that myocardial scar characterization using cardiac magnetic resonance imaging (CMR) may be associated with the occurrence of ventricular tachyarrhythmia (VT), appropriate implantable cardioverter-defibrillator (ICD) therapy and mortality. BackgroundSince a minority of patients with prophylactic ICD implantation receive appropriate ICD therapy, there is a need for more effective risk stratification for primary prevention in patients with ischemic cardiomyopathy. Methods and resultsIn 99 patients with ischemic cardiomyopathy, CMR was performed prior to ICD implantation. We assessed if CMR indices (cardiac mass, LVEF) and CMR scar characteristics (infarct core mass, peri-infarction mass and the ratio's between left ventricular mass, infarct core mass and peri-infarction mass) were associated with outcome. The primary endpoint was sustained VT and/or appropriate ICD therapy. The secondary endpoint was all-cause mortality. During a median follow-up of 5.4years (IQR 4.5–6.6years), 34 patients reached the primary end-point (17 appropriate ICD shocks) and 26 patients died. In multivariable Cox regression analysis, peri-infarction to core-infarction ratio (HR 2.01, 95%CI: 1.17–3.44, p=0.01) was independently and significantly associated with the primary endpoint, whereas NYHA-class and lower LVEF were not. Conversely, age (HR 1.06, 95% CI: 1.01–1.12, p=0.02) and lower LVEF (HR 0.95, 95% CI: 0.91–1.00, p=0.04) were independently associated with all-cause mortality, mainly due to heart failure. ConclusionA relatively large peri-infarction mass is associated with sustained VT and/or appropriate ICD therapy, whereas age and lower LVEF are associated with mortality. CMR based tissue characterization could aid in the prediction of specific outcome measures and in clinical decision making.

Ventricular Tachyarrhythmias and Mortality in Patients With an Implantable Cardioverter Defibrillator

We examined whether depression is independently associated with implantable cardioverter defibrillator (ICD) therapy for ventricular tachyarrhythmias and mortality. A cohort of 430 consecutive patients with a first-time ICD (79% men; mean [standard deviation] age = 57.8 [12.1] years) completed the Hospital Anxiety and Depression Scale 1 day before implantation. During follow-up, the ICD was interrogated at 3-month intervals. Cox proportional hazard regression analyses were used to examine the impact of depression on time to first appropriate ICD therapy and all-cause mortality during a median follow-up period of 3.8 years. Of all patients, 108 (25.1%) were depressed. Depression was not associated with time to first appropriate ICD therapy (unadjusted hazard ratio [HR] = 1.07, 95% confidence interval [CI] = 0.73-1.56). However, depression was associated with an increased risk for all-cause mortality (unadjusted HR = 2.18, 95% CI = 1.36-3.49). Depression remained independently associated with all-cause mortality (HR = 1.94, 95% CI = 1.06-3.54, p = .031), after adjusting for demographic and clinical characteristics. Patients who remained depressed during the first 3 months after implantation were at greatest risk for dying (HR = 2.88, 95% CI = 1.29-6.45, p = .010). The current study showed that depression at the time of implant is not associated with time to first appropriate ICD therapy but almost doubled the risk for all-cause mortality in patients with an ICD. Patients with persistent depression during the first 3 months after implantation face the greatest risk of dying. Current evidence indicates that multifactorial interventions are likely to be the most successful in terms of reducing distress. Whether this translates into enhanced survival has yet to be determined.

Do we need defibrillation threshold testing?: A pilot study

Defibrillation threshold testing (DFT) is a standard procedure during implantable cardioverter defibrillator (ICD) implantation, however, it is not without risks. We compared the one-year follow-up period in ICD-implanted patients, with and without DFT performed during implantation, for preventive indication in regard to appropriate and inappropriate ICD detection and therapy. One group consisted of 20 patients without DFT; another was comprised of 20 patients where DFT had been performed. There was no difference in the development of ventricular tachyarrhythmias between the groups. Appropriate therapy of ICD was 100%. DFT is not a predictor for successful ICD detection and therapy of ventricular tachyarrhythmias.

Subcutaneous Implantable Cardioverter-Defibrillator Technology

The advent of subcutaneous implantable cardioverter-defibrillator (ICD) systems represents a paradigm shift for the detection and therapy of ventricular tachyarrhythmias. Despite advances in transvenous lead technology, problems remain that notably include requirement for technical expertise; periprocedural complications during implantation and explantation; and long-term lead failure. Although subcutaneous ICD systems may mitigate some of these risks, they provide new shortcomings, such as inability to provide pacing therapy for bradyarrhythmias, ventricular tachyarrhythmias, and cardiac resynchronization. Ongoing clinical evaluation and development are required before the role of subcutaneous ICDs as an adjunctive or primary therapy can be defined. This article examines studies investigating the subcutaneous ICD and discusses its possible advantages and disadvantages as compared with current transvenous ICD systems.

Subcutaneous Implantable Cardioverter-Defibrillator Technology.

The advent of subcutaneous implantable cardioverter-defibrillator (ICD) systems represents a paradigm shift for the detection and therapy of ventricular tachyarrhythmias. Despite advances in transvenous lead technology, problems remain that notably include requirement for technical expertise; periprocedural complications during implantation and explantation; and long-term lead failure. Although subcutaneous ICD systems may mitigate some of these risks, they provide new shortcomings, such as inability to provide pacing therapy for bradyarrhythmias, ventricular tachyarrhythmias, and cardiac resynchronization. Ongoing clinical evaluation and development are required before the role of subcutaneous ICDs as an adjunctive or primary therapy can be defined. This article examines studies investigating the subcutaneous ICD and discusses its possible advantages and disadvantages as compared with current transvenous ICD systems.

AB9-6: Mechanisms of unpinning and termination of ventricular tachycardia

High energy defibrillation shock is the only therapy for ventricular tachyarrhythmias. We have shown theoretically that a properly timed low energy pulse can unpin and terminate anatomically defined reentry. This unpinning mechanism could potentially result in a significant reduction in defibrillation energy.

Mechanisms of unpinning and termination of ventricular tachycardia

High-energy defibrillation shock is the only therapy for ventricular tachyarrhythmias. However, because of adverse side effects, lowering defibrillation energy is desirable. We investigated mechanisms of unpinning, destabilization, and termination of ventricular tachycardia (VT) by low-energy shocks in isolated rabbit right ventricular preparations (n = 22). Stable VT was initiated with burst pacing and was optically mapped. Monophasic "unpinning" shocks (10 ms) of different strengths were applied at various phases throughout the reentry cycle. In 8 of 22 preparations, antitachycardia pacing (ATP: 8-20 pulses, 50-105% of period, 0.8-10 mA) was also applied. Termination of reentry by ATP was achieved in only 5 of 8 preparations. Termination by unpinning occurred in all 22 preparations. Rayleigh's test showed a statistically significant unpinning phase window, during which reentry could be unpinned and subsequently terminated with E80 (magnitude at which 80% of reentries were unpinned) = 1.2 V/cm. All reentries were unpinned with field strengths < or = 2.4 V/cm. Unpinning was achieved by inducing virtual electrode polarization and secondary sources of excitation at the core of reentry. Optical mapping revealed the mechanisms of phase-dependent unpinning of reentry. These results suggest that a 20-fold reduction in energy could be achieved compared with conventional high-energy defibrillation and that the unpinning method may be more effective than ATP for terminating stable, pinned reentry in this experimental model.

Use-dependent electrophysiologic effects of DL-sotalol and modulation by isoproterenol in the human ventricle.

The interaction between dl-sotalol and isoproterenol on the ventricular effective refractory period (VERP) and conduction were examined in an electrophysiologic study of 9 patients at drug-free baseline, after 14 days of dl-sotalol administration (320 mg/day), and after the administration of isoproterenol. In all 9 patients, ventricular tachyarrhythmia could not be induced after dl-sotalol treatment. Isoproterenol was administered as a loading dosage of 0.025 microgram/kg for 5 min with a maintenance dosage of 0.0025 microgram/kg/min. The VERP and the QRS duration were determined at paced cycle lengths of 600, 400 and 300 msec. DL-sotalol and dl-sotalol + isoproterenol had no effect on ventricular conduction at the three cycle lengths. The VERP was significantly prolonged after dl-sotalol treatment at paced cycle lengths of 600 (241 +/- 16 to 302 +/- 28 msec, p < 0.001), 400 (223 +/- 21 to 280 +/- 23 msec, p < 0.001) and 300 msec (202 +/- 16 to 256 +/- 24 msec, p < 0.005), but there was a parallel shift of the VERP, suggesting the absence of use-dependent effects on the VERP. The dl-sotalol-induced VERP prolongation was partially reversed by isoproterenol, but it remained significantly prolonged above baseline values at paced cycle lengths of 600 (241 +/- 16 to 281 +/- 18 msec, p < 0.01), 400 (223 +/- 21 to 258 +/- 20 msec, p < 0.01) and 300 msec (202 +/- 16 to 247 +/- 22 msec, p < 0.01). The shortening of the VERP was greater at longer basic cycle lengths (600 and 400 msec) than at the shorter paced cycle length (300 msec, p < .05), but the percentage increase of the VERP was similar at the three basic cycle lengths of 600 (16%), 400 (15%) and 300 (20%) msec, indicating the lack of reverse use-dependency. The absence of reverse use-dependency of dl-sotalol on the VERP, even after isoproterenol administration, may be beneficial in the therapy of ventricular tachyarrhythmias and may account in part for the high efficacy of this drug.

Long-term Follow-up of Patients Treated with Implantable Cardioverter Defibrillators in a Danish Centre: Occurrence of ICD Therapy and Patient Survival

The aim of the this prospective follow-up study was to evaluate long-term survival and implantable cardioverter-defibrillator (ICD) therapy for ventricular tachyarrhythmias in patients treated with an ICD in a Danish centre. A total of 140 consecutive patients (112 men), of which 70.7% had coronary artery disease, received an ICD at Skejby University Hospital between March 1989 and October 1996. Mean age was 55.6 ± 14.6 years (range 14–78 years). After implantation, 136 of the patients were followed for a median (range) of 17.7 (0.4–74.1) months. Survival, mode of death and incidence of appropriate ICD therapy and therapy due to potential life-threatening ventricular tachyarrhythmia were the main outcome measures. Kaplan-Meier plots representing total survival, cardiac death, sudden cardiac death and first episode of ICD therapy are presented. After 1, 2, 3 and 4 years, respectively, the cumulative incidences of death were 9, 18, 20 and 24%, of cardiac death 4, 11, 14 and 18%, and of sudden cardiac death 2, 3, 6 and 6%. The cumulative incidences of appropriate therapy after 1, 2, 3 and 4 years were 47, 56, 66 and 80%, respectively. The cumulative incidences of cardiac death after the first episode of appropriate therapy were 9, 11, 15 and 20% after 1, 2, 3 and 4 years, respectively. The occurrence of ICD therapy and patient survival in the present study population treated with ICD at a Danish centre was comparable to results published previously from other larger centres. The rate of sudden cardiac death was low and most of our patients received appropriate ICD therapy during follow-up, indicating correct patient selection and probable benefit of the ICD device.

Surgical therapy of ventricular tachyarrhythmias in patients with coronary artery disease.

Surgical therapy of ventricular tachyarrhythmias in patients with coronary artery disease.

Cost and efficacy analysis in the ESVEM trial: Implications for diagnosis and therapy for ventricular tachyarrhythmias

Physicians must now consider the likely cost of management decisions as well as the expected effects on patient outcome. Cost-ascertainment studies identify and contrast the cost of therapies, and cost-effectiveness analysis compares the additional cost of a therapy with its additional effect on survival and quality of life. This article reviews the principles of cost-ascertainment and cost-effectiveness analysis and then presents the cost of initial and follow-up care in Electrophysiologic Study Versus Electrocardiographic Monitoring (ESVEM) trial. Finally, the cost-effectiveness of therapy guided by electrophysiologic study or Holter monitoring and of sotalol versus other drugs is reviewed, and implications for future studies are discussed.

Pharmacologic Therapy in Patients with Ventricular Tachyarrhythmias

Table 5 can be used as framework for a summary of the previous discussion on pharmacologic therapy for ventricular tachyarrhythmias. The system for grading the severity of symptoms of ventricular tachyarrhythmias, previously presented in Table 3, is arranged vertically along the left side of Table 5. Horizontally across the top, patients are grouped according to the presence or absence of structural heart disease, and those with structural heart disease are further dichotomized according to left ventricular ejection fraction. As can be seen, patients with class I symptoms should not be treated whenever possible, although in patients with reduced left ventricular function (especially coronary heart disease), an argument can be made for empirical treatment with beta-adrenoceptor blocking agents whenever possible. Patients with class II symptoms can be treated empirically with beta-adrenoceptor blocking agents. Other antiarrhythmic agents may be safer when there is no underlying structural heart disease, but this has not been proved. The use of antiarrhythmic agents other than beta-adrenoceptor blocking agents in patients with class II symptoms should probably be guided and monitored by ambulatory electrocardiographic recording and exercise tolerance testing. In the patient with hemodynamically stable ventricular tachycardia, electrophysiologic-guided therapy is probably preferable whenever possible. Encainide, flecainide, and similar drugs should be avoided when there is a possibility of residual ventricular premature depolarizations of three or more per hour. Some uncertainty remains concerning the treatment of patients with class III and class IV symptoms and no structural heart disease. Some patients may fall into a specific group that is very responsive to drug therapy. These patients should probably be treated like other patients with class III and class IV symptoms. Electrophysiologic testing may be helpful. When such patients have a reproducibly induced sustained ventricular tachyarrhythmia, it is likely that antiarrhythmic drug therapy will render the arrhythmia noninducible, and that they will do well while receiving long-term pharmacologic therapy. When such patients do not have a reproducibly induced sustained ventricular tachyarrhythmia, the main controversy is whether therapy is needed. If it is decided that such a patient needs therapy, the choice is usually between empiric amiodarone and an ICD, although catheter ablation may be helpful in selected instances. Patients with class III and class IV symptoms who have structural heart disease require therapy. Although this continues to be an evolving area of investigation, for many of these patients, the initial attempt at therapy should be pharmacologic.(ABSTRACT TRUNCATED AT 400 WORDS)