CRT Survey II: a European Society of Cardiology survey of cardiac resynchronisation therapy in 11 088 patients-who is doing what to whom and how?

BACKGROUND

Cardiac resynchronisation therapy (CRT) reduces morbidity and mortality in appropriately selected patients with heart failure and is strongly recommended for such patients by guidelines. A European Society of Cardiology (ESC) CRT survey conducted in 2008-2009 showed considerable variation in guideline adherence and large individual, national and regional differences in patient selection, implantation practice and follow-up. Accordingly, two ESC associations, the European Heart Rhythm Association and the Heart Failure Association, designed a second prospective survey to describe contemporary clinical practice regarding CRT.

METHODS AND RESULTS

A survey of the clinical practice of CRT-P and CRT-D implantation was conducted from October 2015 to December 2016 in 42 ESC member countries. Implanting centres provided information about their hospital and CRT service and were asked to complete a web-based case report form collecting information on patient characteristics, investigations, implantation procedures and complications during the index hospitalisation. The 11 088 patients enrolled represented 11% of the total number of expected implantations in participating countries during the survey period; 32% of patients were aged ≥75 years, 28% of procedures were upgrades from a permanent pacemaker or implantable cardioverter-defibrillator and 30% were CRT-P rather than CRT-D. Most patients (88%) had a QRS duration ≥130 ms, 73% had left bundle branch block and 26% were in atrial fibrillation at the time of implantation. Large geographical variations in clinical practice were observed.

CONCLUSION

CRT Survey II provides a valuable source of information on contemporary clinical practice with respect to CRT implantation in a large sample of ESC member states. The survey permits assessment of guideline adherence and demonstrates variations in patient selection, management, implantation procedure and follow-up strategy.

Radiofrequency ablation of focal atrial tachycardia: Benefit of electroanatomical mapping over conventional mapping

BACKGROUND

Catheter ablation is a proven therapy of focal atrial tachycardia. However limited information is available about the additional value of electroanatomical over conventional mapping methods for this specific arrhythmia.

METHODS

Consecutive catheter ablation procedures of FAT were analyzed in two cardiology centres. Only conventional mapping was used in 30 of the 60 procedures whereas additionally CARTO mapping was performed in another 30 procedures. Acute, six-month success rate, and procedural data were analyzed.

RESULTS

Localization of ectopic foci is congruent with previously published data. There was no statistically significant difference between procedure time and fluoroscopy time using additionally CARTO mapping, compared to conventional mapping only. Acute success rate was higher in procedures guided by CARTO mapping than in procedures based on conventional mapping (27/30 vs. 18/30, p = 0.0081). During the 6-month follow-up period there was a better outcome (p = 0.045) in case of CARTO guided procedures (success: 11 cases, partial success: 12 cases, failure: 4 cases) compared to conventional mapping (success: 4 cases, partial success: 18 cases, failure: 7 cases).

CONCLUSIONS

Catheter ablation of focal atrial tachycardias using the CARTO electroanatomical mapping system seems to provide higher acute and 6-month success rate compared to ablation using conventional mapping methods only.

First prospective, multi-centre clinical experience with a novel left ventricular quadripolar lead

AIMS

Cardiac resynchronization therapy (CRT) is sometimes complicated by elevated pacing thresholds and phrenic nerve stimulation (PNS), both of which may require that the coronary sinus lead be repositioned. The purpose of this study was to evaluate the performance of a novel quadripolar electrode lead and cardiac resynchronization therapy-defibrillator (CRT-D) device that enables electrical repositioning, potentially obviating a lead reposition procedure.

METHODS AND RESULTS

Patients indicated for CRT were enrolled and received a quadripolar electrode lead and CRT-D device (Quartetmodel 1458Q and Promote Q; St Jude Medical, Sylmar, CA, USA). Electrical data, and the presence of PNS during pacing from each left ventricular (LV) configuration, were documented at pre-hospital discharge and at 1 month. Seventy-five patients were enrolled and 71 were successfully implanted with a Quartetlead. Electrical measurements were stable over the follow-up period. Ninety-seven per cent (64 of 66) of patients had one or more programmable configurations with a threshold < 2.5 V and no PNS vs. 86% (57 of 66) if only conventional bipolar configurations were considered. Physicians were able to use the increased programming options to manage threshold changes and PNS.

CONCLUSION

The new quadripolar electrode LV lead provides more programming options to address common problems faced when managing CRT patients. Electrical measurements from new vectors are comparable with conventional configurations. Furthermore, 11% of patients in the study suffered PNS on all conventional bipolar vectors.

[Clinical profile of the new antiarrhythmic drug dronedarone]

The new antiarrhythmic drug dronedarone (SR 33 589) is a benzofuran derivative structurally similar to amiodarone, however is noniodinated. The additional methansulfonylgroup renders it less lipophilic, with a substantially shorter half-life, compared to the parent compound. The electrophysiological properties of both agents are similar with inhibition of Na+, K+, and Ca++ currents (all Vaughan-Williams classes). The agent has been evaluated in a large clinical study program. The daily dose of dronedarone 800 mg has been shown (DAFNE) to be effective and well tolerated. In two design-identical randomised clinical trials (EURIDIS and ADONIS trial) the efficacy of dronedarone to maintain sinus rhythm in patients with chronic atrial fibrillation/flutter was shown to be clearly superior to placebo. The ERATO study showed the rate control properties of dronedarone. In the ATHENA morbidity/mortality study, the combined endpoint death or hospitalisation due to cardiovascular events occurred significantly less often in the dronedarone group compared to the placebo group. Particularly due to its beneficial effects on clinical outcomes such as cardiovascular hospitalizations and death in the context of high tolerability dronedarone appears to be a promising new antiarrhythmic compound.

Assessment of microvolt T-wave alternans in high-risk patients with the congenital long-QT syndrome

BACKGROUND

Microvolt T-wave alternans (MTWA) has been used for arrhythmogenic risk stratification in cardiac disease conditions associated with increased risk of sudden cardiac death. Macroscopic T-wave alternans has been observed in patients with congenital long-QT syndrome (LQTS). The role of MTWA testing in patients with LQTS has not been established.

OBJECTIVE

To determine the diagnostic value of MTWA testing in high-risk patients with LQTS.

METHODS AND RESULTS

We assessed MTWA in 10 consecutive LQTS index patients who survived cardiac arrest or had documented torsade de pointes tachycardia and 6 first-degree family members with congenital LQTS which had been genotyped in 13 of 16 subjects (7 index patients, 6 family members). No LQTS-causing mutation was identified in 3 index patients with overt QT prolongation. MTWA was assessed during standardized bicycle exercise testing using the spectral method and yielded negative (n = 8) or indeterminate (n = 2) results in index patients, respectively. Similarly, all first-degree family members tested MTWA negative except for one indeterminate result. Two genotype positive family members could not be tested (two children-4 and 9 years of age).

CONCLUSION

In patients with congenital LQTS, free from structural heart disease and with a history of life-threatening cardiac arrhythmias, assessment of MTWA does not yield diagnostic value. Hence, determination of MTWA in lower risk LQTS patients without spontaneous arrhythmic events is likely not to be useful for arrhythmia risk stratification.

Biventricular pacing does not affect microvolt T-wave alternans in heart failure patients

BACKGROUND

Microvolt T-wave alternans (MTWA) is a valuable tool for stratification of patients at risk for sudden death and has recently been approved for this purpose by Medicare. Although right atrial (RA) pacing has been applied for MTWA testing, the effects of other pacing modalities on MTWA have not been systematically studied. Accordingly, it is unknown whether biventricular (BiV) pacing might influence MTWA test results.

OBJECTIVE

This study sought to investigate effects of BiV pacing in comparison with other pacing modalities.

METHODS

Congestive heart failure patients (n = 30) receiving cardiac resynchronization therapy were included, and a systematic step-up pacing protocol was performed via the implanted cardioverter-defibrillator.

RESULTS

Of the overall 120 MTWA tests performed, 67 (56%) were nonnegative. Nonnegative MTWA test results were observed in 18 patients (60%) during RA stimulation, whereas 17 (57%), 15 (50%), and 17 test results (57%) were nonnegative during right ventricular (RV), left ventricular (LV), and BiV pacing, respectively. Seven (23%) patients were MTWA negative for all pacing sites. Results of MTWA assessment during RA pacing were concordant with results obtained with RV pacing in 25 (83%) patients (kappa = 0.66, P = .0003), to LV pacing in 21 (70%) patients (kappa = 0.4, P = .025), and to BiV pacing in 25 (83%) patients (kappa = 0.66, P = .0003). Positive and negative predictive values of nonnegative MTWA test results obtained during RA pacing for a similar result obtained with RV pacing were 88% and 76%. Respective values were similar for other pacing modalities (80% and 60% for LV; 88% and 76% for BiV pacing).

CONCLUSION

There is a high level of concordance between MTWA test results obtained during RA pacing and other pacing modalities, and MTWA assessment seems not to be influenced by BiV stimulation in congestive heart failure patients. In general, BiV pacing does not seem to affect an arrhythmogenic substrate as detected by MTWA testing.

[Pharmacological therapy for ventricular arrhythmias: evidence for current treatment strategies and perspectives for the future]

This review summarizes the current status of pharmacological therapy for ventricular arrhythmias in symptomatic patients. The selection of specific drugs for this indication is highly dependent on the underlying heart disease. In primary prevention of sudden death, antiarrhythmic agents do not play a role--except betareceptor antagonists. Similarly, in patients treated for secondary prevention of cardiac arrest or hemodynamically symptomatic ventricular tachycardia, the implantable defibrillator constitutes the therapy of choice with hardly any role left for antiarrhythmic drugs. An emerging role for antiarrhythmic drug therapy is represented by the concomitant pharmacological treatment in ICD recipients who experience shocks from their devices (hybrid therapy). Several randomized clinical trials have recently evaluated this issue and permit an evidence-based treatment strategy. Currently, most patients receive sotalol or amiodarone for hybrid therapy with azimilide as a potential new class III antiarrhythmic drug for this treatment indication.

External cardioversion of atrial fibrillation in patients with implanted pacemaker or cardioverter-defibrillator systems: a randomized comparison of monophasic and biphasic shock energy application

AIMS

External cardioversion (ECV) of atrial fibrillation (AF) may damage implanted pacemaker and cardioverter-defibrillator (ICD) systems. This prospective study evaluated the safety and efficacy of ECV comparing mono- to biphasic shock waveforms in patients with implanted rhythm devices.

METHODS AND RESULTS

Patients with pacemaker or ICD systems and an indication for ECV were randomized to receive mono- or biphasic shocks. Systems were tested immediately before and after ECV, 1 h and 1 week later with respect to device and lead integrity. Forty-four patients (71 +/- 10 years, 31 male; 29 pacemakers, 12 ICDs, three cardiac resynchronization systems) underwent ECV with antero-posterior paddle orientation (monophasic in 21 and biphasic in 23 patients). Pacing impedances were reduced immediately after ECV (atrial 402-392 ohm, P < 0.001; ventricular 517-496 ohm, P = 0.001) and returned to baseline values within 1 week. Ventricular sensing was reduced immediately after ECV (12.4-11.6 mV, P = 0.004). There was no device or lead dysfunction in any patient. ECV was successful in 42/44 patients (95%), cumulative energy was significantly lower for biphasic compared with monophasic shocks (P = 0.001).

CONCLUSION

ECV for AF seems to be safe and effective in patients with implanted rhythm devices.

Recent primary prevention implantable cardioverter defibrillator trials

PURPOSE OF THE REVIEW

The aim of this article is to summarize the most relevant findings of recently published trials on prophylactic implantable cardioverter defibrillator therapy.

RECENT FINDINGS

A number of important randomized clinical trials on the efficacy of prophylactic implantable cardioverter defibrillator therapy in patients deemed to be at high risk for ventricular tachyarrhythmias have recently reported their results. Patients with chronic ischemic cardiomyopathy, a long history of heart failure, and an ejection fraction of 0.30 or below benefit from preventive device therapy and are thus candidates for prophylactic defibrillator implantation. For this purpose, a single chamber device appears to be appropriate since there have been no prospective studies showing convincing clinical benefit by adding an atrial lead. Prophylactic implantable cardioverter defibrillator therapy should not be used in patients with recent myocardial infarction. There is convincing evidence from one trial that benefit from the defibrillator in coronary patients accrue after a considerable time has elapsed from the most recent infarct, presumably at least 6 months or perhaps longer. Finally, in patients with chronic dilated non-ischemic cardiomyopathy and a left ventricular ejection fraction of 0.35 or below, there is also benefit from prophylactic implantable cardioverter defibrillator therapy.

SUMMARY

Taken together, these trials allow an evidence-based approach to primary prevention of sudden cardiac death in patients with both ischemic and non-ischemic cardiomyopathy.

Efficacy and Safety of ICD Therapy in a Population of Elderly Patients Treated with Optimal Background Medication

INTRODUCTION

Implantable cardioverter-defibrillator (ICD) therapy has been shown to improve survival in patients with structural heart disease and at high risk for life threatening ventricular arrhythmias. Whether elderly patients benefit from device therapy in a similar way as younger patients is largely unknown.

METHODS

We retrospectively analyzed data from 375 consecutive ICD recipients with structural heart disease. Patients were divided into two groups, younger than 70 years at time of ICD implantation (group 1) or 70 years or older (group 2). Main outcome measures were time to death from any cause and time from first appropriate ICD therapy to death.

RESULTS

Group 1 and 2 patients were comparable with respect to clinical presentation and average follow-up duration. In the elderly patient group, 78% received an ICD for secondary prevention versus 63% in group 1 (p = 0.007). During a mean follow-up period of 26.5 +/- 18.1 months, there was no significant difference in overall mortality among the two groups: 47 patients died, 34 (12.5%) of group 1 versus 13 (12.7%) of group 2. The average time to death was 28.4 +/- 16.7 vs 30.4 +/- 22.1 months after device implantation, respectively (p = ns). There was no difference in time from device implantation to first adequate ICD therapy and time from first appropriate ICD therapy to death among the two groups (p = ns). Device associated complications were comparable in both groups.

CONCLUSIONS

Elderly ICD recipients had comparable survival rates and appropriate use of the ICD compared to younger individuals.

Prevention of Sudden Cardiac Death

Sudden cardiac death (SCD), presumably because of ventricular tachyarrhythmias, remains one of the major challenges of contemporary cardiology. Major randomized controlled trials conducted in patients with coronary artery disease (CAD) with the aim of primary prevention of SCD are providing insights. Several large-scale studies have demonstrated that treatment with beta-blockers, angiotensin-converting enzyme inhibitors, aldosterone antagonists, and statins results not only in a reduction in all-cause mortality but specifically also in SCD. On top of this optimized pharmacological therapy, implantable cardioverter-defibrillators (ICD) further decrease the risk of overall and SCD mortality in carefully selected patient groups. The sum of these trials indicates, however, that the benefit associated with ICD therapy is most prominent in patients with chronic stable CAD. In contrast, patients early after myocardial infarction derive less benefit from ICD treatment, presumably because of a high competing risk of non-arrhythmic cardiovascular death. Optimized pharmacological therapy, together with the ICD, can substantially improve the prognosis of high-risk CAD patients.

Complications due to abandoned noninfected pacemaker leads

Noninfected unwanted pacemaker leads are usually abandoned since the reported complication rate related to them is low. We followed 60 patients with noninfected retained leads, and complication was observed in 12 (20%) of them. Lead migration occurred in 5 patients, skin erosion in 3 patients, venous thrombosis in 2 patients, and muscle stimulation in 2 patients. Management of the complications was a surgical procedure in seven patients, including two cases of open heart surgery, while chronic medical treatment was necessary in the other five patients. The results of this study suggest that complications due to noninfected abandoned leads may not be as rare as it was previously thought and may present a significant morbidity and cost burden. With the lead extraction technique available, the issue of the removal of all unwanted pacemaker leads should be addressed.

Runaway pacemaker syndrome and intermittent nonoutput as manifestations of end of life of a VVI pacemaker

A case of a runaway pacemaker with intermittent nonoutput failure of a VVI Intermedics pacemaker is presented. This is the first report of such a phenomenon in that type of pacemaker with no apparent reason other than approaching battery end-of-life. The reported case warrants a close follow-up of patients with the same type of device.