CIED malfunction in patients receiving radiation is a rare event that could be detected by remote monitoring.

INTRODUCTION: An increasing number of patients with cardiac devices require radiation therapy for treatment of a variety of cancers. This study aimed to identify the incidence and predictors of cardiac implantable electronic devices (CIED) malfunction in a real-world population that has received radiation therapy. METHODS: This retrospective cohort study included 109 adult patients who received radiation therapy at the University of Rochester Medical Center, Radiation Oncology Department, between 2000 and 2015. Sixty patients had pacemakers and 49 had automatic implantable cardioverter defibrillators. Subjects received either high energy (16 MV) and/or low energy (6 MV) photon beams with or without electron beams (6-16 MeV). We included interrogations done from first day of radiation and up to 3 months' postradiation therapy. Outcomes analyzed were device-related malfunctions and device-related clinical events. Fisher's exact, Wilcoxon, and Kruskall-Wallis tests were used for bivariate analysis. Logistic regression with robust adjustment was used for multivariate analysis. RESULTS: We identified six device-related malfunctions. All events were minor and included partial settings reset leading to loss of historical data, pacing thresholds changes, lead impedance changes, and LV output increase. Two patients had device-related clinical events, including dyspnea and diaphragmatic-stimulation. In bivariate analysis, CIED malfunction was associated with CIED duration in situ. In multivariate analysis, there was no significant statistical association between adverse events and beam energy type, CIED location, or dose of radiation delivered to the target. CONCLUSIONS: CIED malfunctions are uncommon in real-world patients and associated with minor clinical events. In our cohort, remote CIED monitoring would have identified all events.

Sex-Related Differences in Ventricular Tachyarrhythmia Events in Patients With Implantable Cardioverter-Defibrillator and Prior Ventricular Tachyarrhythmias.

BACKGROUND: Data on the risk of ventricular tachycardia (VT), ventricular fibrillation (VF), and death by sex in patients with prior VT/VF are limited. OBJECTIVES: This study aimed to assess sex-related differences in implantable cardioverter-defibrillator (ICD)-treated VT/VF events and death in patients implanted for secondary prevention or primary prevention ICD indications who experienced VT/VF before enrollment in the RAID (Ranolazine Implantable Cardioverter-Defibrillator) trial. METHODS: Sex-related differences in the first and recurrent VT/VF requiring antitachycardia pacing or ICD shock and death were evaluated in 714 patients. RESULTS: There were 124 women (17%) and 590 men observed during a mean follow-up of 26.81 ± 14.52 months. Compared to men, women were at a significantly lower risk of VT/VF/death (HR: 0.67; P = 0.029), VT/VF (HR: 0.68; P = 0.049), VT/VF treated with antitachycardia pacing (HR: 0.59; P = 0.019), and VT/VF treated with ICD shock (HR: 0.54; P = 0.035). The risk of recurrent VT/VF was also significantly lower in women (HR: 0.35; P < 0.001). HR for death was similar to the other endpoints (HR: 0.61; P = 0.162). In comparison to men, women presented with faster VT rates (196 ± 32 beats/min vs 177 ± 30 beats/min, respectively; P = 0.002), and faster shock-requiring VT/VF rates (258 ± 56 beats/min vs 227 ± 57 beats/min, respectively; P = 0.30). There was a significant interaction for the risk of VT/VF by race (P = 0.013) with White women having significantly lower risk than White men (HR: 0.36; P < 0.001), whereas Black women had a similar risk to Black men (HR: 1.06; P = 0.851). CONCLUSIONS: Women with a history of prior VT/VF experienced a lower risk recurrent VT/VF requiring ICD therapy when compared to men. Black Women had a risk similar to men, whereas the lower risk for VT/VF in women was observed primarily in White women. (Ranolazine Implantable Cardioverter-Defibrillator Trial; NCT01215253).

End-of-life care in patients with implantable cardioverter defibrillators: a MADIT-II substudy.

BACKGROUND: Implantable cardioverter defibrillator (ICD)-delivered shocks can cause substantial distress, warranting consideration of ICD deactivation at end of life. This study was designed to describe the patterns of end-of-life management in patients with ICDs. METHODS: There was a retrospective chart review of 98 patients who died in the ICD arm of multicenter automated defibrillator implantation trial II (MADIT II). The pattern of ICD management and the frequency of ICD shocks delivered before death were reviewed. RESULTS: We identified three groups: Group 1 consisting of individuals who underwent ICD, deactivation, 15 (15%); Group 2 patients without ICD deactivation who were in hospice or with "do not resuscitate" (DNR) orders, 36 (37%); and Group 3 patients without ICD deactivation who were not in hospice care and did not have DNR orders, 47 (48%). Out of 15 deactivations, 11 (73%) occurred in the week before death. None of the patients in Group 1 received an ICD shock in the 24-hour period before death. However, one (3%) patient from Group 2 and nine (19%) patients from Group 3 had shocks during the 24 hours before death (P = 0.03). In the last week before death, three (20%), two (6%), and six (13%) patients received ICD shocks in the three groups, respectively (P = 0.28). CONCLUSIONS: In patients with terminal conditions who are at risk for imminent death, active management of the patient's ICD, including timely discussions regarding ICD deactivation, may reduce the risk of ICD shocks during the end of life.

Safety and Efficacy of Direct Oral Anticoagulants Versus Warfarin Following WATCHMAN in High-Risk Patients.

Background: In the pivotal WATCHMAN trials, warfarin was used exclusively for postprocedural anticoagulation following left atrial appendage closure. We sought to investigate the safety and efficacy of direct oral anticoagulants (DOACs) in high-risk patients with atrial fibrillation who underwent left atrial appendage closure with WATCHMAN. Methods: This was a retrospective study of 318 patients who underwent the WATCHMAN procedure in a tertiary referral center (June 2016-September 2020). We compared the outcomes of patients who were discharged on DOACs versus warfarin after the WATCHMAN procedure. The primary outcome was the composite of any bleeding, thromboembolism, or cardiovascular death through 7 â€‹days and 45 â€‹days after the procedure. Results: The final analysis included 301 patients, of whom 82.4% (248/301) were discharged on DOACs and 17.6% (53/301) were discharged on warfarin. The mean CHA2DS2-VASc and HAS-BLED scores were 4.9 â€‹± â€‹1.6 and 2.9 â€‹± â€‹0.9, respectively. The primary composite outcome was similar between the DOAC and warfarin groups through 7 â€‹days (3.2% vs 5.6%; adjusted odds ratio [OR], 0.65; 95% confidence interval [CI], 0.13-3.17; P â€‹= â€‹.59) and 45 days after procedure (10.1% vs 11.3%; adjusted OR, 1.18; 95% CI, 0.41-3.45; P â€‹= â€‹.76). Major bleeding (5.2% vs 9.5%; P â€‹= â€‹.34) and all-cause readmission (12.5% vs 16.9%; P â€‹= â€‹.85) at 45 â€‹days were comparable between the DOAC and warfarin groups. The overall incidence of device-related thrombus and significant peri-device flow at 45 â€‹days were low (<0.5%). Conclusions: In high-risk patients with atrial fibrillation, the primary composite outcome of any bleeding, thromboembolism, or cardiovascular death through 7 â€‹days and 45 â€‹days following WATCHMAN implantation was similar in patients receiving DOACs versus warfarin.

Safety and Feasibility of Same-Day Discharge After Left Atrial Appendage Closure With the WATCHMAN Device.

BACKGROUND: As the use of left atrial appendage closure (LAAC) becomes more widespread, improvements in resource utilization and cost-effectiveness are necessary. Currently, there are limited data on same-day discharge (SDD) after LAAC. We aimed to evaluate the safety and feasibility of SDD versus non-SDD in patients with nonvalvular atrial fibrillation who underwent LAAC. METHODS: We retrospectively studied 211 patients who underwent the WATCHMAN procedure in a tertiary hospital (June 2016 to June 2019). The primary safety outcome was the composite of stroke, systemic embolism, major bleeding requiring transfusion, vascular complications requiring endovascular intervention, or death through 7 days (periprocedural) and 45 days post-procedure. The secondary outcomes were the individual components of the primary outcome and all-cause readmission. We compared the clinical outcomes of patients who had SDD and non-SDD post-procedure. RESULTS: Patients with procedure-related complications on the day of LAAC and patients who were admitted for acute clinical events before LAAC were excluded. One hundred ninety patients were included in the final analysis. Seventy-two of 190 (38%) patients had SDD, and 118 of 190 (62%) had non-SDD. There were no statistically significant differences in the primary safety outcome through 7 days (1.4% versus 5.9%; P=0.26) and 45 days post-procedure (2.8% versus 9.3%; P=0.14) between the two groups. The secondary outcomes were similar in both groups. No patients had device-related thrombus on transesophageal echocardiography at 45 days. Only 1 patient from the non-SDD group had clinically significant peri-device flow (>5 mm) at 45 days. CONCLUSIONS: In a selected cohort of patients who underwent successful elective LAAC with WATCHMAN without same-day procedure-related complications, the primary safety outcome and secondary outcomes through 7 and 45 days post-procedure were similar in the SDD and non-SDD groups. Our findings are hypothesis generating and warrant further investigation in prospective trials.

Absence of left bundle branch block and blood urea nitrogen predict improvement in left ventricular ejection fraction in patients with cardiomyopathy and wearable cardioverter defibrillators.

OBJECTIVE: To identify predictors of left ventricular ejection fraction (LVEF) improvement in patients with newly detected cardiomyopathy using wearable cardioverter defibrillators (WCDs). BACKGROUND: WCDs are useful in preventing sudden cardiac death in patients with reduced LVEF <35% while awaiting implantable cardioverter defibrillator (ICD) placement. In many patients, LVEF improves and an ICD is not indicated. METHODS: Patients who received WCDs from November 2013 to November 2015 were identified and followed over a period of 2 years. Clinical variables were examined. The primary outcome was improvement in LVEF ≥35%. Predictors of outcome were determined using a multivariate logistic regression model. RESULTS: A total of 179 patients were followed. Median age was 65 (interquartile range [IQR]: 56, 73) years, 69.3% were men. Median baseline LVEF was 20% (IQR: 15, 30). LVEF improved ≥35% in 47.5% patients, with patients being younger (62 vs 68.5 years, P = .006), having lower blood urea nitrogen (BUN) (19 vs 24 mg/dL, P = .002), fewer left bundle branch block (LBBB 9.5% vs 25.8%, P = .004), shorter QRS duration (98 vs 112 ms, P < .001), and higher use of angiotensin converting enzyme inhibitors (ACEI)/angiotensin receptor blockers (ARB) (92.9% vs 74.4%, P = .001) compared to those without LVEF improvement. Absence of LBBB (odds ratio [OR] 0.28, 95% confidence interval [CI] 0.11-0.70), lower BUN (OR 0.13, 95% CI 0.02-0.76), and ACEI/ARB use (OR 3.53, 95% CI 1.28-9.69) were identified as independent predictors. Ventricular tachycardia/ventricular fibrillation was observed in three patients, all of whom received successful WCD shocks. CONCLUSION: Absence of LBBB, lower BUN, and ACEI/ARB use predicts LVEF improvement. WCDs help treat arrhythmic events.

Direct His bundle pacing post AVN ablation.

Atrioventricular nodal (AVN) ablation with concomitant pacemaker implantation is one of the strategies that reduce symptoms in patients with atrial fibrillation (AF). However, the long-term adverse effects of right ventricular (RV) apical pacing have led to the search for alternating sites of pacing. Biventricular pacing produces a significant improvement in functional capacity over RV pacing in patients undergoing AVN ablation. Another alternative site for pacing is direct His bundle to reduce the adverse outcome of RV pacing. Here, we present a case of direct His bundle pacing using steerable lead delivery system in a patient with symptomatic paroxysmal AF with concurrent AVN ablation.

Defibrillation coil reversal: a rare cause of abnormal noise and inappropriate shocks.

We report a rare case of inadvertent reversal of the defibrillator shock coils during generator change which then resulted in both intermittent, recurrent "noise" on both the rate sensing and the shock electrogram leads and multiple inappropriate shocks.

Impact of Left Atrial Appendage Exclusion on Cardiovascular Outcomes in Patients With Atrial Fibrillation Undergoing Coronary Artery Bypass Grafting (From the National Inpatient Sample Database).

Left atrial appendage (LAA) exclusion is performed by some surgeons in patients with atrial fibrillation (AF) who undergo coronary artery bypass grafting (CABG). However, the available evidence regarding the efficacy and safety of this procedure remains mixed. We queried the Nationwide Inpatient Survey Database for the 10-year period from 2004 to 2013. Using International Classification of Diseases, Ninth Edition, Clinical Modification diagnosis codes, we identified patients who had a diagnosis of AF and underwent a primary procedure of CABG with or without LAA exclusion. We then performed a 1:5 matching based on the CHA2DS2VASc score between patients who got LAA exclusion and those who did not (control group). The primary outcome was the incidence of in-hospital cerebrovascular events, whereas the secondary outcomes included in-hospital bleeding events, pericardial effusion, cardiac tamponade, postoperative shock, and mortality. Our analysis included a total of 15,114 patients. Patients who underwent LAA exclusion had significantly less incidence of cerebrovascular events (2.0% vs 3.1%, p = 0.002). However, LAA exclusion group had higher incidences of bleeding events (36.4% vs 21.3%, p <0.001), pericardial effusion (2.7% vs 1.2%, p <0.001), cardiac tamponade (0.6% vs 0.2%, p <0.001), and postoperative shock (1.2% vs 0.4%, p <0.001). LAA exclusion was associated with higher in-hospital mortality (1.6% vs 0.3%, p <0.001). Multivariate regression analysis showed that LAA exclusion was significantly associated with lower cerebrovascular accident events and higher in-hospital mortality. In conclusion, LAA exclusion in patients with AF undergoing CABG might be associated with a lower incidence of in-hospital cerebrovascular events. This benefit is offset by a higher incidence of higher bleeding events, pericardial effusion, cardiac tamponade, postoperative shock, and in-hospital mortality.

Prospective serial evaluation of myocardial perfusion and lipids during the first six months of pravastatin therapy: coronary artery disease regression single photon emission computed tomography monitoring trial.

OBJECTIVES: This study was designed to assess prospectively changes in serum lipid profile and myocardial perfusion with serial radionuclide single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) during the first six months of pravastatin therapy. BACKGROUND: Morbid coronary events occur despite statin therapy and lipid-lowering in patients with coronary artery disease (CAD). A reliable strategy to identify responders with effective treatment from nonresponders on statin therapy before clinical events is needed. METHODS: Rest and stress SPECT MPI and lipids were assessed serially in 25 patients (36% women) with CAD and dyslipidemia during the first six months of pravastatin therapy. RESULTS: Total cholesterol, low-density lipoprotein cholesterol, and triglycerides declined (26%, 32%, and 30%, respectively) by six weeks and remained reduced at six months. Mean stress perfusion defect (summed stress score [SSS]) was severe (13.3 +/- 6.0) at baseline, showed no change at six weeks, and improved significantly at six months (10.3 +/- 7.3, p < 0.01). The six-month study SSS improved in 11 (48%) patients, was unchanged in 10 (43%) patients, and worsened in 2 (9%) patients. Changes in lipid levels did not reliably predict changes in myocardial perfusion at six weeks or six months in this small pilot study. CONCLUSIONS: Serial SPECT MPI demonstrated improved stress myocardial perfusion in 48% of patients treated for six months with pravastatin. Time course of improved myocardial perfusion during pravastatin therapy is delayed compared to lipids. Direction and magnitude of changes in the myocardial perfusion vary and do not correlate closely with improvements in lipids.

Predictors of mortality in patients hospitalized for congestive heart failure with left ventricular ejection fraction ≥ 40.

BACKGROUND: There are limited data regarding the predictors of mortality in patients with acute congestive heart failure (CHF) and left ventricular ejection fraction (LVEF) ≥ 40%. METHODS: We evaluated clinical characteristics, mortality and prognostic factors in a sample of consecutive patients hospitalized for CHF with LVEF ≥ 40%. Multivariable Cox regression models were developed to predict mortality using baseline clinical characteristics and echocardiographic variables. RESULTS: The study population consisted of 191 patients, mean age 70 ± 14.6 years (60% female) with average follow-up of 4.0 ± 2.8 years. Cumulative 5-year mortality was 58% in the entire population and it was 59% in men and 57% in women (p = 0.411). In multivariable analyses, predictors of mortality were the following: blood urea nitrogen (BUN) > 25 mg/dL (HR = 1.77; p = 0.002); absence of hypertension (HR = 1.58; p = 0.032), left ventricular end diastolic dimension (LVEDD) ≤ 4.1 cm (HR = 1.73; p = 0.011) and LVEF ≤ 45% (HR = 1.69; p = 0.027). CONCLUSIONS: Patients hospitalized for heart failure with LVEF ≥ 40% have very high mortality. Absence of hypertension, elevated BUN and lower LVEF ≤ 45% indicate increased risk of short- and long-term mortality. Lower LVEDD is an independent predictor of mortality in heart failure patients with LVEF ≥ 40%.

Comparison of low versus high (>40 mm Hg) pulse pressure to predict the benefit of cardiac resynchronization therapy for heart failure (from the Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy Trial).

Low pulse pressure (PP) is associated with poor outcome in hospitalized patients with systolic heart failure (HF). However, the relation between PP and response to cardiac resynchronization therapy with defibrillator (CRT-D) is unknown. We aimed to evaluate the relation between preimplantation PP and echocardiographic response to CRT-D and subsequent clinical outcome after 1 year. The relation between preimplantation PP and echocardiographic response to CRT-D (defined as >15% reduction in left ventricular (LV) end-systolic volume at 1 year) was evaluated in 754 patients with CRT-D with left bundle branch block enrolled in Multicenter Automatic Defibrillator Cardioverter Defibrillator Implantation Trial-Cardiac Resynchronization Therapy. The association between PP at 1 year and the risk for subsequent HF or death was evaluated using multivariate Cox model. Patients with high versus low PP (>40 vs ≤40 mm Hg [lower quartile]) had a significantly greater reduction in LV end-systolic volume, LV end-diastolic volume, and LV dyssynchrony (p<0.01 for all comparisons). In multivariate analysis, the presence of high PP was associated with a 3.5-fold (p<0.001) increase in the likelihood of a positive echocardiographic response to CRT-D. Patients with high PP (>40 mm Hg, >lower quartile) 1 year after CRT-D implantation experienced a 50% reduction in the risk of subsequent HF or death (p=0.001) and 63% reduction in death only (p=0.001), compared with patients with low PP. In conclusion, high baseline PP is an independent predictor of echocardiographic response to CRT-D, and high PP after device implantation is associated with improved subsequent clinical outcome.

Underutilization of Implantable Cardioverter Defibrillator in Primary Prevention of Sudden Cardiac Arrest.

BACKGROUND: The aim of this study was to evaluate the overall use of implantable cardioverter defibrillators (ICD) for primary prevention of sudden cardiac arrest (SCA), among eligible patients from an outpatient cardiology clinic and to determine what factors might contribute to underutilization of ICDs. METHODS: This report was a retrospective chart review of patients with ischemic or non-ischemic cardiomyopathy and left ventricular ejection fraction ≤ 35% from an outpatient cardiology practice from January 2005 to May 2008. These patients met the eligibility criteria for ICD implantation for primary prevention of SCA. A detailed review of medical records captured distribution of ICD implantation including future plans for ICD implant, patient preference against ICD use, presence of severe co-morbidities, and any other documented reasons/contraindications regarding ICD implantation. RESULTS: Of the 275 patients who were eligible for ICD for primary prevention of SCA, 119 (43%) had an ICD implantation. ICDs were used in 84 (48%) eligible men and 35 (35%) eligible women (P 0.02). Among 156 (57%) patients who did not receive ICD, 79 (28%) had severe co-morbidities precluding them from having ICD. Twenty-six patients (10%) refused to have ICD implanted. The remaining 51 (19%) patient charts did not include any documentation regarding ICD use (future plan or contraindication). CONCLUSIONS: ICDs are underutilized for primary prevention of SCA, with rates of use being lowest among eligible women. This underutilization exists even after accounting for patient preferences and presence of severe co-morbid conditions that might make an otherwise eligible patient not a suitable candidate for ICD implantation.

Corrected QT interval as a predictor of mortality in elderly patients with syncope.

BACKGROUND: Prolonged corrected QT interval (QTc) holds independent prognostic importance in predicting mortality in patients with coronary artery disease, diabetes mellitus and congestive heart failure. However, its association with all cause or cardiac mortality in the general population remains unclear. We evaluated the relationship between prolonged QTc and total mortality among patients with syncope. METHODS: This was a retrospective study of 348 patients presenting to the emergency department with syncope of any etiology over a period of one year. All patients with atrial fibrillation, left bundle branch block and cardiac devices (pacemaker/defibrillator) were excluded. Prolonged QTc interval was defined as QTc interval ≥ 440 ms. The primary end point for this study was total mortality in patients presenting with syncope. RESULTS: There were 58 (16%) deaths in this population during a mean follow-up of 30 months. Patients with prolonged QTc interval had significantly higher mortality when compared to those with normal QTc interval (22% vs 11%; p = 0.004). This significance was not retained after adjustment for covariates in the Cox regression model, where we found that age ≥ 65 years (hazard ratio [HR] 7.9; 95% confidence interval [CI] 1.9-32.9; p = 0.004) and QTc interval ≥ 500 ms (HR 3.5; 95% CI 1.56-8.12; p = 0.002) were predictors of increased mortality among patients with syncope. CONCLUSIONS: In elderly patients presenting to the emergency department with syncope, QTc interval ≥ 500 ms helps identify patients at higher risk of adverse outcomes.

Physicians' knowledge and attitudes regarding implantable cardioverter-defibrillators.

BACKGROUND: Information is limited regarding the knowledge and attitudes of physicians typically involved in the referral of patients for implantable cardioverter-defibrillator (ICD) implantation. METHODS: We conducted a survey of primary care physicians and cardiologists at the University of Rochester Medical Center and the Unity Health System Rochester, NY from December 2008 to February 2009. The survey collected information regarding physicians' knowledge of and attitudes towards ICD therapy. RESULTS: Of the 332 surveys distributed, 110 (33%) were returned. Over-all 94 (87%) physicians reported referring patients for ICD implantation. Eighteen (17%) physicians reported unawareness of guidelines for ICD use. Sixty-four (59%) physicians recommended ICD in patients with ischemic cardiomyopathy and left ventricular ejection fraction (LVEF) < or = 35%. Sixty-five (62%) physicians use < or = 35% as the LVEF criterion for ICD referral in patients with non-ischemic cardiomyopathy. Cardiologists were more familiar than primary care physicians with LVEF criteria for implantation of ICD in patients with ischemic and non-ischemic cardiomyopathy (p value 0.005 and 0.002, respectively). Twenty-nine (27%) participants were unsure regarding the benefits of ICDs in eligible women and blacks. Eighty two (76%) physicians believed that an ICD could benefit patients > or = 70 years old, whereas only 53 (49%) indicated that an ICD would benefit patients > or = 80. CONCLUSIONS: A lack of familiarity with current clinical guidelines regarding ICD implantation exists. Primary care physicians are less aware of clinical guidelines than are cardiologists. This finding highlights the need to improve the dissemination of guidelines to primary care physicians in an effort to improve ICD utilization.

Meta-analysis of the effect of radiofrequency catheter ablation on left atrial size, volumes and function in patients with atrial fibrillation.

The effects of radiofrequency catheter ablation (RFCA) on left atrial (LA) size, volumes, and function in patients with atrial fibrillation (AF) are not well understood. The aim of this study was to systematically review the effects of RFCA on LA size, volumes, and function in patients with AF. Medline, the Web of Science, the Cochrane Central Register of Controlled Trials, and the reference lists of retrieved reports were searched for relevant studies through April 2009. Studies conducted in patients with AF were included if their primary outcomes were changes in LA size or volumes and/or function before and after RFCA. Weighted mean differences for changes in LA diameter, LA maximum volume, LA minimum volume, LA ejection fraction, and LA active emptying fraction were estimated using fixed- and random-effects meta-analyses. Seventeen relevant studies (enrolling 869 patients) among 192 identified studies were included in the final analysis. Compared to preablation values, there were significant decreases in LA diameter and LA volumes at postablation follow-up. However, compared to preablation values, there were no significant differences in LA ejection fraction and LA active emptying fraction at postablation follow-up. Decreases in LA diameter and LA volumes remained significant in those without AF recurrence but not in those with AF recurrence. LA ejection fraction and LA active emptying fraction did not decrease in patients without AF recurrence, whereas they decreased in patients with AF recurrence. In conclusion, successful RFCA in patients with AF significantly decreases LA size and volumes and does not seem to adversely affect LA function.

Time-dependent risk of Fidelis lead failure.

The Medtronic Sprint Fidelis leads (models 6930, 6931, 6948, 6949) are 6.6-F bipolar high-voltage implantable cardioverter-defibrillator electrodes that were first introduced in September 2004. In October 2007, Fidelis leads were removed from the market. We sought to determine the time-dependent hazard of the Fidelis failure rate to date. A retrospective chart review was conducted in all patients who underwent implantation of a Sprint Fidelis lead (426 leads) at our center. We primarily implanted models 6931 and 6949. With 1,056 years of combined follow-up (average 2.3 +/- 1), 38 of 426 (8.92%) Sprint Fidelis leads failed (3.6%/year). The hazard of fracture increased exponentially over time by a power of 2.13 (95% confidence interval [CI] 1.98 to 2.27, p <0.001) and the 3-year survival was 90.8% (95% CI 87.4 to 94.3). If a Fidelis lead was functioning normally at 1 year, the chance it would survive another year was 97.4% (95% CI 95.7 to 99.1); if functioning at 2 years, the chance of surviving another year was 94.7% (95% CI 91.8 to 97.7); and if functioning at 3 years, the chance of surviving 1 more year was 86.7% (95% CI 78.8 to 95.5). Other commonly used implantable cardioverter-defibrillator leads showed no evidence of increased failure rates. In conclusion, to date, the hazard of Fidelis lead fracture is increasing exponentially with time and, based on our data, occurring at a higher rate than the latest manufacturer's performance update. Further accumulative data are needed because it remains unknown if the fracture rate will level off or continue to increase.

Permanent pacemaker implantation via left superior vena cava without communication with the coronary sinus.

The persistence of the left superior vena cava is a rare venous anomaly and usually does not produce hemodynamic disturbances. Left sided cardiac device implantation has increased the awareness of this rare anomaly. In most cases, left superior vena cava connects to the right heart via coronary sinus. We describe a rare case of successful permanent pacemaker implantation via left superior vena cava-accessory hemiazygos-hemiazygos-inferior vena caval communication.

Effect of biventricular pacing during a ventricular sensed event.

Loss of biventricular (BiV) pacing occurs during ventricular sensed events such as frequent ventricular ectopy, nonsustained ventricular tachycardia, and intrinsic atrioventricular nodal conduction, such as in atrial fibrillation. Ventricular sense response (VSR) pacing, a novel cardiac resynchronization therapy pacing strategy, maintains BiV pacing during these sensed ventricular events. Patients who underwent echocardiographic optimization after BiV pacemaker implantation were enrolled, and aortic velocity-time integrals (VTIs) were recorded and compared during intrinsic conduction without pacing, optimized BiV pacing, and intrinsic conduction with VSR pacing alone. Thirty-two patients were enrolled (mean age 68 +/- 11 years, 78% men), with a mean baseline QRS duration of 164 +/- 24 ms and a mean left ventricular ejection fraction of 23 +/- 10%. The mean aortic VTI during intrinsic conduction with VSR pacing was 16.5 +/- 3.6 cm, compared with 15.3 +/- 3.4 cm during intrinsic conduction without pacing (p <0.001). The mean aortic VTI with optimized BiV pacing was 17.3 +/- 3.6 cm, significantly better (p <0.001) compared with intrinsic conduction without pacing. Improvements in aortic VTI were higher with optimized BiV pacing compared with VSR pacing alone (p = 0.02). In the subgroup of patients with left bundle branch block-type activation, the hemodynamic improvements realized with VSR pacing were similar to optimized BiV pacing. Mean aortic VTI improvements with VSR were similar in patients with ischemic and nonischemic cardiomyopathy. In conclusion, a cardiac resynchronization therapy algorithm that maintains BiV pacing during a ventricular sensed event appears to have an aortic VTI response that is significantly better compared with intrinsic conduction without pacing.