A Modular Communicative Leadless Pacing-Defibrillator System.

BACKGROUND: The subcutaneous implantable cardioverter-defibrillator (ICD) is associated with fewer lead-related complications than a transvenous ICD; however, the subcutaneous ICD cannot provide bradycardia and antitachycardia pacing. Whether a modular pacing-defibrillator system comprising a leadless pacemaker in wireless communication with a subcutaneous ICD to provide antitachycardia and bradycardia pacing is safe remains unknown. METHODS: We conducted a multinational, single-group study that enrolled patients at risk for sudden death from ventricular arrhythmias and followed them for 6 months after implantation of a modular pacemaker-defibrillator system. The safety end point was freedom from leadless pacemaker-related major complications, evaluated against a performance goal of 86%. The two primary performance end points were successful communication between the pacemaker and the ICD (performance goal, 88%) and a pacing threshold of up to 2.0 V at a 0.4-msec pulse width (performance goal, 80%). RESULTS: We enrolled 293 patients, 162 of whom were in the 6-month end-point cohort and 151 of whom completed the 6-month follow-up period. The mean age of the patients was 60 years, 16.7% were women, and the mean (±SD) left ventricular ejection fraction was 33.1±12.6%. The percentage of patients who were free from leadless pacemaker-related major complications was 97.5%, which exceeded the prespecified performance goal. Wireless-device communication was successful in 98.8% of communication tests, which exceeded the prespecified goal. Of 151 patients, 147 (97.4%) had pacing thresholds of 2.0 V or less, which exceeded the prespecified goal. The percentage of episodes of arrhythmia that were successfully terminated by antitachycardia pacing was 61.3%, and there were no episodes for which antitachycardia pacing was not delivered owing to communication failure. Of 162 patients, 8 died (4.9%); none of the deaths were deemed to be related to arrhythmias or the implantation procedure. CONCLUSIONS: The leadless pacemaker in wireless communication with a subcutaneous ICD exceeded performance goals for freedom from major complications related to the leadless pacemaker, for communication between the leadless pacemaker and subcutaneous ICD, and for the percentage of patients with a pacing threshold up to 2.0 V at a 0.4-msec pulse width at 6 months. (Funded by Boston Scientific; MODULAR ATP ClinicalTrials.gov NCT04798768.).

Design and rationale of the MODULAR ATP global clinical trial: A novel intercommunicative leadless pacing system and the subcutaneous implantable cardioverter-defibrillator.

Background: The subcutaneous implantable cardioverter-defibrillator (S-ICD) has demonstrated safety and efficacy for the treatment of malignant ventricular arrhythmias. However, a limitation of the S-ICD lies in the inability to either pace-terminate ventricular tachycardia or provide prolonged bradycardia pacing support. Objective: The rationale and design of a prospective, single-arm, multinational trial of an intercommunicative leadless pacing system integrated with the S-ICD will be presented. Methods: A technical description of the modular cardiac rhythm management (mCRM) system (EMPOWER leadless pacemaker and EMBLEM S-ICD) and the implantation procedure is provided. MODULAR ATP (Effectiveness of the EMPOWER™ Modular Pacing System and EMBLEM™ Subcutaneous ICD to Communicate Antitachycardia Pacing) is a multicenter, international trial enrolling up to 300 patients at risk of sudden cardiac death at up to 60 centers trial design. The safety endpoint of freedom from major complications related to the mCRM system or implantation procedure at 6 months and 2 years are significantly higher than 86% and 81%, respectively, and all-cause survival is significantly >85% at 2 years. Results: Efficacy endpoints are that at 6 months mCRM communication success is significantly higher than 88% and the percentage of subjects with low and stable thresholds is significantly higher than 80%. Substudies to evaluate rate-responsive features and performance of the pacing module are also described. Conclusion: The MODULAR ATP global clinical trial will prospectively test the safety and efficacy of the first intercommunicating leadless pacing system with the S-ICD. This trial will allow for robust validation of device-device communication, pacing performance, rate responsiveness, and system safety.

Postapproval Study of a Subcutaneous Implantable Cardioverter-Defibrillator System.

BACKGROUND: The subcutaneous implantable cardioverter-defibrillator (S-ICD) was developed to avoid complications related to transvenous implantable cardioverter-defibrillator (TV-ICD) leads. Device safety and efficacy were demonstrated previously with atypical clinical patients or limited follow-up. OBJECTIVES: The S-ICD PAS (Subcutaneous Implantable Cardioverter-Defibrillator System Post Approval Study) is a real-world, multicenter, registry of U.S. centers that was designed to assess long-term S-ICD safety and efficacy in a diverse group of patients and implantation centers. METHODS: Patients were enrolled in 86 U.S. centers with standard S-ICD indications and were observed for up to 5 years. Efficacy endpoints were first and final shock efficacy. Safety endpoints were complications directly related to the S-ICD system or implantation procedure. Endpoints were assessed using prespecified performance goals. RESULTS: A total of 1,643 patients were prospectively enrolled, with a median follow-up of 4.2 years. All prespecified safety and efficacy endpoint goals were met. Shock efficacy rates for discrete episodes of ventricular tachycardia or ventricular fibrillation were 98.4%, and they did not differ significantly across follow-up years (P = 0.68). S-ICD-related and electrode-related complication-free rates were 93.4% and 99.3%, respectively. Only 1.6% of patients had their devices replaced by a TV-ICD for a pacing need. Cumulative all-cause mortality was 21.7%. CONCLUSIONS: In the largest prospective study of the S-ICD to date, all study endpoints were met, despite a cohort with more comorbidities than in most previous trials. Complication rates were low and shock efficacy was high. These results demonstrate the 5-year S-ICD safety and efficacy for a large, diverse cohort of S-ICD recipients. (Subcutaneous Implantable Cardioverter-Defibrillator [S-ICD] System Post Approval Study [PAS]; NCT01736618).

Transcatheter Leadless Pacing in Children: A PACES Collaborative Study in the Real-World Setting.

BACKGROUND: Transcatheter Leadless Pacemakers (TLP) are a safe and effective option for adults with pacing indications. These devices may be an alternative in pediatric patients and patients with congenital heart disease for whom repeated sternotomies, thoracotomies, or transvenous systems are unfavorable. However, exemption of children from clinical trials has created uncertainty over the indications, efficacy, and safety of TLP in the pediatric population. The objectives of this study are to evaluate clinical indications, procedural characteristics, electrical performance, and outcomes of TLP implantation in children. METHODS: Retrospective data were collected from patients enrolled in the Pediatric and Congenital Electrophysiology Society TLP registry involving 15 centers. Patients ≤21 years of age who underwent Micra (Medtronic Inc, Minneapolis, MN) TLP implantation and had follow-up of ≥1 week were included in the study. RESULTS: The device was successfully implanted in 62 of 63 registry patients (98%) at a mean age of 15±4.1 years and included 20 (32%) patients with congenital heart disease. The mean body weight at TLP implantation was 55±19 kg and included 8 patients ≤8 years of age and ≤30 kg in weight. TLP was implanted by femoral (n=55, 87%) and internal jugular (n=8, 12.6%) venous approaches. During a mean follow-up period of 9.5±5.3 months, there were 10 (16%) complications including one cardiac perforation/pericardial effusion, one nonocclusive femoral venous thrombus, and one retrieval and replacement of TLP due to high thresholds. There were no deaths, TLP infections, or device embolizations. Electrical parameters, including capture thresholds, R wave sensing, and pacing impedances, remained stable. CONCLUSIONS: Initial results from the Pediatric and Congenital Electrophysiology Society TLP registry demonstrated a high level of successful Micra device implants via femoral and internal venous jugular approaches with stable electrical parameters and infrequent major complications. Long-term prospective data are needed to confirm the reproducibility of these initial findings.

Clinical In-Hospital Outcomes of Acute Myocardial Infarction in Patients With Hematological Malignancies.

Introduction The purpose of our study is to determine in-hospital outcomes of acute myocardial infarction in patients with hematological malignancies and their subtypes. Method Patient data were obtained from the nationwide inpatient sample (NIS) database between the years 2009-2014. Patients with hematological cancer subtypes and acute MI (non-ST segment elevation myocardial infarction and ST-segment elevation myocardial infarction (NSTEMI/STEMI) were identified using validated international classification of diseases (ninth revision) and clinical modification (ICD-9-CM) codes. Statistical analysis using the chi-square test was performed to determine the hospital outcomes of acute MI in patients with hematological cancers and subtypes. Results The prevalence of acute myocardial infarction was 2.4% in patients with hematological neoplasms (N=3,027,800). Amongst the subtypes of blood cancers, the highest prevalence of acute MI was seen in lymphocytic leukemia (2.9%). The mortality of MI in patients with hematological malignancies was 16.8% vs 8.8% in patients with non-hematological malignancies, in-hospital costs were $25469 ± 36763 vs. $20534 ± 24767, and length of in-hospital stay was 8.3 ± 10 vs 6.3 ± 7.8 days. Amongst the hematological cancer subtypes, the highest mortality of acute MI was found in myeloid leukemia (23%) followed by multiple myeloma (MM) (17.9%), lymphocytic leukemia (15.9%), and lymphoma (14.4%). The length of stay and hospitalization cost was highest for myeloid leukemia, followed by MM, lymphocytic leukemia, and lymphoma. Conclusion This study showed that acute MI in patients with hematological malignancies has higher in-hospital mortality, length of stay, and cost. Amongst the blood neoplasm subtypes the highest mortality, length of hospital stay, and hospitalization cost were found in myeloid leukemia.

Predictors of Early and Late Atrioventricular Block Requiring Permanent Pacemaker Implantation After Transcatheter Aortic Valve Replacement: A Single-Center Experience.

PURPOSE: Complete heart block requiring permanent pacemaker can occur early following transcatheter aortic valve replacement (TAVR) due to mechanical compression of the aortic valve annulus and associated atrio-ventricular (AV) conduction system. Data are limited regarding late PM implantation after TAVR. The purpose of this study was to determine predictors of early vs. late PM implantation post-TAVR procedure. METHODS: Baseline characteristics of patients who required PM <7 days following TAVR were compared with patients who required a PM >7 days to 1 year following TAVR using Chi-Square and multivariate regression analysis. RESULTS: There were 362 TAVR patients, of which 39 (10.4%) received a PM after TAVR. Of these 18 (4.6%) patients required PM within 7 days after TAVR, and 21 (5.8%) required PM after 7 days and up to 1 year later. Right bundle branch block (RBBB) (OR 6.721, CI 2.3-36.9, p < 0.005) was a positive predictor of early PM placement. Left bundle branch block (LBBB) (OR = 3.5, CI 1.19-10.80, p-value < 0.05) and atrial fibrillation (AF) (OR = 3.5, 1.36-9.4 p < 0.05) were predictors for late PM. Early and late PM were associated with a longer median hospital stay compared to no PM (4.9 ± 4.86 days vs. 10.1 ± 10.04 days vs. 6.10 ± 6.02 days). The incidence of heart failure was higher in the late PM group. The overall motility was not increased in early and late PM compared to no PM. CONCLUSION: Patients requiring PM implant after TAVR was 10.4%, of which 5.8% need PM >7 days post-TAVR. RBBB is a predictor for early PM. AF and LBBB were predictors for late PM.

Cardiac pseudoaneurysm as a complication of native mitral valve infective endocarditis.

BACKGROUND: The delayed development of a mitral valve annulus pseudoaneurysm is a rare and late complication of a native mitral abscess cavity. CASE SUMMARY: Currently, there are no documented cases of a pseudoaneurysm developing from an abscess cavity of the posterior annulus of the native mitral valve. We report a case of a patient who presented with worsening progressive shortness of breath that was found to be secondary to a pseudoaneurysm. This was detected by 2D echocardiogram and cardiac computed tomography angiography. DISCUSSION: In our case, the patient developed a late complication of a ventricular pseudoaneurysm originating from the mitral annular area of the abscess cavity. Per the surgical literature, one method to avoid the aforementioned complication is via cavity repair with a bovine patch.

An unusual case of orthodeoxia.

Progressive hypoxia in hospitalized patients can be due to many etiologies, especially in patients with multiple comorbidities. More unusual causes of hypoxia, such as patent foramen ovale (PFO) with a right to left shunting in the absence of elevated right atrial pressures, should be considered when workup does not reveal a specific etiology. .

Association of atrial fibrillation and various cancer subtypes.

BACKGROUND: Studies have shown that the incidence of atrial fibrillation (AF) in cancer is most likely due to the presence of inflammatory markers. The purpose of our study is to determine the association of AF with different cancer subtypes and its impact on in-hospital outcomes. METHODS: Data were obtained from the National Inpatient Sample database between 2005 and 2015. Patients with various cancers and AF were studied. ICD-9-CM codes were utilized to verify variables. Patients were divided into three age groups: Group 1 (age < 65 years), Group 2 (age 65-80 years), and Group 3 (age > 80 years). Statistical analysis was performed using Pearson chi-square and binary logistic regression analysis to determine the association of individual cancers with AF. RESULTS: The prevalence of AF was 14.6% among total study patients (n = 46 030 380). After adjusting for confounding variables through multivariate regression analysis, AF showed significant association in Group 1 with lung cancer (odds ratio, OR = 1.92), multiple myeloma (OR = 1.59), non-Hodgkin lymphoma (OR = 1.55), respiratory cancer (OR = 1.55), prostate cancer (OR = 1.20), leukemia (OR = 1.12), and Hodgkin's lymphoma (OR = 1.03). In Group 2, the association of AF with multiple myeloma (1.21), lung cancer (OR = 1.15), Hodgkin lymphoma (OR = 1.15), non-Hodgkin lymphoma (OR = 1.12), respiratory cancer (OR = 1.08), prostate cancer (OR = 1.06), leukemia (OR = 1.14), and colon cancer (OR = 1.01) were significant. In Group 3, AF showed significant association with non-Hodgkin lymphoma (OR = 1.06), prostate (OR = 1.03), leukemia (OR = 1.03), Hodgkin's lymphoma (OR = 1.02), multiple myeloma (OR = 1.01), colon cancer (OR = 1.01), and breast cancer (OR = 1.01). The highest mortality was found in lung cancer in age <80 and prostate cancer in age >80. CONCLUSION: In patients age <80 years, AF has significant association with lung cancer and multiple myeloma, whereas in patients age >80 years, it has significant association with non-Hodgkin lymphoma and prostate cancer. In patients age <80 years, increased mortality was seen in AF with lung cancer and in patients age >80 years, increased mortality was seen in those with AF and prostate cancer. TWITTER ABSTRACT: In age <80, lung cancer and multiple myeloma have a strong association with AF while thyroid and pancreatic cancers have no association with AF at any age. In age greater than 80, NHL and prostate cancer have a significant association with AF.

Association between atrial fibrillation and bundle branch block.

BACKGROUND: The association between atrial fibrillation (Afib) and sinus and AV nodal dysfunction has previously been reported. However, no data are available regarding the association between Afib and bundle branch block (BBB). METHODS: Patient data were obtained from the Nationwide Inpatient Sample (NIS) database between years 2009 and 2015. Patients with a diagnosis of Afib and BBB were identified using validated International Classification of Diseases, 9th revision, and Clinical Modification (ICD-9-CM) codes. Statistical analysis using the chi-square test and multivariate linear regression analysis were performed to determine the association between Afib and BBB. RESULTS: The total number of patients with BBB was 3,116,204 (1.5%). Patients with BBB had a mean age of 73.5 ± 13.5 years, 53.6% were males, 39.1% belonged to the age group ≥80 years, and 72.9% were Caucasians. The prevalence of Afib was higher in the BBB group, as compared to the non-BBB group (29% vs 11.8%, p value<.001). This association remained significant in multivariate regression analysis with an odds ratio of 1.25 (CI: 1.24-1.25, P < .001). Among the subtypes of BBB, Afib was comparatively more associated with RBBB (1.32, CI 1.31-1.33, p value<.0001) than LBBB (1.17, CI 1.16-1.18, p value<.0001). The mean cost was higher among Afib with BBB, compared with Afib patients without BBB ($15 795 vs $14 391, p value<.0001). There was no significant difference in the mean length of stay (5.6 vs 5.9 days, p value<.0001) or inpatient mortality (4.9% vs 4.8%). CONCLUSION: This study demonstrates that prevalence of Afib is higher in patients with BBB than without BBB. Cost are higher for Afib patients with BBB, compared to those without BBB, with no significant increase in mortality or length of stay.

Clinical outcomes of atrial fibrillation with hyperthyroidism.

BACKGROUND: Atrial fibrillation (Afib) is a common cardiac manifestation of hyperthyroidism. The data regarding outcomes of Afib with and without hyperthyroidism are lacking. HYPOTHESIS: We hypothesized that patients with Afib and hyperthyroidism have better clinical outcomes, compared with Afib patients without hyperthyroidism. METHODS: We queried the National Inpatient Sample database for years 2015-2017 using Validated ICD-10-CM codes for Afib and hyperthyroidism. Patients were separated into two groups, Afib with hyperthyroidism and without hyperthyroidism. RESULTS: The study was conducted with 68 095 278 patients. A total of 9 727 295 Afib patients were identified, 90 635 (0.9%) had hyperthyroidism. The prevalence of hyperthyroidism was higher in patients with Afib (0.9% vs 0.4%, P < .001), compared with patients without Afib. Using multivariate regression analysis adjusting for various confounding factors, the odds ratio of Afib with hyperthyroidism was 2.08 (CI 2.07-2.10; P < .0001). Afib patients with hyperthyroidism were younger (71 vs 75 years, P < .0001) and more likely to be female (64% vs 47%; P < .0001) as compared with Afib patients without hyperthyroidism. Afib patients with hyperthyroidism had lower prevalence of CAD (36% vs 44%, P < .0001), cardiomyopathy (24.1% vs 25.9%, P < .0001), valvular disease (6.9% vs 7.4%, P < .0001), hypertension (60.7% vs 64.4%, P < .0001), diabetes mellitus (29% vs 32%, P < .0001) and obstructive sleep apnea (10.5% vs 12.2%, P < .0001). Afib with hyperthyroidism had lower hospitalization cost ($14 968 ± 21 871 vs $15 955 ± 22 233, P < .0001), shorter mean length of stay (5.7 ± 6.6 vs 5.9 ± 6.6 days, P < .0001) and lower in-hospital mortality (3.3% vs 4.8%, P < .0001. The disposition to home was higher in Afib with hyperthyroidism patients (51% vs 42; P < .0001). CONCLUSION: Hyperthyroidism is associated with Afib in both univariate and multivariate analysis. Afib patients with hyperthyroidism have better clinical outcomes, compared with Afib patients without hyperthyroidism.

Shock Secondary to Aortic Root Abscess With Sterile Blood Culture.

Shock caused by an aortic root abscess is a rare phenomenon. Due to its rarity, it is commonly not diagnosed on time to have a favorable prognosis for the patient. Our case involves an 80-year-old male presenting with leukocytosis, lactic acidosis, and hypoglycemia. Initial studies were not fruitful in determining the cause of septic shock. However, an echocardiogram conducted to clarify the finding of a non-ST segment myocardial infraction led to the incidental finding of an aortic root abscess with retrograde flow, suggesting a perforated abscess without endocarditis. Though the patient expired on day seven, our case demonstrates the importance of echocardiography in diagnosing an aortic root abscess in cases with a sterile blood culture and uneventful initial lab investigations.

Burden of atrial fibrillation in patients with rheumatic diseases.

BACKGROUND: Studies have suggested that atrial fibrillation (AF) in patients with rheumatic diseases (RD) may be due to inflammation. AIM: To determine the highest association of AF among hospitalized RD patients and to determine morbidity and mortality associated with AF in hospitalized patients with RD. METHODS: The National inpatient sample database from October 2015 to December 2017 was analyzed to identify hospitalized patients with RD with and without AF. A subgroup analysis was performed comparing outcomes of AF among different RD. RESULTS: The prevalence of AF was 23.9% among all patients with RD (n = 3949203). Among the RD subgroup, the prevalence of AF was highest in polymyalgia rheumatica (33.2%), gout (30.2%), and pseudogout (27.1%). After adjusting for comorbidities, the odds of having AF were increased with gout (1.25), vasculitis (1.19), polymyalgia rheumatica (1.15), dermatopolymyositis (1.14), psoriatic arthropathy (1.12), lupus (1.09), rheumatoid arthritis (1.05) and pseudogout (1.04). In contrast, enteropathic arthropathy (0.44), scleroderma (0.96), ankylosing spondylitis (0.96), and Sjorgen's syndrome (0.94) had a decreased association of AF. The mortality, length of stay, and hospitalization costs were higher in patients with RD having AF vs without AF. Among the RD subgroup, the highest mortality was found with scleroderma (4.8%), followed by vasculitis (4%) and dermatopolymyositis (3.5%). CONCLUSION: A highest association of AF was found with gout followed by vasculitis, and polymyalgia rheumatica when compared to other RD. Mortality was two-fold higher in patients with RD with AF.

Outcomes of subcutaneous implantable cardioverter-defibrillator in dialysis patients: Results from the S-ICD post-approval study.

BACKGROUND: Patients with chronic renal disease on hemodialysis (HD) have limited vascular access and are at high risk of bacteremia. The subcutaneous implantable cardioverter-defibrillator (S-ICD) avoids vascular access, so it may be advantageous in this patient population. OBJECTIVE: The purpose of this study was to report outcomes of patients with end-stage renal disease enrolled in the multicenter S-ICD post-approval study (PAS). METHODS: S-ICD PAS patients were stratified on the basis of the presence (group 1) or absence (group 2) of HD at the time of implantation. Baseline demographic and clinical characteristics were collected. Perioperative and intermediate-term outcomes 365 days postimplantation were compared between the 2 groups. RESULTS: There were 220 patients on HD (13.4%) at the time of implantation out of 1637 patients enrolled in the S-ICD PAS. Patients on HD (group 1) were older (57.4 ± 13.2 years vs 52.5 ± 15.2 years; P < .0001), more likely to be of African descent (48.6% vs 25.1%; P < .0001), and had lower ejection fraction (28.6% ± 11.3% vs 32.6% ± 14.9%; P < .0001) as compared with patients not on HD (group 2). Group 1 had more comorbidities and mortality was higher (17.4% vs 3.7%) than did group 2. The rate of complications calculated using the Kaplan-Meier estimate did not differ between the 2 groups (overall P = .9169), with a 1-year rate of 7.9% and 7.7% for groups 1 and 2, respectively. The rate of appropriate shocks was significantly higher in group 1 (Kaplan-Meier analysis, P = .0003), as was inappropriate shocks (P = .0137). CONCLUSION: S-ICD is associated with similar adverse event rates but a higher risk of inappropriate and appropriate therapy in dialysis patients than in nondialysis patients.

Outcomes of Standard Permanent Active Fixation Leads for Temporary Pacing.

OBJECTIVES: This study investigated the performance of Temporary Pacing via an Externalized Active-Fixation (TPEAF) lead. BACKGROUND: The incidence of cardiac implantable electronic device infections is increasing, which necessitates the need for transvenous lead extraction (TLE). Pacemaker-dependent patients require temporary pacing during the guideline-recommended waiting period before reimplantation. Data regarding safety and efficacy of TPEAF leads are very limited. METHODS: We evaluated patients implanted with TPEAF leads post-TLE at our center between April 2004 and December 2017. RESULTS: TPEAF leads were placed in 158 patients. The mean age was 74 ± 11 years. The median duration of the temporary lead was 6 days (range 1 to 29). There were 4 procedural complications (2.5% incidence): 1 patient had cardiac arrest from hyperkalemia, 2 developed cardiac tamponade, and 1 had profuse bleeding from the entry point of the leads. There were 13 complications post-implantation (8.2% incidence): 8 lead dislodgments, 1 elevated pacing threshold, 2 vegetations on the temporary lead, 1 pneumothorax, and 1 loss of capture due to the generator "safety switch." All dislodgements occurred within 24 h, except 1 on day 3. Sixteen patients died during the hospital stay: 10 due to septic shock, 2 due to hyperkalemic cardiac arrest, 3 due to ventricular tachycardia, and 1 due to a massive cerebrovascular accident. CONCLUSIONS: The use of TPEAF leads is safe and efficacious in pacemaker-dependent patients post-TLE. Dislodgement can occur within the first 24 h. The presence of persistent fever and positive blood cultures should raise concern for vegetation on the temporary lead.

Prophylactic use of the implantable cardioverter-defibrillator and its effect on the long-term survival, cardiovascular and sudden cardiac death in nonischemic cardiomyopathy patients-a systematic review and meta-analysis.

Implantable cardioverter-defibrillator (ICD) has shown to reduce sudden cardiac death and overall mortality in patients with dilated cardiomyopathy. The recently published DANISH trial has shown conflicting outcomes on the long-term survival in patients with prophylactic implantation of ICD in Non-Ischemic Cardiomyopathy (NICM). Two independent reviewers searched MEDLINE, PUBMED, Ovid, CINAHL, clinicaltrials.gov , and Cochrane Registry for randomized control trials (RCT's) comparing ICD to medical treatment (MT). Six RCT's enrolling 3389 patients (ICD = 1554 and MT = 1835) were included for final analysis. The primary outcomes were mortality comparing ICD to MT, 231 vs 337 (OR = 0.74, CI = 0.62-0.90, p = 0.002, and I2 = 0%) favoring ICD. On comparing to amiodarone only, there were 47 deaths in the ICD arm vs 71 deaths in amiodarone arm, (OR = 0.66, CI = 0.44-0.98, p = 0.04, I2 0%), to placebo and usual care only (excluding amiodarone); there were 225 deaths in ICD patients compared to 266 in the placebo and usual care arm, (OR = 0.73, CI = 0.59-0.92, p = 0.007, I2 = 15%). The results of our analysis from these six RCTs clearly support the ongoing benefit of prophylactic ICD implantation and support current recommendations for ICD implantation in NICM patients. More RCT's at a larger scale are needed to further elucidate benefits of both ICD and CRT-D in this post PARADIGM era where MT is at a pinnacle in reducing morbidity and mortality in heart failure patients.

Feasibility of extravascular pacing with a novel substernal electrode configuration: The Substernal Pacing Acute Clinical Evaluation study.

BACKGROUND: Subcutaneous implantable cardioverter-defibrillators provide an alternative to transvenous defibrillation but require higher shock outputs and offer no antitachycardia pacing. The Substernal Pacing Acute Clinical Evaluation (SPACE) study evaluated the feasibility of pacing from an extravascular substernal location. OBJECTIVES: The primary purpose of the SPACE study was to characterize pacing from the substernal space. Secondary objectives included evaluating extracardiac stimulation and recording electrograms. METHODS: The SPACE study prospectively evaluated the feasibility of pacing with a commercially available electrophysiology catheter acutely implanted in the substernal space via minimally invasive subxiphoid access. Pacing data were collected in ≥7 vectors using constant current stimulation up to 20 mA and pulse width up to 10 ms. RESULTS: Catheter placement was successful in all 26 patients who underwent the procedure, with a mean placement time of 11.7 ± 10.1 minutes. Eighteen patients (69%) had successful ventricular capture in ≥1 tested vector. The mean pacing threshold at a pulse width of 10 ms was 7.3 ± 4.2 mA across all vectors (5.8 ± 4.4 V). Failed capture was generally associated with suboptimal catheter placement or presumed air ingression. A low level of extracardiac stimulation was observed in 1 patient. The mean R-wave amplitude ranged from 2.98 to 4.11 mV in the unipolar configuration and from 0.83 to 3.95 mV in the bipolar configuration. CONCLUSION: The data from the SPACE study demonstrate that pacing is feasible from the extravascular substernal location. A substernal electrode configuration has the potential to provide pacing in a future extravascular device without need for intracardiac hardware placement.

Subcutaneous implantable cardioverter-defibrillator Post-Approval Study: Clinical characteristics and perioperative results.

BACKGROUND: The subcutaneous implantable cardioverter-defibrillator (S-ICD) was developed to reduce short- and long-term complications associated with transvenous ICD leads. Early multicenter studies included younger patients with less left ventricular systolic dysfunction and fewer comorbidities than cohorts with traditional ICD. OBJECTIVE: The purpose of this study was to characterize patient selection and the acute performance of the S-ICD in a contemporary real-world setting. METHODS: The S-ICD Post-Approval Study is a prospective registry involving 86 US centers. Patients were enrolled if they met criteria for S-ICD implantation, passed an electrocardiogram screening test, and had a life expectancy of >1 year. Analyses of descriptive statistics, Kaplan-Meier time to event, and multivariate logistic regression were performed. RESULTS: The study includes 1637 patients who underwent S-ICD implantation. The cohort included 68.6% (1123/1637) male patients, and 13.4% (220/1636) were receiving dialysis for end-stage renal disease. The mean age was 52 ± 15 years, with a mean left ventricular ejection fraction of 32.0% ± 14.6%. Electrocardiogram screening was successful for at least 1, 2, or 3 vectors in 100%, 93.8%, and 51.4% of patients, respectively. Medical imaging (65.1%, 1065/1636) and general anesthesia (64.1%, 1048/16) were used in a majority of patients, and 52.2% (855/1637) were implanted with the 2-incision technique. Induced ventricular tachycardia/ventricular tachycardia was successfully converted in 98.7% (1394/1412) of patients. The 30-day complication-free rate was 96.2%. Predictors of complications included diabetes, younger age, and higher body mass index. CONCLUSION: Contemporary US patients with S-ICD have more comorbidities than do previous cohorts with S-ICD, but they are younger with more end-stage renal disease than do patients with transvenous ICD. Implantation success is high, and short-term complication rates are acceptable.