Abrar Shah

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.

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.

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 manufacturers performance update. Further accumulative data are needed because it remains unknown if the fracture rate will level off or continue to increase.

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.

Visualization of the esophagus during catheter ablation of atrial fibrillation.

Catheter ablation of atrial fibrillation has become an important therapeutic option for patients over the past few years. As with any evolving technique, unexpected complications can occur. Pappone et al. [1] have recently reported two cases of atrio-esophageal fistula formation as a complication of percutaneous transcatheter ablation of atrial fibrillation. Reducing the ablation temperature and power settings along the posterior left atrial wall has been suggested to reduce the risk of this complication. Identification of the esophagus’ location and avoiding lesions directly overlying the esophagus has been proposed also. Other approaches include esophageal temperature monitoring and the use of intracardiac echo to avoid esophageal injury during ablation. We have found that inserting a small enteral feeding tube (VIASYS MedSystems, Wheeling, IL) prior to the case can be helpful. We have also routinely been injecting two cubic centimeters of radiopaque contrast into the feeding tube for improved visualization. While the feeding tube does not delineate the entire esophageal structure, it does give one a general idea of the relationship between the left atrium and esophagus which varies widely among patients. In addition, the feeding tube allows one to mark esophageal anatomic points on a three dimensional map of the left atrium allowing for further characterization of the complex atrio-esophageal relationship during ablation. There are other methods that can be used for visualization of the esophagus during ablation of atrial fibrillation. The use of barium paste has been proposed and is currently being utilized in some electrophysiology laboratories. The difficulty with using barium paste is that it does not remain in the esophagus throughout the entire ablation procedure. Thus, while it is possible to obtain an initial picture of the esophagus, barium paste does not allow for a constant fluoroscopic landmark of the esophagus for the entirety of the procedure. In addition, it is necessary to give the patient the barium substance after the initial three-dimensional map of the left atrium has been constructed. This can be difficult and lead to potential complications as the patient has often already received sedation by this point in the procedure. Other investigators have suggested creating a separate esophageal map on the CARTO XP system [2]. This is accomplished by inserting a nasogastric tube into the esophagus. A 4-mm tip catheter (Navistar, Biosense Webster) is then passed down the nasogastric tube so that a pull back can be performed along the course of the esophagus near the left atrium. While this is certainly a fine method for defining the left atrial— esophageal relationship, it does add cost to the procedure because two ablation catheters are required. We have found that the fluoroscopic landmark offered by the enteral feeding tube alone allows one to adequately tag esophageal points on the left atrial map. The left atrial—esophageal anatomic relationship is likely not constant. However, we have not noted any significant movement of the enteral feeding tube as it relates to the left atrial atrium during the ablation procedure. Figure 1 shows the relationship of the enteral feeding tube and the left sided pulmonary veins

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.

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.

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.

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

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.