Case Report of the Safety Assessment of Transcranial Magnetic Stimulation Use in a Patient With Cardiac Pacemaker: To Pulse or Not to Pulse?

BACKGROUND: Single-pulse transcranial magnetic stimulation (sTMS) is an emerging neuromodulation method reported to be useful in migraine. Despite a low propensity for side effects, some concern with its use in patients with cardiac pacemakers has been expressed. CASE: We present a patient with chronic migraine with a cardiac pacemaker, who had tried unsuccessfully several migraine preventives with either poor efficacy or tolerability. With involvement of the cardiology team, we tested the effect of sTMS on her pacemaker and found it to be a safe and effective option for her. CONCLUSION: Having regard to the risk/benefit ratio of sTMS, its use in patients with disabling migraine in the presence of a cardiac pacemaker can be carefully evaluated and may represent a useful therapeutic option.

The impact of adjunctive complex fractionated atrial electrogram ablation and linear lesions on outcomes in persistent atrial fibrillation: a meta-analysis.

AIMS: In persistent atrial fibrillation (PsAF), success rates for pulmonary vein isolation (PVI) alone are limited and additional substrate modification is often performed. The two most widely used substrate-based strategies are the ablation of complex fractionated atrial electrograms (CFAE) and left atrial linear ablation (LALA) at the roof and mitral isthmus. However, it is unclear whether adjunctive CFAE ablation or LALA add significant benefit to PVI alone. We performed a meta-analysis to better gauge the benefit of adjunctive CFAE ablation and LALA in PsAF. METHODS AND RESULTS: Electronic databases were systematically searched. We included studies that examined the impact of CFAE ablation or LALA in addition to a PVI-based strategy on clinical outcomes in PsAF. We included both randomized and non-randomized studies. Totally 10 studies (n = 1821) were included: 6 evaluating CFAE ablation, 3 LALA, and 1 both approaches. In comparison with PVI alone, the addition of CFAE ablation [RR 0.86; 95% confidence intervals (CI) 0.64, 1.16; P = 0.32] or LALA (RR 0.64; 95% CI 0.37, 1.09; P = 0.10) offered no significant improvement in arrhythmia-free survival. However, adjunctive CFAE ablation was associated with significant increases (P < 0.05) and LALA non-significant increases in procedure and fluoroscopy times. CONCLUSION: In PsAF, the addition of CFAE ablation or LALA, in comparison with PVI alone, offers no significant improvement in arrhythmia-free survival. Furthermore, they are associated with increases in both procedural and fluoroscopy times. The optimal ablation strategy for PsAF is currently unclear and needs further refinement.

A multicenter study of shock pathways for subcutaneous implantable defibrillators.

INTRODUCTION: A purely subcutaneous implantable cardioverter defibrillator (ICD) requires higher energy but may be an effective alternative to transvenous ICDs to deliver lifesaving therapies. OBJECTIVE: To identify combinations of anteroposterior subcutaneous shock pathways and waveforms with defibrillation efficacy comparable to transvenous ICDs. METHODS: Defibrillation testing was performed in 141 patients temporarily implanted with an active can emulator and subcutaneous coil electrodes. The patients were subdivided into 5 groups within 2 study phases. In all groups, a posterior electrode was positioned with its tip close to the spine. In the first study phase, 2 different can locations were evaluated: (1) an inframammary pocket (IM-1-750), or (2) a conventional infraclavicular pocket (IC-1-750). In both cases, a 70 J biphasic shock was used (peak voltage 750 V; 270 µF capacitance). In the second phase, configuration IC-1-750 was enhanced by the addition of a second (parasternal) subcutaneous electrode (IC-2-750). Furthermore, the effects of a different 70 J shock waveform (1,000 V, 160 µF) were evaluated for configurations IM-1-750 and IC-2-750 (becoming IM-1-1000 and IC-2-1000). RESULTS: The proportion of patients satisfying a defibrillation safety margin test of 2 consecutive successes at ≤50 J was 74%, 11%, and 44%, respectively, for the IM-1-750, IC-1-750, and IC-2-750 configurations, and 93% and 86% for the IM-1-1000 and IC-2-1000 configurations. CONCLUSIONS: Defibrillation efficacy comparable to that of a transvenous system was achieved with an anteroposterior subcutaneous ICD configuration, with 160 µF capacitance, 1,000 V, and 70 J output. An infraclavicular pocket location becomes feasible if a parasternal subcutaneous coil is added.

An entirely subcutaneous implantable cardioverter-defibrillator.

BACKGROUND: Implantable cardioverter-defibrillators (ICDs) prevent sudden death from cardiac causes in selected patients but require the use of transvenous lead systems. To eliminate the need for venous access, we designed and tested an entirely subcutaneous ICD system. METHODS: First, we conducted two short-term clinical trials to identify a suitable device configuration and assess energy requirements. We evaluated four subcutaneous ICD configurations in 78 patients who were candidates for ICD implantation and subsequently tested the best configuration in 49 additional patients to determine the subcutaneous defibrillation threshold in comparison with that of the standard transvenous ICD. Then we evaluated the long-term use of subcutaneous ICDs in a pilot study, involving 6 patients, which was followed by a trial involving 55 patients. RESULTS: The best device configuration consisted of a parasternal electrode and a left lateral thoracic pulse generator. This configuration was as effective as a transvenous ICD for terminating induced ventricular fibrillation, albeit with a significantly higher mean (+/-SD) energy requirement (36.6+/-19.8 J vs. 11.1+/-8.5 J). Among patients who received a permanent subcutaneous ICD, ventricular fibrillation was successfully detected in 100% of 137 induced episodes. Induced ventricular fibrillation was converted twice in 58 of 59 patients (98%) with the delivery of 65-J shocks in two consecutive tests. Clinically significant adverse events included two pocket infections and four lead revisions. After a mean of 10+/-1 months, the device had successfully detected and treated all 12 episodes of spontaneous, sustained ventricular tachyarrhythmia. CONCLUSIONS: In small, nonrandomized studies, an entirely subcutaneous ICD consistently detected and converted ventricular fibrillation induced during electrophysiological testing. The device also successfully detected and treated all 12 episodes of spontaneous, sustained ventricular tachyarrhythmia. (ClinicalTrials.gov numbers, NCT00399217 and NCT00853645.)

Risk of Adverse Outcomes Associated With Cardiac Sarcoidosis Diagnostic Schemes.

BACKGROUND: Multiple cardiac sarcoidosis (CS) diagnostic schemes have been published. OBJECTIVES: This study aims to evaluate the association of different CS diagnostic schemes with adverse outcomes. The diagnostic schemes evaluated were 1993, 2006, and 2017 Japanese criteria and the 2014 Heart Rhythm Society criteria. METHODS: Data were collected from the Cardiac Sarcoidosis Consortium, an international registry of CS patients. Outcome events were any of the following: all-cause mortality, left ventricular assist device placement, heart transplantation, and appropriate implantable cardioverter-defibrillator therapy. Logistic regression analysis evaluated the association of outcomes with each CS diagnostic scheme. RESULTS: A total of 587 subjects met the following criteria: 1993 Japanese (n = 310, 52.8%), 2006 Japanese (n = 312, 53.2%), 2014 Heart Rhythm Society (n = 480, 81.8%), and 2017 Japanese (n = 112, 19.1%). Patients who met the 1993 criteria were more likely to experience an event than patients who did not (n = 109 of 310, 35.2% vs n = 59 of 277, 21.3%; OR: 2.00; 95% CI: 1.38-2.90; P < 0.001). Similarly, patients who met the 2006 criteria were more likely to have an event than patients who did not (n = 116 of 312, 37.2% vs n = 52 of 275, 18.9%; OR: 2.54; 95% CI: 1.74-3.71; P < 0.001). There was no statistically significant association between the occurrence of an event and whether a patient met the 2014 or the 2017 criteria (OR: 1.39; 95% CI: 0.85-2.27; P = 0.18 or OR: 1.51; 95% CI: 0.97-2.33; P = 0.067, respectively). CONCLUSIONS: CS patients who met the 1993 and the 2006 criteria had higher odds of adverse clinical outcomes. Future research is needed to prospectively evaluate existing diagnostic schemes and develop new risk models for this complex disease.

Power Modulation Echocardiography to Detect and Quantify Myocardial Scar.

BACKGROUND: Myocardial scar correlates with clinical outcomes. Traditionally, late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) is used to detect and quantify scar. In this prospective study using LGE CMR as reference, the authors hypothesized that nonlinear ultrasound imaging, namely, power modulation, can detect and quantify myocardial scar in selected patients with previous myocardial infarction. In addition, given the different histopathology between ischemic and nonischemic scar, a further aim was to test the diagnostic performance of this echocardiographic technique in unselected consecutive individuals with ischemic and nonischemic LGE or no LGE on CMR. METHODS: Seventy-one patients with previous myocardial infarction underwent power modulation echocardiography following CMR imaging (group A). Subsequently, 101 consecutive patients with or without LGE on CMR, including individuals with nonischemic LGE, were scanned using power modulation echocardiography (group B). RESULTS: In group A, echocardiography detected myocardial scar in all 71 patients, with good scar volume agreement with CMR (bias = -1.9 cm3; limits of agreement [LOA], -8.0 to 4.2 cm3). On a per-segment basis, sensitivity was 82%, specificity 97%, and accuracy 92%. Sensitivity was higher in the inferior and posterior segments and lower in the anterior and lateral walls. In group B, on a per-subject basis, the sensitivity of echocardiography was 62% (91% for ischemic and 30% for nonischemic LGE), with specificity and accuracy of 89% and 72%, respectively. The bias for scar volume between modalities was 5.9 cm3, with LOA of 34.6 to 22.9 cm3 (bias = -1.9 cm3 [LOA, -11.4 to 7.6 cm3] for ischemic LGE, and bias = 18.9 cm3 [LOA, -67.4 to 29.7.6 cm3] for nonischemic LGE). CONCLUSIONS: Power modulation echocardiography can detect myocardial scar in both selected and unselected individuals with previous myocardial infarction and has good agreement for scar volume quantification with CMR. In an unselected cohort with nonischemic LGE, sensitivity is low.

The Impact of Vendor-Specific Ultrasound Beam-Forming and Processing Techniques on the Visualization of In Vitro Experimental "Scar": Implications for Myocardial Scar Imaging Using Two-Dimensional and Three-Dimensional Echocardiography.

BACKGROUND: Myocardial scar appears brighter compared with normal myocardium on echocardiography because of differences in tissue characteristics. The aim of this study was to test how different ultrasound pulse characteristics affect the brightness contrast (i.e., contrast ratio [CR]) between tissues of different acoustic properties, as well as the accuracy of assessing tissue volume. METHODS: An experimental in vitro "scar" model was created using overheated and raw pieces of commercially available bovine muscle. Two-dimensional and three-dimensional ultrasound scanning of the model was performed using combinations of ultrasound pulse characteristics: ultrasound frequency, harmonics, pulse amplitude, steady pulse (SP) emission, power modulation (PM), and pulse inversion modalities. RESULTS: On both two-dimensional and three-dimensional imaging, the CR between the "scar" and its adjacent tissue was higher when PM was used. PM, as well as SP ultrasound imaging, provided good "scar" volume quantification. When tested on 10 "scars" of different size and shape, PM resulted in lower bias (-9.7 vs 54.2 mm3) and narrower limits of agreement (-168.6 to 149.2 mm3 vs -296.0 to 404.4 mm3, P = .03). The interobserver variability for "scar" volume was better with PM (intraclass correlation coefficient = 0.901 vs 0.815). Two-dimensional and three-dimensional echocardiography with PM and SP was performed on 15 individuals with myocardial scar secondary to infarction. The CR was higher on PM imaging. Using cardiac magnetic resonance as a reference, quantification of myocardial scar volume showed better agreement when PM was used (bias, -645 mm3; limits of agreement, -3,158 to 1,868 mm3) as opposed to SP (bias, -1,138 mm3; limits of agreement, -5,510 to 3,233 mm3). CONCLUSIONS: The PM modality increased the CR between tissues with different acoustic properties in an experimental in vitro "scar" model while allowing accurate quantification of "scar" volume. By applying the in vitro findings to humans, PM resulted in higher CR between scarred and healthy myocardium, providing better scar volume quantification than SP compared with cardiac magnetic resonance.

Manual vs. automatic capture management in implantable cardioverter defibrillators and cardiac resynchronization therapy defibrillators.

AIMS: The Secura ICD and Consulta CRT-D are the first defibrillators to have automatic right atrial (RA), right ventricular (RV), and left ventricular (LV) capture management (CM). Complete CM was evaluated in an implantable cardioverter defibrillator (ICD) population. METHODS AND RESULTS: Two prospective clinical studies were conducted in 28 centres in Europe and Israel. Automatic CM data were compared with manual threshold measurements, the CM applicability was determined, and adjustments to pacing outputs were analysed. In total, 160 patients [age 64.6 +/- 10.4 years, 77% male, 80 ICD and 80 cardiac resynchronization therapy defibrillator (CRT-D)] were included. The differences between automatic and manual measurements were 2.5 V) due to raised RA threshold in seven (4.4%), high RV threshold in nine (5.6%), and high LV threshold in three patients (3.8%). All high threshold detections and all automatic modulations of pacing output were adjudicated appropriate. CONCLUSION: Complete CM adjusts pacing output appropriately, permitting a reduction in office visits while it may maximize device longevity. The study was registered at ClinicalTrials.gov identifiers: NCT00526227 and NCT00526162.

The impact of catheter ablation for atrial fibrillation in heart failure.

Atrial fibrillation (AF) commonly co-exists with systolic heart failure (SHF) and its presence is associated with a worse prognosis. Despite this, a rhythm control approach using antiarrhythmic drugs (AADs) to reduce AF burden has demonstrated no prognostic benefit. Catheter ablation (AFA) is more effective than AADs at reducing AF burden. We performed a meta-analysis to evaluate the impact of AFA on outcomes in SHF. Electronic databases were systematically searched. We included only randomized controlled trials that examined the impact of AFA on clinical outcomes in patients with SHF (LVEF <50%). We included studies with any ablation strategy that incorporated pulmonary vein isolation and any control group. Seven studies (n = 858) were included with a mean follow-up of 6-38 months. In comparison to controls, AFA was associated with significant reductions in all-cause mortality (relative risk [RR] 0.52, P = 0.0009) and unplanned or heart failure hospitalization (RR 0.58, P < 0.00001). Compared to controls, AFA was also associated with significant improvements in LVEF (mean difference 6.30%, P < 0.00001), Minnesota Living with Heart Failure Questionnaire score (mean difference 9.58, P = 0.0003), 6-minute walk distance (mean difference 31.78 m, P = 0.003) and VO 2 max (mean difference 3.17, P = 0.003). However, major procedure-related complications occurred in 2.4%-15% of ablation patients. In patients with AF and SHF, catheter ablation has significant benefits. Further work is needed to establish the role of ablation in the routine treatment of SHF patients with AF.

Novel Extravascular Defibrillation Configuration With a Coil in the Substernal Space: The ASD Clinical Study.

OBJECTIVES: This study assessed the defibrillation efficacy of the substernal-lateral electrode configuration. BACKGROUND: Subcutaneous implantable cardioverter-defibrillators (ICDs) are regarded as alternatives to transvenous ICDs in certain subjects. However, substantially higher shock energy of up to 80 J may be required. Proposed is a new defibrillation method of placing the shock coil into the substernal space. METHODS: This prospective, nonrandomized, feasibility study was conducted in subjects scheduled for midline sternotomy or implant of ICD. A blunted end tunneling tool was used to insert a defibrillation lead behind the sternum using a percutaneous subxiphoid approach. A skin patch electrode was placed on the left mid-axillary line at the fourth to fifth intercostal space. After ventricular fibrillation induction, a single 35-J shock was delivered between the lead and skin patch. RESULTS: Sixteen subjects (12 males, 4 females; mean age: 61.6 ± 11.8 years) were enrolled. The mean lead placement time was 11.1 ± 6.6 min. Of the 14 subjects with successfully induced ventricular fibrillation episodes, 13 subjects (92.9%) had successful defibrillation. The 1 failure was associated with high and lateral shock coil placement. Mean ventricular fibrillation duration was 18.4 ± 5.6 s with a shock impedance of 98.1 ± 19.3 ohms. Of the 11 subjects with coil-patch electrograms, the average R-wave amplitude during sinus rhythm was 3.0 ± 1.4 mV. CONCLUSIONS: These preliminary data demonstrate that substernal defibrillation is feasible and successful defibrillation can be achieved with the shock energy available in current transvenous ICDs. This may open new alternatives to extravascular ICD therapy.

Impact of prolonged implantable cardioverter-defibrillator arrhythmia detection times on outcomes: a meta-analysis.

BACKGROUND: Programming long arrhythmia detection times can reduce the incidence of implantable cardioverter-defibrillator (ICD) shock therapy. However, potential concerns exist regarding the impact on mortality and incidence of syncope. OBJECTIVE: The purpose of this study was to perform a meta-analysis to better gauge the impact of prolonged arrhythmia detection times on the rates of ICD shock therapy and other adverse outcomes. METHODS: Electronic databases were systematically searched. We included only prospective studies that examined the impact of programming longer vs shorter ICD arrhythmia detection times on clinical outcomes. Studies that were retrospective, did not have a control group, used historical controls, or did not specifically state the programmed detection times were excluded. Summary estimates of the relative risk (RR) of death, syncope, and appropriate and inappropriate shocks were calculated using random effects models. RESULTS: Four studies enrolling 4896 patients were identified. During a mean/median follow-up of 12 to 17 months, there were 305 deaths, 106 patients experienced syncope, 264 received an appropriate shock, and 253 an inappropriate shock. In the long detection group there were significant reductions in mortality (RR 0.77, 95% confidence interval [CI] 0.62, 0.96), and inappropriate shocks (RR 0.50, 95% CI 0.39, 0.65), without significant increase in syncope (RR 1.23, 95% CI 0.84, 1.79). CONCLUSION: Programming long arrhythmia detection times is an important strategy for improving outcomes from ICD therapy. The use of long detection times can significantly decrease the burden of inappropriate shock therapy and all-cause mortality in ICD recipients, without significant increase in syncope.

"Pills and pulses": hybrid therapy for atrial fibrillation.

Nonpharmacologic techniques are being increasingly applied to the treatment of atrial fibrillation (AF). None of these techniques (other than maze surgery) begins to approach 100% efficacy for long-term elimination of arrhythmia. This review examines the evidence for "hybrid" therapy, using combinations of drug and nonpharmacologic treatments. The immediate success rate of electrical cardioversion can be increased with amiodarone or ibutilide, and a number of drugs reduce the risk of AF recurrence. Preventing or reversing electrical atrial remodeling is an attractive strategy for maintenance of sinus rhythm. However, the available evidence (relating to the use of verapamil) is limited and conflicting. Ablation of the cavotricuspid isthmus is effective when antiarrhythmic drugs given for AF give rise to typical flutter. Isthmus and other right atrial linear lesions are poor as a sole therapy for AF, but better when drugs are added. Better still is the combination of left atrial linear lesions with drugs. In patients with AF recurrence following focal ablation/pulmonary vein isolation procedures, drugs are an alternative to extensive linear ablation. Some studies indicate that pacing to prevent AF may be effective, but rarely without continued antiarrhythmic drug therapy. This may represent a specific effect or simply improved drug tolerance. Drugs also might assist pacemaker therapy by increasing the proportion of atrial arrhythmias that are highly organized and thus amenable to antitachycardia pacing. This and other forms of hybrid therapy will remain the subject of conjecture in the absence of controlled clinical trials, which are urgently needed.

Catheter cryoablation of supraventricular arrhythmias: a painless alternative to radiofrequency energy.

Cryothermy has potential advantages over RF energy for catheter ablation, including reversibility of lesion formation, catheter stability, and less procedural discomfort. Cryoablation procedures were performed in 14 patients with atrioventricular reentrant tachycardias (AVNRTs), 13 patients with accessory pathway (AP)-mediated tachycardias, and 5 patients with atrial fibrillation. The numbers of energy applications, pain scores, procedural times, and outcomes were recorded and compared with age- and sex-matched patients undergoing similar RF procedures. Cryoablation was successful in 26 of 32 patients (11/14 AVNRT, 10/13 AP, 5/5 AF) compared with 30 of 32 undergoing RF procedures, with similar numbers of energy applications and procedural times. Cryothermy was painless in all patients, and the overall procedural discomfort was significantly less than in patients treated with RF (1.3 +/- 2.2 vs 6.1 +/- 3.5). In patients with anteroseptal pathways, cryomapping successfully identified safe sites to target the delivery of energy. Cryothermy is a painless and safe alternative to RF. It may be particularly useful for catheter ablation of patients with pathways close to the atrioventricular node.

Permanent pacemakers: should straightened atrial leads be repositioned?

The aim of this study was to assess if atrial leads whose "J" configuration has straightened significantly on the postprocedural chest X ray should be repositioned. Between January 1996 and December 1997, 445 patients underwent dual chamber pacemaker implantation at the Papworth Hospital. Postprocedural chest X rays were available in 410 of these. The degree of straightening of the tip of the atrial lead was assessed from the lateral chest X ray and was graded as mild (-10 to +10 degrees from the horizontal), moderate (+10 to +30 degrees), or severe (> or = +30 degrees). Patients were followed with regard to atrial sensing and pacing characteristics, lead displacements, and lead revisions. Fifty-two (12%) patients had some degree of straightening (graded mild, moderate, severe) of the atrial lead on the postprocedure chest X ray (passive fixation in 48, active 4). Of these, 12 patients underwent next day lead repositioning, 5 of whom had abnormalities of pacing and/or sensing parameters. Seven patients therefore underwent repositioning of the atrial lead despite normal pacing parameters in view of lead straightening alone. Of the 12 patients who underwent repositioning, 3 still had lead straightening after the second procedure. The cohort for follow-up consisted of 43 patients (24 [56%] men, age 69 +/- 11 years at the time of implant) who were left with significant atrial lead straightening but adequate atrial parameters. Straightening was mild in 26 patients, moderate in 10, and severe in 7 patients. At implant the P wave amplitude was 4.8 +/- 2.4 mV. Follow-up was for 4.8 +/- 2.1 years, a total of 178 patient years. At final follow-up, the P wave amplitude was 2.7 +/- 1.3 (P < 0.05 vs implant). Censoring events occurred in 16 cases, comprising 11 deaths (none suspected to be pacemaker or lead related), 3 cases of persistent atrial fibrillation, 1 system extraction for infection, and 1 lead extraction for erosion. There were no cases of inadequate atrial lead sensing or pacing in the remaining patients. Irrespective of the degree of lead straightening on the postoperative lateral chest X ray, atrial leads should not be repositioned unless there are abnormalities of pacing or sensing parameters.