Gabor Z. Duray

Atrial fibrillation in acute myocardial infarction: a systematic review of the incidence, clinical features and prognostic implications

Atrial fibrillation (AF), the most commonly encountered clinical arrhythmia, often complicates acute myocardial infarction (AMI) with an incidence between 6 and 21%. Predictors of the arrhythmia in the setting of AMI include advanced age, heart failure symptoms, and depressed left ventricular function. The bulk of evidence demonstrates that AF in patients hospitalized for AMI has serious adverse prognostic implications regarding in-hospital, but also long-term mortality. This seems to apply for all patient populations studied without significant differences related to the treatment of AMI (i.e. no reperfusion therapy vs. thrombolysis vs. percutaneous coronary intervention). Mortality is particularly high in patients who have congestive heart failure and/or a reduced left ventricular ejection fraction. Finally, there are persuasive data indicating that AF complicating AMI not only increases the risk for ischaemic stroke during hospitalization but also during follow-up. This seems to apply also for transient AF which has reversed back to sinus rhythm at the time of discharge. These observations emphasize the need for prospective studies evaluating optimal therapeutic approaches for patients with AMI complicated by AF.

A Leadless Intracardiac Transcatheter Pacing System

BACKGROUND A leadless intracardiac transcatheter pacing system has been designed to avoid the need for a pacemaker pocket and transvenous lead. METHODS In a prospective multicenter study without controls, a transcatheter pacemaker was implanted in patients who had guideline-based indications for ventricular pacing. The analysis of the primary end points began when 300 patients reached 6 months of follow-up. The primary safety end point was freedom from system-related or procedure-related major complications. The primary efficacy end point was the percentage of patients with low and stable pacing capture thresholds at 6 months (≤2.0 V at a pulse width of 0.24 msec and an increase of ≤1.5 V from the time of implantation). The safety and efficacy end points were evaluated against performance goals (based on historical data) of 83% and 80%, respectively. We also performed a post hoc analysis in which the rates of major complications were compared with those in a control cohort of 2667 patients with transvenous pacemakers from six previously published studies. RESULTS The device was successfully implanted in 719 of 725 patients (99.2%). The Kaplan-Meier estimate of the rate of the primary safety end point was 96.0% (95% confidence interval [CI], 93.9 to 97.3; P<0.001 for the comparison with the safety performance goal of 83%); there were 28 major complications in 25 of 725 patients, and no dislodgements. The rate of the primary efficacy end point was 98.3% (95% CI, 96.1 to 99.5; P<0.001 for the comparison with the efficacy performance goal of 80%) among 292 of 297 patients with paired 6-month data. Although there were 28 major complications in 25 patients, patients with transcatheter pacemakers had significantly fewer major complications than did the control patients (hazard ratio, 0.49; 95% CI, 0.33 to 0.75; P=0.001). CONCLUSIONS In this historical comparison study, the transcatheter pacemaker met the prespecified safety and efficacy goals; it had a safety profile similar to that of a transvenous system while providing low and stable pacing thresholds. (Funded by Medtronic; Micra Transcatheter Pacing Study ClinicalTrials.gov number, NCT02004873.).

New algorithm using only lead aVR for differential diagnosis of wide QRS complex tachycardia

BACKGROUND We recently reported an ECG algorithm for differential diagnosis of regular wide QRS complex tachycardias that was superior to the Brugada algorithm. OBJECTIVE The purpose of this study was to further simplify the algorithm by omitting the complicated morphologic criteria and restricting the analysis to lead aVR. METHODS In this study, 483 wide QRS complex tachycardias [351 ventricular tachycardias (VTs), 112 supraventricular tachycardias (SVTs), 20 preexcited tachycardias] from 313 patients with proven diagnoses were prospectively analyzed by two of the authors blinded to the diagnosis. Lead aVR was analyzed for (1) presence of an initial R wave, (2) width of an initial r or q wave >40 ms, (3) notching on the initial downstroke of a predominantly negative QRS complex, and (4) ventricular activation-velocity ratio (v(i)/v(t)), the vertical excursion (in millivolts) recorded during the initial (v(i)) and terminal (v(t)) 40 ms of the QRS complex. When any of criteria 1 to 3 was present, VT was diagnosed; when absent, the next criterion was analyzed. In step 4, v(i)/v(t) >1 suggested SVT, and v(i)/v(t) < or =1 suggested VT. RESULTS The accuracy of the new aVR algorithm and our previous algorithm was superior to that of the Brugada algorithm (P = .002 and P = .007, respectively). The aVR algorithm and our previous algorithm had greater sensitivity (P <.001 and P = .001, respectively) and negative predictive value for diagnosing VT and greater specificity (P <.001 and P = .001, respectively) and positive predictive value for diagnosing SVT compared with the Brugada criteria. CONCLUSION The simplified aVR algorithm classified wide QRS complex tachycardias with the same accuracy as standard criteria and our previous algorithm and was superior to the Brugada algorithm.

Early performance of a miniaturized leadless cardiac pacemaker: the Micra Transcatheter Pacing Study

Aims Permanent cardiac pacing is the only effective treatment for symptomatic bradycardia, but complications associated with conventional transvenous pacing systems are commonly related to the pacing lead and pocket. We describe the early performance of a novel self-contained miniaturized pacemaker. Methods and results Patients having Class I or II indication for VVI pacing underwent implantation of a Micra transcatheter pacing system, from the femoral vein and fixated in the right ventricle using four protractible nitinol tines. Prespecified objectives were >85% freedom from unanticipated serious adverse device events (safety) and <2 V 3-month mean pacing capture threshold at 0.24 ms pulse width (efficacy). Patients were implanted (n = 140) from 23 centres in 11 countries (61% male, age 77.0 ± 10.2 years) for atrioventricular block (66%) or sinus node dysfunction (29%) indications. During mean follow-up of 1.9 ± 1.8 months, the safety endpoint was met with no unanticipated serious adverse device events. Thirty adverse events related to the system or procedure occurred, mostly due to transient dysrhythmias or femoral access complications. One pericardial effusion without tamponade occurred after 18 device deployments. In 60 patients followed to 3 months, mean pacing threshold was 0.51 ± 0.22 V, and no threshold was ≥2 V, meeting the efficacy endpoint (P < 0.001). Average R-wave was 16.1 ± 5.2 mV and impedance was 650.7 ± 130 ohms. Conclusion Early assessment shows the transcatheter pacemaker can safely and effectively be applied. Long-term safety and benefit of the pacemaker will further be evaluated in the trial. Clinical Trial Registration ClinicalTrials.gov ID NCT02004873.

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.

Complications due to abandoned noninfected pacemaker leads.

BÖHM, Á., et al.: 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.

Implantable cardioverter-defibrillator lead disintegration at the level of the tricuspid valve

i s p n s l e v F t C t b v Lead-related complications are among the most important otential complications requiring reoperation in recipients of n implantable cardioverter-defibrillator (ICD). Lead durability nd integrity depend on several factors, such as lead design, ead material, and mechanical stress. More than half of all lead omplications are insulation defects, most frequently due to ubclavian crush syndrome, abrasion of the lead by the ICD enerator, or abrasian of the lead at the level of lead fixation. Analysis of the stored electrograms from patient report-

Complications leading to surgical revision in implantable cardioverter defibrillator patients: Comparison of patients with single-chamber, dual-chamber, and biventricular devices

AIMS Implantable cardioverter defibrillator (ICD) technology has become more complex, particularly with respect to biventricular resynchronization devices. The incidence of hardware-related complications in single (SC)-, dual (DC)-, and triple (BiV)-chamber devices requiring surgical revision has not been investigated systematically. METHODS AND RESULTS We analysed data from consecutive ICD recipients implanted between January 2000 and December 2007 with respect to the need of surgical re-intervention for device- or lead-related complications. Generator exchanges due to normal battery depletion were not considered. From 816 patients (81% male, 69% ischaemic cardiomyopathy, 48% secondary prevention ICDs) followed for 31 +/- 24 months (2118 cumulative patient-years), 98 patients underwent 110 revisions (5.2% per patient-year). Complications included lead-related revision procedures in 81 cases and generator-related problems in 29 cases. The annual incidence of surgical revision due to complications was 11.8% in BiV compared with 4.9% in SC and 4.1% in DC patients (P = 0.002). This higher revision rate was mainly caused by lead-related complications. Implantation of a BiV system was an independent risk factor of the need for surgical revision (relative risk 2.37, 95% confidence interval 1.38-4.04). CONCLUSION Even with long-lasting operator experience, complications requiring surgical revision remain a clinically important problem of ICD therapy. The incidence of complications is significantly higher in BiV resynchronization devices than in SC and DC systems.

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.

The rationale and design of the Micra Transcatheter Pacing Study: Safety and efficacy of a novel miniaturized pacemaker

AIMS Recent advances in miniaturization technologies and battery chemistries have made it possible to develop a pacemaker small enough to implant within the heart while still aiming to provide similar battery longevity to conventional pacemakers. The Micra Transcatheter Pacing System is a miniaturized single-chamber pacemaker system that is delivered via catheter through the femoral vein. The pacemaker is implanted directly inside the right ventricle of the heart, eliminating the need for a device pocket and insertion of a pacing lead, thereby potentially avoiding some of the complications associated with traditional pacing systems. METHODS AND RESULTS The Micra Transcatheter Pacing Study is currently undergoing evaluation in a prospective, multi-site, single-arm study. Approximately 720 patients will be implanted at up to 70 centres around the world. The study is designed to have a continuously growing body of evidence and data analyses are planned at various time points. The primary safety and efficacy objectives at 6-month post-implant are to demonstrate that (i) the percentage of Micra patients free from major complications related to the Micra system or implant procedure is significantly higher than 83% and (ii) the percentage of Micra patients with both low and stable thresholds is significantly higher than 80%. The safety performance benchmark is based on a reference dataset of 977 subjects from 6 recent pacemaker studies. CONCLUSIONS The Micra Transcatheter Pacing Study will assess the safety and efficacy of a miniaturized, totally endocardial pacemaker in patients with an indication for implantation of a single-chamber ventricular pacemaker. CLINICALTRIALSGOV REGISTRATION ID NCT02004873.