Jacob S. Koruth

Permanent Leadless Cardiac Pacing: Results of the LEADLESS Trial

Background— Conventional cardiac pacemakers are associated with several potential short- and long-term complications related to either the transvenous lead or subcutaneous pulse generator. We tested the safety and clinical performance of a novel, completely self-contained leadless cardiac pacemaker.nnMethods and Results— The primary safety end point was freedom from complications at 90 days. Secondary performance end points included implant success rate, implant time, and measures of device performance (pacing/sensing thresholds and rate-responsive performance). The mean age of the patient cohort (n=33) was 77±8 years, and 67% of the patients were male (n=22/33). The most common indication for cardiac pacing was permanent atrial fibrillation with atrioventricular block (n=22, 67%). The implant success rate was 97% (n=32). Five patients (15%) required the use of >1 leadless cardiac pacemaker during the procedure. One patient developed right ventricular perforation and cardiac tamponade during the implant procedure, and eventually died as the result of a stroke. The overall complication-free rate was 94% (31/33). After 3 months of follow-up, the measures of pacing performance (sensing, impedance, and pacing threshold) either improved or were stable within the accepted range.nnConclusions— In a prospective nonrandomized study, a completely self-contained, single-chamber leadless cardiac pacemaker has shown to be safe and feasible. The absence of a transvenous lead and subcutaneous pulse generator could represent a paradigm shift in cardiac pacing.nnClinical Trial Registration— URL: . Unique identifier: [NCT01700244][1].nn# CLINICAL PERSPECTIVE {#article-title-26}nn [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT01700244&atom=%2Fcirculationaha%2F129%2F14%2F1466.atomBackground— Conventional cardiac pacemakers are associated with several potential short- and long-term complications related to either the transvenous lead or subcutaneous pulse generator. We tested the safety and clinical performance of a novel, completely self-contained leadless cardiac pacemaker. Methods and Results— The primary safety end point was freedom from complications at 90 days. Secondary performance end points included implant success rate, implant time, and measures of device performance (pacing/sensing thresholds and rate-responsive performance). The mean age of the patient cohort (n=33) was 77±8 years, and 67% of the patients were male (n=22/33). The most common indication for cardiac pacing was permanent atrial fibrillation with atrioventricular block (n=22, 67%). The implant success rate was 97% (n=32). Five patients (15%) required the use of >1 leadless cardiac pacemaker during the procedure. One patient developed right ventricular perforation and cardiac tamponade during the implant procedure, and eventually died as the result of a stroke. The overall complication-free rate was 94% (31/33). After 3 months of follow-up, the measures of pacing performance (sensing, impedance, and pacing threshold) either improved or were stable within the accepted range. Conclusions— In a prospective nonrandomized study, a completely self-contained, single-chamber leadless cardiac pacemaker has shown to be safe and feasible. The absence of a transvenous lead and subcutaneous pulse generator could represent a paradigm shift in cardiac pacing. Clinical Trial Registration— URL: http://clinicaltrials.gov. Unique identifier: NCT01700244.

Activation and Entrainment Mapping of Hemodynamically Unstable Ventricular Tachycardia Using a Percutaneous Left Ventricular Assist Device

OBJECTIVESnOur goal was to investigate the effects of percutaneous left ventricular assist device (pLVAD) support during catheter ablation of unstable ventricular tachycardia (VT).nnnBACKGROUNDnMechanical cardiac support during ablation of unstable VT is being increasingly used, but there is little available information on the potential hemodynamic benefits.nnnMETHODSnTwenty-three consecutive procedures in 22 patients (ischemic, n = 11) with structural heart disease and hemodynamically unstable VT were performed with either pLVAD support (n = 10) or no pLVAD support (intra-aortic balloon pump counterpulsation, n = 6; no support, n = 7). Procedural monitoring included vital signs, left atrial pressure, arterial blood pressure, cerebral perfusion/oximetry, VT characteristics, and ablation outcomes.nnnRESULTSnThe pLVAD group was maintained in VT significantly longer than the non-pLVAD group (66.7 min vs. 27.5 min; p = 0.03) and required fewer early terminations of sustained VT for hemodynamic instability (1.0 vs. 4.0; p = 0.001). More patients in the pLVAD group had at least 1 VT termination during ablation than non-pLVAD patients (9 of 10 [90%] vs. 5 of 13 [38%]; p = 0.03). There were no differences between groups in duration of cerebral deoxygenation, hypotension or perioperative changes in left atrial pressure, brain natriuretic peptide levels, lactic acid, or renal function.nnnCONCLUSIONSnIn patients with scar-related VT undergoing catheter ablation, pLVAD support was able to safely maintain end-organ perfusion despite extended periods of hemodynamically unstable VT. Randomized studies are necessary to determine whether this enhanced ability to perform entrainment and activation mapping will translate into a higher rate of clinical success.

Bipolar irrigated radiofrequency ablation: A therapeutic option for refractory intramural atrial and ventricular tachycardia circuits

BACKGROUNDnIrrigated radiofrequency (RF) ablation can be insufficient to eliminate intramurally located septal atrial flutter (AFL) and ventricular tachycardia (VT) circuits. Bipolar ablation between 2 ablation catheters may be considered for such circuits.nnnOBJECTIVEnTo evaluate the utility of bipolar irrigated ablation to terminate arrhythmias resistant to unipolar ablation.nnnMETHODSnIn vitro: Bipolar and sequential unipolar RF ablation lesions were placed on porcine ventricular tissue in a saline bath to assess for lesion transmurality. Clinical: 3 patients with atypical septal flutter (AFL), 4 patients with septal VT, and 2 with left ventricle free-wall VT, all of whom failed sequential unipolar RF ablation, underwent bipolar RF ablation using irrigated catheters placed on either surface of the interatria/interventricular septum and left ventricle free-wall, respectively.nnnRESULTSnIn vitro: Bipolar RF was found to be more likely to achieve transmural lesions (82% vs 33%; P = .001) and could do so in tissues with thicknesses of up to 25 mm. Clinical: All 5 AFLs (3 patients) were successfully terminated with bipolar RF. In follow-up, AFL recurred in 2 of the 3 patients and atrial fibrillation and AFL recurred in 1 of the 3. All 3 thereafter underwent repeat procedures with successful maintenance of sinus rhythm in 2 of the 3 patients (6-month follow-up). In the VT subgroup, 5 of 6 septal VTs and 2 of 3 free-wall VTs were terminated successfully during ablation. In follow-up (12 months), 2 of the 4 patients in the septal bipolar group and 1 of the 2 patients in the free-wall group remained free of VT.nnnCONCLUSIONSnBipolar RF can be used to terminate arrhythmias in select patients with tachyarrhythmias.

Chronic performance of a leadless cardiac pacemaker: 1-year follow-up of the LEADLESS trial.

BACKGROUNDnA leadless cardiac pacemaker (LCP) system was recently introduced to overcome lead-related complications of conventional pacing systems. To date, long-term results of an LCP system are unknown.nnnOBJECTIVESnThe aim of this study was to assess the complication incidence, electrical performance, and rate response characteristics within the first year of follow-up of patients implanted with an LCP.nnnMETHODSnWe retrospectively assessed intermediate-term follow-up data for 31 of 33 patients from the LEADLESS trial cohort who had an indication for single-chamber pacing and received an LCP between December 2012 and Aprilxa02013.nnnRESULTSnThe mean age of the cohort was 76 ± 8 years, and 65% were male. Between 3 and 12 months of follow-up, there were no pacemaker-related adverse events reported. The pacing performance results at 6- and 12-month follow-up were, respectively, as follows: mean pacing threshold (at a 0.4-ms pulse width), 0.40 ± 0.26 V and 0.43 ± 0.30 V; R-wave amplitude 10.6 ± 2.6 mV and 10.3 ± 2.2 mV; and impedance 625 ± 205 Ω and 627 ± 209 Ω. At the 12-month follow-up in 61% of the patients (nxa0= 19 of 31), the rate response sensor was activated, and an adequate rate response was observed in all patients.nnnCONCLUSIONSnThe LCP demonstrates very stable performance and reassuring safety results during intermediate-term follow-up. These results support the use of the LCP as a promising alternative to conventional pacemaker systems. Continued evaluation is warranted to further characterize this system. (Evaluation of a New Cardiac Pacemaker; NCT01700244).

Acute electrical isolation is a necessary but insufficient endpoint for achieving durable PV isolation: the importance of closing the visual gap

AIMSnTemporary, ablation-mediated effects such as oedema may cause reversible pulmonary vein (PV) isolation. To investigate this, point-by-point circumferential ablation was performed to achieve acute electrical PV isolation with an incomplete circumferential ablation line. Then, the impact of this intentional visual gap (ViG) on the conduction properties of the ablation lesion set was assessed with adenosine and pacing manoeuvres.nnnMETHODS AND RESULTSnTwenty-eight patients undergoing ablation for paroxysmal (n= 20) or persistent atrial fibrillation (n= 8) were included. Pulmonary vein (PV) ablation was performed around ipsilateral vein pairs. Once acute isolation was achieved, ablation was halted and the presence and size of the ViG were calculated. The ViG electrophysiological properties were tested with pace capture along the ViG at 10 mA/2 ms, and assessment for dormant PV conduction with adenosine. Despite electrical isolation, a ViG was present in 75% (n= 42/56) of vein pairs (21 of 28 left PVs and 21 of 28 right PVs). There was no difference in the ViG size between the left and right PVs (22.1 ± 14.2 and 17.3 ± 11.3 mm, P > 0.05). Dormant PV connections were revealed by adenosine in more than a quarter (n= 12/42) of acutely isolated PV pairs, of which the majority were dependent on conduction through the ViG.nnnCONCLUSIONSnElectrical PV isolation can usually be achieved without complete circumferential ablation. However, more than a quarter of these isolated PVs exhibit dormant conduction-predominantly via the un-ablated ViGs in the ablation lesion set. These findings support the hypothesis that reversible tissue injury contributes to PV isolation that may be acute but not necessarily durable.

Multicenter study on acute and long-term safety and efficacy of percutaneous left atrial appendage closure using an epicardial suture snaring device

BACKGROUNDnPericardial suture ligation of the left atrial appendage (LAA) may be an alternative to endoluminal devices for stroke prevention in patients with atrial fibrillation, but multicenter safety and efficacy data in high-risk patients with contraindications to oral anticoagulation are lacking.nnnOBJECTIVEnThe purpose of this study was to report the outcomes of consecutive cases of pericardial suture ligation of the LAA in high-risk patients performed at 4 centers.nnnMETHODSnThe cohort included 41 consecutive patients who underwent LAA closure with the LARIAT system. Epicardial and transeptal access was obtained, and the epicardial snare was advanced over an endo-epicardial magnetic-tipped guidewire to close the LAA. Transesophageal echocardiography was used to confirm LAA exclusion.nnnRESULTSnMean age was 75 ± 10 years, mean CHADS2 score was 3.0 ± 1.3, and mean HAS-BLED score was 4.4 ± 1.4. These patients accumulated 24.6 person-years of follow-up. Acute LAA closure was achieved in 38 patients (93%). Transesophageal echocardiography or computerized tomographic angiography performed up to 3.3 ± 0.8 months after the procedure demonstrated LAA leakage in 24% of patients. One patient (2%) had a transient ischemic attack, and 8 (20%) developed pericardial effusions requiring pericardiocentesis. Four cases (9%) were complicated by perforation of the LAA, with 2 of these patients requiring open surgical correction.nnnCONCLUSIONnThis multicenter experience revealed that pericardial suture ligation with the LARIAT system is technically feasible and acutely efficacious. However, additional improvements are required to minimize the rate of pericardial complications. A randomized study is warranted to accurately define the long-term efficacy and safety profile of percutaneous epicardial suture ligation.

Percutaneous hemodynamic support with Impella 2.5 during scar-related ventricular tachycardia ablation (PERMIT 1).

Background—Percutaneous left ventricular assist devices (pLVADs) are increasingly being used to facilitate ablation of unstable ventricular tachycardia (VT), but the safety profile and hemodynamic benefits of these devices have not been described in a systematic, prospective manner. Methods and Results—Twenty patients with scar VT underwent ablation with a pLVAD. Neuromonitoring using cerebral oximetry was performed to evaluate a cerebral desaturation threshold to guide the duration of activation/entrainment mapping. The efficacy of pLVAD support was tested in a controlled manner with simulated VT. Complete procedural success was achieved in 50% (n=8) of patients, who were initially inducible for sustained VT, and partial procedural success in 37% (n=6). Using a cerebral desaturation level of 55% as a lower safety limit to guide the duration of sustained VT, 3 patients (15%) developed mild acute kidney injury (all resolved), and 1 (5%) patient developed mild cognitive dysfunction. During fast simulated VT (300 ms), cerebral desaturation to ⩽55% occurred in more than half (53%) of patients tested without pLVAD support, compared with only 5% with full pLVAD support (P=0.003). Conclusions—In a consecutive series of patients with severe left ventricular dysfunction, pLVAD-supported scar VT ablation was safe and feasible. During fast simulated VT, a miniaturized axial flow pump imparted a more favorable hemodynamic profile compared with pharmacological agents alone. Cerebral oximetry is a complimentary monitoring modality during scar VT ablation, and avoidance of cerebral desaturations below a threshold of 55% may safely guide the duration of mapping during unstable VT.

Unusual complications of percutaneous epicardial access and epicardial mapping and ablation of cardiac arrhythmias.

Background— Percutaneous epicardial access and mapping/ablation of cardiac arrhythmias are being increasingly performed. Although complications such as pericardial effusion are relatively common, other unusual complications may occur due to the complex anatomic architecture of the heart and surrounding tissues. In this report, we report a series of rare and unusual complications related to percutaneous epicardial procedures. Methods and Results— Between 2006 and 2011, 334 patients underwent attempts at percutaneous, subxiphoid access for epicardial mapping/ablation at 5 experienced centers. Seven selected complications are highlighted in this case series. Patient 1 had a 1-cm right ventricular pseudoaneurysm after several unsuccessful attempts at epicardial access. This was successfully managed conservatively. Patient 2 had intra-abdominal bleeding related to puncture of the left lobe of the liver during access that required surgical repair. Patient 3 had a subcapsular hepatic hematoma that was probably related to percutaneous access and was successfully managed conservatively. Patient 4 had severe pericardial bleeding followed by ventricular fibrillation, immediately after obtaining percutaneous epicardial access. A lacerated middle cardiac vein was repaired surgically. However, the patient ultimately died of complications. Patient 5 had a history of cardiothoracic surgery and developed a right ventricle-abdominal fistula after multiple attempts at percutaneous access. This was surgically repaired without major sequelae. Patient 6 had cardiac tamponade caused by a lacerated coronary sinus branch during epicardial catheter ablation and required surgical repair. Patient 7 had severe left coronary vasospasm and ventricular fibrillation during catheter manipulation in the pericardium. This complication was successfully managed with intracoronary nitrates. Conclusions— Though generally safe, percutaneous epicardial access and mapping/ablation can result in uncommon complications. Awareness of these rare complications may facilitate early detection and successful management.

Catheter ablation of scar-related atypical atrial flutter

AIMSnThe aim of the study was to assess the impact of isthmus location of atypical atrial flutters/atrial tachycardias (ATs) on outcomes of catheter ablation. Atrial tachycardias are clinically challenging arrhythmias that can occur in the presence of atrial scar--often due to either cardiac surgery or prior ablation for atrial fibrillation. We previously demonstrated a catheter ablation approach employing rapid multielectrode activation mapping with targeted entrainment manoeuvrs. However, the role that AT isthmus location plays in acute and long-term success of ablation remains uncertain.nnnMETHODS AND RESULTSnRetrospective multicenter analysis of 91 consecutive AT patients undergoing ablation using a systematic four-step approach: (i) high-density activation mapping; (ii) analysis of atrial activation to identify wavefronts of electrical propagation; (iii) targeted entrainment of putative channels; and (iv) irrigated radiofrequency ablation of constrained regions of the circuit. Clinical outcomes, procedural details, and clinical profiles were determined. A total of 171 ATs (1.9 ± 1.0 per patient, 26% septal ATs) were targeted for ablation. The acute success rates were 97 and 77% for patients with either non-septal ATs or septal ATs, respectively (P = 0.0023). Similarly, the long-term success rates were 82 and 67% for patients with either no septal ATs or at least one septal AT, respectively (P = 0.1057). The long-term success rates were 75, 88, and 57% for patients with ATs associated with prior catheter ablation, cardiac surgery or MAZE, and idiopathic atrial scar, respectively.nnnCONCLUSIONnCatheter ablation of AT can be successfully performed employing a strategy of combined high-density activation and entrainment mapping. Septal ATs are associated with higher rates of acute and long-term recurrences.

Adjunctive Renal Sympathetic Denervation to Modify Hypertension as Upstream Therapy in the Treatment of Atrial Fibrillation (H-FIB) Study: Clinical Background and Study Design

Hypertension is the most important risk factor directly attributable to the high prevalence of atrial fibrillation (AF), and is one of the few modifiable risk factors for AF. Activation and overactivity of the sympathetic nervous system (SNS) have been implicated in the pathogenesis of both essential hypertension and AF. Catheter‐based renal sympathetic denervation (RSDN) appears to be an effective adjunctive treatment for refractory hypertension, and may be beneficial in other conditions characterized by SNS overactivity, such as left ventricular hypertrophy and atrial arrhythmias.