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).

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.

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.

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.

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.

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.

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.

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.

Physicians' preferences and attitudes about end-of-life care in patients with an implantable cardioverter-defibrillator.

Clinical guidance is deficient regarding deactivation of implantable cardioverter-defibrillators (ICDs) in patients with terminal illnesses. We hypothesized that many physicians are apprehensive about discussing ICD deactivation with their dying patients. Thus, we conducted an anonymous survey of all the physicians in the Department of Medicine at Unity Health System in Rochester, NY. The survey collected information about the knowledge and preferences of these physicians regarding the medical, ethical, and legal issues involved in caring for patients with an ICD and terminal illness. Of the 204 surveys distributed, 87 (43%) were returned. Among the physicians who responded, 64 (74%) reported experience caring for a patient with an ICD and terminal illness. Forty physicians (46%) either thought it was illegal or were not sure if it was legal to deactivate an ICD in these circumstances. However, if reassured about the legality of discontinuing ICD therapy, 79 (91%) of these same respondents said that they would be willing to discuss voluntary ICD deactivation with their dying patients. With increased knowledge about managing the withdrawal of this potentially life-prolonging therapy, physicians are likely to become more skilled at caring for dying patients with an ICD.

Moxifloxacin-induced torsades de pointes.

Torsade de pointes (TdP) is increasingly recognized as a complication of drug therapy. The most common cause of drug-induced QT prolongation is inhibition of the rapidly activating component of the delayed potassium current (I(Kr)). Moxifloxacin, a widely used fluoroquinolone, is a weak I(Kr) inhibitor and has been associated with QT prolongation. We report a case of marked QT prolongation (618 ms) and TdP associated with moxifloxacin use. Although it is difficult to predict which patients are at risk from TdP, careful assessment of the risk/benefit ratio is important before prescribing drugs known to cause QT prolongation.

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.

Dofetilide-induced long QT and torsades de pointes.

Dofetilide, a new class III antiarrhythmic agent, has been approved as an antiarrhythmic agent for the treatment of atrial fibrillation and atrial flutter. Dofetilide selectively inhibits the rapid component of the delayed rectifier potassium current resulting in a prolongation of the effective refractory period. Like other drugs that affect potassium currents, the prolonged QT interval occurring in the patients treated with dofetilide can be complicated by torsades de pointes. We report four cases of dofetilide-induced QT prolongation and torsades de pointes. We discuss the risk factors for the development of dofetilide-induced long QT and torsades de pointes and review the current literature.

Update on implantable cardioverter defibrillator trials.

Many randomized trials of implantable cardioverter defibrillator (ICD) therapy versus medical treatment for the prevention of death in survivors of cardiac arrest or in patients at high risk of sudden cardiac death (SCD) have been reported. ICD therapy has been consistently efficacious in preventing SCD. ICD therapy has generally favorably impacted total mortality, but this has depended upon the control group's risk for arrhythmic and nonarrhythmic mortality. In these trials, predictors of sudden or total mortality better than ventricular dysfunction have not emerged. This review summarizes the randomized ICDs trials and the impact ICDs have on SCD prevention.