Improvement of left ventricular function with surgical revascularization in patients eligible for implantable cardioverter-defibrillator.

INTRODUCTION: Left ventricular ejection fraction (EF) ≤ 35% is the cornerstone criterion for implantable cardioverter-defibrillator (ICD) eligibility. Improvement in EF may occur in ICD-eligible patients after coronary artery bypass graft surgery (CABG). However, the incidence, predictors, and outcomes of this process are unclear. METHODS AND RESULTS: We studied 427 patients with EF ≤ 35% who underwent CABG in the Surgical Treatment for Ischemic Heart Failure (STICH) trial and had a systematic pre- and postoperative (4 months) EF assessment using the identical cardiac imaging modality. All imaging studies were interpreted at a core laboratory. Improvement in EF was defined as postoperative EF > 35% and >5% absolute improvement from baseline. Of the 427 patients (mean age 61.8 ± 9.5 and 50 women), 125 (29.2%) had EF improvement. Their mean EF increased from 26.8% (±5.8%) to 43.3% (±6.5%) (p < .0001). EF improvement occurred in only 20% of patients with a preoperative EF < 25%. The odds of EF improvement were 1.96 times higher (95% confidence interval [CI]: 0.91-4.23, p = .09) in patients with myocardial viability. In adjusted analyses, EF improvement was associated with a significantly lower risk of all-cause mortality (hazard ratio [HR]: 0.58, 95% CI: 0.35-0.96; p = .03) and heart failure mortality (HR: 0.31, 95% CI: 0.11-0.87; p = .027). CONCLUSION: Nearly 1/3rd of ICD-eligible patients undergoing CABG had significant improvement in EF, obviating the need for primary prevention ICD implantation. These results provide patients and clinicians data on the likelihood of ICD eligibility after CABG and support the practice of reassessment of EF after revascularization.

Long-Term Outcomes After Transcatheter and Surgical Aortic Valve Replacement in Patients With Cirrhosis: A Guide for the Hepatologist.

BACKGROUND AND AIMS: Hepatologists often determine whether transcatheter aortic valve replacement (TAVR) or surgical aortic valve replacement (SAVR) is preferred for patients with cirrhosis and severe aortic stenosis. The goal of this cohort study is to compare outcomes following TAVR and SAVR in patients with cirrhosis to inform the preferred intervention. APPROACH AND RESULTS: Prospectively collected data on 105 consecutive patients with cirrhosis and aortic stenosis who underwent TAVR (n = 55) or SAVR (n = 50) between 2008 and 2016 were reviewed retrospectively. Two control groups were included: 2,680 patients without cirrhosis undergoing TAVR and SAVR and 17 patients with cirrhosis who received medical therapy alone. Among the 105 patients with cirrhosis, the median Society of Thoracic Surgeons score was 3.8% (1.5, 6.9), and the median Model for End-Stage Liver Disease (MELD) score was 11.6 (9.4, 14.0). The TAVR group had similar in-hospital (1.8% vs. 2.0%) and 30-day mortality (3.6% vs. 4.2%) as the SAVR group. During the median follow-up of 3.8 years (95% confidence interval, 3.0-6.9), there were 63 (60%) deaths. MELD score (adjusted hazard ratio, 1.13; 95% confidence interval, 1.05-1.21; P = 0.002) was an independent predictor of long-term survival. In the subgroup of patients with MELD score <12, the TAVR group had reduced survival compared with the SAVR group (median survival of 2.8 vs. 4.4 years; P = 0.047). However, in those with MELD score ≥12, survival after TAVR, SAVR, and medical therapy was similar (1.3 vs. 2.1 vs. 1.6 years, respectively; P = 0.53). CONCLUSION: In select patients with cirrhosis, both TAVR and SAVR have acceptable and comparable short-term outcomes. MELD score, but not Society of Thoracic Surgeons score, independently predicts long-term survival after TAVR and SAVR. For patients with MELD score <12, SAVR is a preferred procedure; however, neither procedure appears superior to medical therapy in patients with MELD score ≥12.

Catheter ablation of premature ventricular contractions originating from periprosthetic aortic valve regions.

BACKGROUND: Little is known about the ablation outcomes of premature ventricular contractions (PVCs) that originate from the periprosthetic aortic valve (PPAV) regions of patients with aortic valve replacement (AVR). METHODS AND RESULTS: Our study had 11 patients who underwent catheter ablation for PVCs arising from the PPAV regions (bioprosthetic aortic valve, n = 5; mechanical aortic valve, n = 6). The PVC characteristics, procedure characteristics, and efficacy of ablation were compared with the control group (n = 33). At baseline, the PPAV group had a lower left ventricular ejection fraction (mean [SD], 41% [12%] vs. 51% [8%]; p = .002). The rate of acute ablation success was 90.9% in the PPAV group. Ablation sites were identified above the left coronary cusp (LCC) and right coronary cusp commissure (LRCC) in one PVC, below the prosthetic valve in eight PVCs (four below LCC and four below LRCC), and within the distal coronary sinus in two PVCs. The mean procedure time, fluoroscopy time, and radiation in the PPAV group were all significantly greater than those in the control group (all p < .05). However, the number of radiofrequency ablation energy deliveries was not different. The PPAV group had a long-term success rate compared with the control group (72.7% vs. 87.9%, p = .48) and an increase of left ventricular ejection fraction from 43% to 49% after successful PVC ablation at follow-up (p < .001). Echocardiography showed no significant change in valve regurgitation after ablation. No new atrioventricular block occurred. CONCLUSION: PVCs arising from PPAV regions can be successfully ablated in patients with prior AVR, without damaging the prosthetic aortic valve and atrioventricular conduction.

Incremental benefit of a novel signal recording system during mapping and ablation.

AIMS: Current electrophysiology signal recording and mapping systems have limited dynamic range (DR) and bandwidth, which causes loss of valuable information during acquisition of cardiac signals. We evaluated a novel advanced signal processing platform with the objective to obtain and assess additional information of clinical importance. METHODS AND RESULTS: Over 10 canines, we compared intracardiac recordings within all cardiac chambers, in various rhythms, in pacing and during radiofrequency (RF) ablation across two platforms; a conventional system and the PURE EP™ [(PEP); Bio Sig Technologies, Inc., Los Angeles, CA, USA]. Recording cardiac signals with varying amplitudes were consistently and reproducibly observed, without loss of detail or introduction of artefact. Further the amplitude of current of injury (COI) on the unipolar signals correlated with the instantaneous contact force (CF) recorded on the sensing catheter in all the animals (r2 = 0.94 in ventricle). The maximum change in the unipolar COI correlated with the change in local electrogram amplitude during non-irrigated RF ablation (r2 = 0.61 in atrium). Reduction in artefact attributable to pacing (20 sites) and noise during ablation (48 sites) was present on the PEP system. Within the PEP system, simultaneous display of identical signals, filtered differently, aided the visualization of discrete conduction tissue signals. CONCLUSION: Compared to current system, the PEP system provided incremental information including identifying conduction tissue signals, estimates of CF and a surrogate for lesion formation. This novel signal processing platform with increased DR and minimal front-end filtering may be useful in clinical practice.

Electroporation of epicardial autonomic ganglia: Safety and efficacy in medium-term canine models.

BACKGROUND: Endocardial radiofrequency ablation of epicardial ganglionic plexus (GP) for atrial fibrillation (AF) is complicated by myocardial damage. OBJECTIVES: We hypothesized that an epicardial approach with a novel nitinol catheter system capable of causing irreversible electroporation (IRE) with direct current (DC) could selectively and permanently destroy GP without collateral myocardial injury. METHODS: Acute studies and medium-term terminal studies (mean survival, 1137 days) were performed with seven dogs. In the acute studies, DC was used to target epicardial GP within the transverse sinus, oblique sinus, vein of Marshall, and right periaortic space. Successful electroporation was defined as the presence of ablative lesions in the GP without collateral myocardial damage. A four-point integer system was used to classify histologic changes in tissue harvested from the ablation sites. Atrial effective refractory period (AERP) was measured during the acute and medium-term studies. RESULTS: For six dogs in the medium-term studies, the postablation period was uneventful without complications. Lesions were successfully created at 20 of 21 sites (95.2%) with more than minimal myocardial damage in one dog. An increase in AERP occurred in both atria during the acute studies but was maintained only in the right atrium at medium-term follow-up (5032 milliseconds). No dog had damage to the esophagus, adjacent great arteries, or pulmonary veins. CONCLUSIONS: This proof-of-concept study suggests that safe, effective, and selective epicardial ablation of GP can be performed with DC by IRE with minimal collateral myocardial damage.

Comparing the incidence of ventricular arrhythmias during epicardial ablation in swine versus canine models.

BACKGROUND: Choosing the appropriate animal model for development of novel technologies requires an understanding of anatomy and physiology of these different models. There are little data about the characteristics of different animal models for the study of technologies used for epicardial ablation. We aimed to compare the incidence of ventricular arrhythmias during epicardial radiofrequency ablation between swine and canine models using novel epicardial ablation catheters. METHODS: We conducted a retrospective study using data obtained from epicardial ablation experiments performed on swine (Sus Scrofa) and canine (Canis familiaris) models. We compared the incidence of ventricular arrhythmias during ablation between swine and canine using multivariate regression analysis. Six swine and six canine animals underwent successful epicardial radiofrequency ablation. A total of 103 ablation applications were recorded. RESULTS: Ventricular arrhythmias requiring cardioversion occurred in 13.11% of radiofrequency ablation applications in swine and 9.75% in canine (relative risk: 117.6%, 95% confidence interval [CI]: 83.97-164.69, animal-based odds ratio [OR]: .55, 95% CI: .23-61.33; P = .184). When adjusting for application position, duration of ablation and power, the odds of developing potentially lethal ventricular arrhythmia in swine increased significantly compared to canine (OR: 3.60, 95% CI: 1.35-9.55; P = .010). CONCLUSIONS: The swine myocardium is more susceptible to developing ventricular arrhythmias compared to canine model during epicardial ablation. This issue should be carefully considered in future studies.

Percutaneous epicardial pacing using a novel transverse sinus device.

BACKGROUND: Transvenous lead implantation has multiple drawbacks and complications that can be overcome by epicardial lead placement. We aimed to design percutaneously implanted epicardial leads that are anchored through the transverse sinus (TS). METHODS AND RESULTS: We designed a novel multielectrode pacing device with four bipole electrode pairs. The device is advanced through the TS, with both ends externalized out of the pericardium. We tested the prototype in one proof-of-concept and 5 additional acute canine experiments. The TS device recorded ventricular and atrial electrograms. The median amplitude of near-field ventricular electrograms was 3.3 mA (IQR 2.0-4.3) and of near-field atrial electrograms was 2.1 mA (IQR 1.3-2.2). The median ventricular threshold (N  =  30) was 1.1 mA (IQR 0.7-3.1) at a median pulse width of 0.5 ms (IQR 0.5-0.5). The median atrial threshold (N  =  10) was 2.4 mA (IQR 1.1-7.8) at a median pulse width of 0.5 ms (IQR 0.5-0.9). Right and left ventricular and atrial pacing morphologies were noted while pacing electrodes adjacent to these chambers. Simultaneous left (LV) and right ventricular (RV) pacing showed reduction in QRS duration from 116 ms (RV) and 105 ms (LV) to 91 ms. On necropsy, the device was located in the TS in all animals. There were TS abrasions in one animal, and no other acute complications. CONCLUSIONS: This study highlights a novel approach to epicardial pacing harnessing the unique anatomy of the transverse sinus as an anchoring point. Placement of this novel transverse sinus device was safe and feasible, with acceptable atrial and ventricular thresholds.

Beating Heart Validation of Safety and Efficacy of a Percutaneous Pericardiotomy Tool.

INTRODUCTION: Epicardial procedures frequently require pericardial manipulation. We aimed to develop a nonsurgical percutaneous pericardial modification tool that may (1) facilitate epicardial-based procedures by enabling adhesiolysis or (2) attenuate the myocardial constraining effect of the pericardium. METHODS: Three novel devices were developed to enable pericardiotomy, all of which can be deployed in over-the-wire fashion following percutaneous epicardial access. The grasper permits us to seize the pericardial membrane providing leverage for incision. The scissors enables anterograde cutting maneuvers. The reverse-slitter allows retrograde incisions; in addition, this device has a deflectable tip that increases the potential cutting area. We optimized these tools for safety by including electrodes to test for phrenic nerve stimulation as well as myocardial stimulation to determine directionality of the cutting devices. The base of the scissors and reverse-slitter are also blunt ensuring that the cutting element is always away from the myocardium. RESULTS: Following 5 nonbeating heart bench test experiments for prototype development, 11 animal (9 canine, 2 swine) studies were performed. Of these 2 were proof-of-concept open chest studies; the remaining 9 were entirely closed-chest, percutaneous procedures allowing for remodification of the prototypes. The tools successfully permitted incision of the pericardium in all studies. Hemodynamic measurements were assessed postincision and showed no compromise of systolic function. No coronary artery or phrenic nerve damage was seen in any study. CONCLUSION: Percutaneous pericardiotomy is feasible and appears to be safe. It may provide leverage in epicardial-based procedures and offer treatment options in disease processes characterized by pericardial restraint.

Blood Pressure Responses to Endovascular Stimulation: A Potential Therapy for Autonomic Disorders With Vasodilatation.

BACKGROUND: We have previously shown that sympathetic ganglia stimulation via the renal vein rapidly increases blood pressure. This study further investigated the optimal target sites and effective energy levels for stimulation of the renal vasculatures and nearby sympathetic ganglia for rapid increase in blood pressure. METHODS: The pre-study protocol for endovascular stimulations included 2 minutes of stimulation (1-150 V and 10 pulses per second) and at least 2 minutes of rest during poststimulation. If blood pressure and/or heart rate were changed during the stimulation, time to return to baseline was allowed prior to the next stimulation. RESULTS: In 11 acute canine studies, we performed 85 renal artery, 30 renal vein, and 8 hepatic vasculature stimulations. The mean arterial pressure (MAP) rapidly increased during stimulation of renal artery (95 ± 18 mmHg vs. 103 ± 15 mmHg; P < 0.0001), renal vein (90 ± 16 mmHg vs. 102 ± 20 mmHg; P = 0.001), and hepatic vasculatures (74 ± 8 mmHg vs. 82 ± 11 mmHg; P = 0.04). Predictors of a significant increase in MAP were energy >10 V focused on the left renal artery, bilateral renal arteries, and bilateral renal veins (especially the mid segment). Overall, heart rate was unchanged, but muscle fasciculation was observed in 22.0% with an output >10 V (range 15-150 V). Analysis after excluding the stimulations that resulted in fasciculation yielded similar results to the main findings. CONCLUSIONS: Stimulation of intra-abdominal vasculatures promptly increased the MAP and thus may be a potential treatment option for hypotension in autonomic disorders. Predictors of optimal stimulation include energy delivery and the site of stimulation (for the renal vasculatures), which informs the design of subsequent research.

The effect of mitral valve surgery on ventricular arrhythmia in patients with bileaflet mitral valve prolapse.

BACKGROUND: Bileaflet mitral valve prolapse (biMVP) is associated with frequent ventricular ectopy (VE) and malignant ventricular arrhythmia. We examined the effect of mitral valve (MV) surgery on VE burden in biMVP patients. METHODS: We included 32 consecutive patients undergoing MV surgery for mitral regurgitation secondary to biMVP between 1993 and 2012 at Mayo Clinic who had available pre- and post-operative Holter monitoring data. Characteristics of patients with a significant reduction in postoperative VE (group A, defined as >10% reduction in VE burden compared to baseline) were compared with the rest of study patients (group B). RESULTS: In the overall cohort, VE burden was unchanged after the surgery (41 interquartile range [16, 196] pre-surgery vs. 40 interquartile range [5186] beats/hour [bph] post-surgery; P = 0.34). However, in 17 patients (53.1%), VE burden decreased by at least 10% after the surgery. These patients (group A) were younger than the group B (59 ± 15 vs. 68 ± 7 years; P = 0.04). Other characteristics including pre- and postoperative left ventricular function and size were similar in both groups. Age <60 years was associated with a reduction in postoperative VE (odds ratio 5.8; 95% confidence interval, 1.1-44.7; P = 0.03). Furthermore, there was a graded relationship between age and odds of VE reduction with surgery (odds ratio 1.9; 95% confidence interval 1.04-4.3 per 10-year; P = 0.04). CONCLUSIONS: MV surgery does not uniformly reduce VE burden in patients with biMVP. However, those patients who do have a reduction in VE burden are younger, perhaps suggesting that early surgical intervention could modify the underlying electrophysiologic substrate.

HAS-BLED and CHA2DS2-VASc scores as predictors of bleeding and thrombotic risk after continuous-flow ventricular assist device implantation.

BACKGROUND: HAS-BLED and CHA2DS2-VASc scores predict bleeding in patients on anticoagulation and thromboembolic (TE) risk in patients with atrial fibrillation, respectively. We hypothesized that these scores would be predictive of bleeding and TE complications following continuous-flow ventricular assist device (CF-VAD) implantation. METHODS AND RESULTS: Baseline HAS-BLED and CHA2DS2-VASc scores were retrospectively determined for 173 consecutive patients who underwent HeartMate II CF-VAD implantation at a single center from 2005 to 2011. Forty-three patients had bleeding (24.9%) and 22 had TE (12.7%) events over a 290 patient-year follow-up period. The mean ± SD HAS-BLED scores were 2.7 ± 1.0 and 1.9 ± 1.1 (P < .0001) in patients with and without bleeding, respectively. The CHA2DS2-VASc scores were 3.6 ± 1.4 and 2.9 ± 1.5 (P = .03) in patients with and without TE events, respectively. A HAS-BLED score of ≥ 3 was associated with a significantly higher risk of bleeding events compared with a score of <3 (42% vs 15%, respectively; hazard ratio [HR] 3.40, 95% confidence interval [CI] 1.82-6.32; P < .001). A CHA2DS2-VASc score of ≥ 3 was associated with a higher risk of TE events compared with a score of <3 (18% vs 4%, respectively; HR 4.02, 95% CI 1.19-13.6; P = .025). CONCLUSIONS: Baseline HAS-BLED and CHA2DS2-VASc scores of ≥ 3 conferred significantly higher risks of bleeding and TE, respectively, following HeartMate II implantation.

What to do about primary-prevention implantable cardiac defibrillators in patients with improved ejection fraction.

Approximately 20-40% of heart failure patients with reduced ejection fraction (EF) demonstrate substantial improvements in their EF during follow-up. A subset of these patients who had originally received implantable cardioverter defibrillators (ICD) for the primary prevention of sudden cardiac death (i.e., patients with EF < 35%) pose a challenge to cardiologists when they present with improvements in EF to above 35% at the time of their battery depletion. Little is known about the risk of sudden cardiac death in these patients. Is the risk high enough to warrant the replacement of the ICD generator? In the following article, we review the available data on the risk of sudden cardiac death in these patients, and aim to assist the clinician and the patient in making informed decisions about whether the ICD therapy should be continued.

Incidence of appropriate shock in implantable cardioverter-defibrillator patients with improved ejection fraction.

BACKGROUND: Heart failure with recovered ejection fraction (EF) is a recently described clinical entity. There is insufficient information on the management of implantable-cardioverter defibrillator (ICD) patients with improved EF at generator replacement. METHODS AND RESULTS: We examined the incidence of appropriate shocks in 91 consecutive patients with ICDs for primary prevention of sudden death who underwent generator replacement. Improved EF was defined as both EF >35% at generator replacement and increase in EF by ≥10% since original implantation. Patients were 70 ± 11 years old, and 76% had ischemic cardiomyopathy. At generator replacement, 25 patients (27%) had improved EF (0.49 ± 0.08 vs 0.31 ± 0.07 at baseline; P < .0001). Over 6.2 ± 2.2 years of follow-up after original implantation, 9 patients (36%) with improved EF versus 19 (29%) with unchanged EF had appropriate ICD shocks (P = .51). Incidence of appropriate ICD shocks was similar between the two groups before (P = .90) and after (P = .97) generator replacement. Of the 9 improved EF patients with appropriate shock, 4 had shocks before generator replacement, 2 had shocks before and after generator replacement, and 3 patients, who never had shocks before, had their first shock after generator replacement. CONCLUSIONS: Some ICD patients whose EF improves to >35% at generator replacement remain at risk for appropriate ICD shocks.

Stellate ganglia stimulation counteracts vagal stimulation by significantly increasing heart rate and blood pressure.

BACKGROUND: Vasovagal syncope (VVS) is the leading cause of syncope. The most frequent mechanism is that of a cardioinhibitory response, vasodepressor response, or mixture of both. Neural stimulation that negates or overcomes the effects of vagal tone may be used as a treatment strategy for VVS. METHODS: Six male canines were studied. Stimulation (10-Hz, 2 ms pulse duration, 2 min duration) of the cervical vagus (CV), thoracic vagus (TV), and stellate ganglia (SG) was performed using needle electrodes at 3 V, 5 V, and 10 V output. SG stimulation at an output of 10 V overlaying TV stimulation at the same output was performed. Heart rate (HR), blood pressure (BP), and cardiac output (CO) were measured before, during, and after stimulation. RESULTS: Right cervical vagal stimulation was associated with significant hemodynamic changes. HR, SBP, and DBP were reduced (107 ± 16 vs. 78 ± 15 bpm [P < 0.0001], 116 ± 24 vs. 107 ± 28 mmHg [P = 0.002] and 71 ± 18 vs. 58 ± 20 mmHg [P < 0.0001]), respectively, while left cervical vagal stimulation had minimal changes. CV stimulation was associated with greater hemodynamic changes than TV stimulation. Left and right SG stimulation significantly increased systolic blood pressure (SBP), diastolic blood pressure (DBP), and HR at 5 V and 10 V, which could be observed within 30 s after stimulation. An output-dependent increase in hemodynamic parameters was seen with both left and right SG stimulation. No difference between left and right SG stimulation was seen. SG stimulation overlay significantly increased HR, BP, and CO from baseline vagal stimulation bilaterally. CONCLUSIONS: Stellate ganglia stimulation leads to increased HR and BP despite significant vagal stimulation. This may be exploited therapeutically in the management of vasovagal syncope.

Predictive value of interatrial block on electrocardiogram among obese patients undergoing atrial fibrillation ablation.

BACKGROUND: Determine a predictive value of interatrial block (IAB) on atrial fibrillation (AF) ablation outcomes in obese patients. METHODS: Medical records were retrospectively reviewed for 205 consecutive patients with body mass indices (BMI) ≥ 30 kg/m2 who underwent initial AF ablation. Evidence of partial IAB defined as P-wave duration (PWD) ≥ 120 ms and advanced IAB with PWD ≥ 120 ms and biphasic or negative P-wave in inferior leads was examined from sinus electrocardiograms (ECGs) within 1-year pre-ablation. The primary outcome was recurrent atrial arrhythmia after 3-month blanking period post-ablation. RESULTS: The mean BMI was 36.9 ± 5.7 kg/m2. Partial IAB and advanced IAB were observed in 155 (75.61%) and 42 (20.49%) patients, respectively. During the median follow-up of 1.35 (interquartile range 0.74, 2.74) years, 115 (56.1%) patients had recurrent atrial arrhythmias. In multivariable analysis adjusting for age, gender, persistent AF, use of antiarrhythmic drugs (AADs), left atrial volume index (LAVI), partial IAB, and advanced IAB were independent predictors of recurrent arrhythmia with hazard ratio (HR) of 2.80 (95% confidence interval [CI] 1.47-6.05; p = 0.001) and HR 1.79 (95% CI 1.11-2.82; p = 0.017), respectively. The results were similar in a subgroup analysis of patients who had no severe left atrial enlargement and a subgroup analysis of patients who were not on AADs. CONCLUSIONS: IAB is highly prevalent in patients with obesity and AF. Partial IAB, defined as PWD ≥ 120 ms, and advanced IAB with evidence of biphasic P-wave in inferior leads were independently associated with increased risk of recurrent arrhythmia after AF ablation. Its predictive value is independent of other traditional risk factors, LAVI, or use of AADs.