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Dofetilide is an antiarrhythmic agent and primarily eliminated renally. Initial dosing is determined by creatinine clearance, calculated by total body weight in the Cockcroft-Gault equation. To date, there is no evidence comparing the dosing of dofetilide in obese versus nonobese patients. We conducted a retrospective review of 217 adults admitted for dofetilide loading to evaluate the tolerability of dofetilide in obese versus nonobese patients. The rate of dose adjustments, including dose reductions and discontinuations, was compared between obese versus nonobese patients in unadjusted and adjusted analyses. Electrocardiograms were collected throughout the loading period, and calculation of QT intervals was performed. Obese patients did not have a significantly higher frequency of dose adjustments compared with nonobese patients (51.5% vs. 44.8%, P = 0.33). Using total body weight to determine starting doses was associated with great odds of dose adjustments compared with ideal body weight (OR 3.69, P = 0.002) and adjusted body weight (OR 4.46, P = 0.02). Men required significantly fewer dose adjustments compared with women on multivariate analysis (OR 0.53, P = 0.03). Obesity is not associated with an increase in the rate of dose adjustments. Total body weight should be used with caution to calculate initial doses of dofetilide in women because it may lead to a higher rate of dose adjustments compared with ideal body weight. Additional studies are needed to confirm the optimal method for selecting starting doses of dofetilide in women, particularly those with a body mass index of ≥30.

Background There are limited and conflicting data regarding the prevalence of tricuspid regurgitation (TR) after cardiac device implantation (implantable cardioverter defibrillator [ICD]; permanent pacemaker [PPM]). Objective The goal of this study was to assess the prevalence of TR after cardiac device implantation and determine its clinical significance. Methods A total of 1,596 patients, who had cardiac devices implanted between 2005 and 2011 at the Cleveland Clinic and had at least one preimplantation echocardiogram and at least one postimplantation echocardiogram were included in this study. A total of 3,566 postimplantation echocardiograms were available for the 1,596 patients (median follow-up 10 months). The primary end point was postimplantation TR and the secondary end point was all-cause mortality after implantation. We have used a cumulative logistic nonlinear mixed-effects model to assess the temporal trend of TR prevalence and a parametric multiphase hazard model to assess survival. Results Of the 1,596 patients (mean age: 60 ± 10 years, 61% of patients were men), 985 (62%) had ICDs (including 334 patients with cardiac resynchronization therapy defibrillator) and 611 (38%) had PPMs. The prevalence of grade 3 or 4+ TR increased from 27% to 31% by 1 month and to 35% at 4 years. Accordingly, prevalence of grade 0/1+ TR decreased from 46% preimplantation to 37% at 1 month and to 32% at 4 years. Device type (ICD vs PPM) and the number of leads placed did not have an effect on postimplantation TR (P > 0.2). Right ventricular systolic pressure (RVSP) did not change over time (36 mm Hg baseline, 37.5 mm Hg by 3 months, and 37 mm Hg by 1 year). One-year and 5-year survival were 93% and 73%, respectively. Postimplantation TR was an independent risk factor for late death (P < 0.05). Conclusion Cardiac device implantation was associated with a small but significant increase in the prevalence of moderate and severe TR, both acutely and chronically after implantation. The increase in TR was similar with both ICD and PPM placement, which was not related to the number of leads implanted and not associated with a significant increase in RVSP. Postimplantation TR was associated with a higher risk of mortality.

Introduction: A direct comparison of survival benefits between cardiac resynchronization therapy-pacemaker (CRT-P) and defibrillator (CRT-D) was not yet performed, leaving clinicians to question whether CRT-P alone is enough to protect congestive heart failure (CHF) patients from sudden cardiac death and whether CRT-D should be implanted to all CHF patients indicated for biventricular pacing. This study attempts to make this type of comparison in a large CHF population and seeks to identify predictors of death in patients with different comorbidities. Methods and Results: Study population consisted of 542 consecutive patients who were implanted with either CRT-P (N = 147) or CRT-D (N = 395) between 1999 and 2005. Patients' clinical and follow-up data were entered in a prospective registry and retrieved for analysis. The primary endpoint of this study was all-cause mortality during follow-up. Total all-cause mortality was significantly lower among patients with CRT-D (18.5% vs. 38.8% of CRT-P, χ2= 25.11, P < 0.001). Patients with one of three comorbidities—chronic renal failure (OR = 4.885, P = 0.005), diabetes mellitus (OR = 4.130, P = 0.003), and history of atrial fibrillation (OR = 1.473, P = 0.036)—appeared to have higher risk of death, while treatment with beta-blocker (OR = 0.330, P = 0.002) or CRT-D device (OR = 0.334, P = 0.003) seemed to be associated with lower mortality. Conclusions: Data from this nonrandomized study indicate that CRT-D has additional survival benefits over CRT-P. Given these findings, CRT-D should be recommended to most CHF patients with indications for biventricular pacing. After CRT implant, chronic renal failure, diabetes mellitus, and history of atrial fibrillation are strong independent predictors of death.

High defibrillation thresholds (DFTs) occasionally are encountered during placement of implantable cardioverter defibrillators (ICDs). There are multiple strategies to lower DFTs in such patients, including reassessment of right ventricular lead position, alteration of the shock waveform, and implantation of subcutaneous arrays. This article describes a novel technique of implanting a high-voltage lead in the azygos vein. This procedure may serve as an adjunctive approach to reduce DFTs. The anatomic location of the azygos vein posterior to the heart provides a suitable shocking vector between the right ventricular electrode, a high-voltage lead placed in the azygos vein, and the ICD can. (J Cardiovasc Electrophysiol, Vol. 15, pp. 780-783, July 2004)

There are limited and conflicting data regarding the prevalence of tricuspid regurgitation (TR) after cardiac device implantation (implantable cardioverter defibrillator [ICD]; permanent pacemaker [PPM]).The goal of this study was to assess the prevalence of TR after cardiac device implantation and determine its clinical significance.A total of 1,596 patients, who had cardiac devices implanted between 2005 and 2011 at the Cleveland Clinic and had at least one preimplantation echocardiogram and at least one postimplantation echocardiogram were included in this study. A total of 3,566 postimplantation echocardiograms were available for the 1,596 patients (median follow-up 10 months). The primary end point was postimplantation TR and the secondary end point was all-cause mortality after implantation. We have used a cumulative logistic nonlinear mixed-effects model to assess the temporal trend of TR prevalence and a parametric multiphase hazard model to assess survival.Of the 1,596 patients (mean age: 60 ± 10 years, 61% of patients were men), 985 (62%) had ICDs (including 334 patients with cardiac resynchronization therapy defibrillator) and 611 (38%) had PPMs. The prevalence of grade 3 or 4+ TR increased from 27% to 31% by 1 month and to 35% at 4 years. Accordingly, prevalence of grade 0/1+ TR decreased from 46% preimplantation to 37% at 1 month and to 32% at 4 years. Device type (ICD vs PPM) and the number of leads placed did not have an effect on postimplantation TR (P0.2). Right ventricular systolic pressure (RVSP) did not change over time (36 mm Hg baseline, 37.5 mm Hg by 3 months, and 37 mm Hg by 1 year). One-year and 5-year survival were 93% and 73%, respectively. Postimplantation TR was an independent risk factor for late death (P0.05).Cardiac device implantation was associated with a small but significant increase in the prevalence of moderate and severe TR, both acutely and chronically after implantation. The increase in TR was similar with both ICD and PPM placement, which was not related to the number of leads implanted and not associated with a significant increase in RVSP. Postimplantation TR was associated with a higher risk of mortality.

CRT benefits those patients with advanced heart failure with LV conduction delay as measured by QRS duration (QRSd). An increase in QRSd, however, may result from a combination of electrical delay and mass effect from LV dilation. This balance may be variable such that patients with a small LV and a

In the Antiarrhythmics Vs Implantable Defibrillators (AVID) trial, all patients who meet the study entry criteria are followed in a registry. During the period between June 1993 and June 1995, of 1,117 patients who were enrolled in the registry and met the study entry criteria, 476 were randomized to receive either implantable cardioverter-defibrillators (ICDs) or drug therapy (amiodarone or sotalol), and 641 patients were not randomized for a variety of reasons including: patient refusal (42%); physician refusal (43%); concerns about ability to maintain follow-up over several years (10%), and others (6%). There were no significant differences between the 476 randomized and 641 nonrandomized patients with regard to clinical characteristics, left ventricular function, history of congestive heart failure, medical history, and previous cardiac procedures performed before the index event, except that randomized patients were slightly older (65 vs 62 years) and had a slightly higher prevalence of coronary artery disease and previous myocardial infarction. The index event and location of the index event were not significantly different between the 2 groups. Although 14% of registry patients received neither ICD nor antiarrhythmic drug therapy, ICDs were no more frequently used in the registry patient than antiarrhythmic drugs (45% for ICD vs 42% for drugs). Thus, randomized AVID patients have very similar clinical characteristics, cardiac history, and presenting arrhythmias as to nonrandomized eligible patients. Therefore, the results of the AVID trial may be generalized for all patients with AVID-eligible arrhythmias.

Cardiac resynchronization (CRT) is associated with reverse ventricular remodeling and improved clinical outcomes, but is not successful in all patients. We looked at the feasibility of combined non-invasive imaging of the coronary veins and assessment of left ventricular dyssynchrony prior to pacemaker implantation and whether this combination would improve procedural success and patient outcome. Heart failure patients with standard indications for CRT were randomized to cardiac Multi-Detector CT (MDCT) plus Doppler echocardiographic assessment of left ventricular dyssynchrony versus conventional management prior to CRT. Co-registration of MDCT and tissue synchronization imaging data using a novel software program was performed and the results were used to optimize left ventricular lead placement for patients in the non-invasive imaging arm. 21 patients were enrolled with 9 patients randomized to the contemporary non-invasive imaging strategy and 12 patients randomized to the control group. MDCT correctly identified 19 of 24 (79%) coronary venous branches ≥ 2 mm in diameter when compared to invasive coronary venography. Patients in the non-invasive imaging group had a significant improvement in the 6 minute walk time on 6 month follow up (76.1 ± 48.4 meters vs 20.0 ± 64.8 meters, p = 0.04). Improvements in NYHA functional class and LV remodeling at 6 months were not significantly different in the non-invasive imaging and control arms. Left ventricular lead placement was successful in all patients, however more patients in the non-invasive imaging arm demonstrated LV lead placement in the most delayed or adjacent myocardial segment (8 of 9 vs 6 of 12, p = 0.09). Those patients with “optimal” lead placement showed a trend towards improved 6 minute walk times and improvement in left ventricular function 6 months after biventricular pacing. An imaging-guided strategy with coregistration of MDCT coronary venous anatomy and delayed myocardial segments by tissue Doppler echocardiography prior to CRT is feasible and may improve patient outcomes by facilitating optimal LV lead placement.

A surface electrocardiogram (SECG) for pacing threshold measurements during routine implantable cardioverter-defibrillator (ICD) follow-up can be cumbersome. This study evaluated the use of an intrathoracic far-field electrogram (EGM) derived between the Can and superior vena cava (SVC) electrode -- the Leadless electrocardiogram (LLECG), in dual chamber ICDs in performing pacing threshold tests.The LLECG was evaluated prospectively during atrial and ventricular pacing threshold testing as a substudy of the Comparison of Empiric to Physician-Tailored Programming of Implantable Cardioverter-Defibrillators trial (EMPIRIC) in which dual chamber ICDs were implanted in 888 patients. Threshold tests were conducted at 1 volt by decrementing the pulse width. Follow-up at three months compared pacing thresholds measured using LLECG with those using Lead I of the surface ECG (SECG). The timesaving afforded by LLECG was assessed by a questionnaire.The median threshold difference between LLECG and SECG measurements for both atrial (0.00 ms, P = 0.90) and ventricular (0.00 ms, P = 0.34) threshold tests were not significant. Ninety percent of atrial and ventricular threshold differences were bounded by +/- 0.10 ms and -0.10 to +0.04 ms, respectively. We found that 99% of atrial and ventricular thresholds tests at six and 12 months attempted using LLECG were successfully completed. The questionnaire indicated that 65% of healthcare professionals found LLECG to afford at least some timesaving during device follow-ups.Routine follow-up can be performed reliably and expeditiously in dual chamber Medtronic (Minneapolis, MN, USA) ICDs using LLECG alone, resulting in overall timesaving.

DETECTION OF SVT WITH DUAL CHAMBER VERSUS SINGLE CHAMBER DETECTION ENHANCEMENTS (THE DETECT SVT TRIAL) Paul A. Friedman, MD, Helbert Acosta, MD, David Kessler, MD, Thomas M. Munger, MD, Neal G. Kavesh, MD, Mark Wood, MD, Emile Daoud, MD, Ali Massumi, MD, Claudio Schuger, MD, Stephen Shorofsky, MD, Bruce Wilkoff, MD, Michael Glikson, MD, for the DETECT SVT investigators. Mayo Clinic, Rochester, MN, Trinity Medical Center, Rock Island, IL, Austin Heart, Austin, TX, Watson Clinic, Lakeland, FL, Virginia Commonwealth University, Richmond, VA, MidWest Research Foundation, Columbus, OH, Texas Heart Institute, Houston, TX, Henry Ford Hospital, Detroit, MI, University of Maryland Baltimore, Baltimore, MD, Cleveland Clinic, Cleveland, OH, Sheba Medical Center, Tel Aviv, Israel.