Introduction: Most of the data supporting catheter ablation of atrial fibrillation (AF) come from trials performed at academic centers that enrolled mostly men. A few centers have reported that fem...

Background: A total of 405 participants in the Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure trial were prospectively enrolled in an exercise sub-study designed to study the influence of cardiac resynchronization therapy (CRT) on measures of exercise capacity, functional capacity, and quality of life (QOL).Methods and Results: Substudy eligibility included New York Heart Association (NYHA) functional Class III or IV heart failure, left ventricular ejection fraction <= 0.35, QRS interval of >= 120 ms, normal sinus rhythm, a heart failure hospitalization (or equivalent) within 1 year, a peak VO2 <= 22 mL.kg.min, the ability to walk 150 to 425 meters in 6 minutes, forced expiratory volume in 1 second/forced vital capacity >= 50%, and no clinical indication for a pacemaker or implantable cardioverter-defibrillator. Patients were randomized in a 1:4 ratio to optimal medical therapy (OPT) or to OPT plus CRT. Cardiopulmonary exercise testing (peak VO2 and 6-minute walk distance [6MWD]) and assessment of NYHA functional class and QOL were assessed at baseline and at 3 and 6 months of assigned therapy. There was no significant improvement in peak VO2 at 6 months in the CRT group compared with the OPT group (+0.63 mL.kg.min) by unadjusted analysis (P = .05) or by analyses adjusted for missing data. Thus the primary end point of the study was not met. There was significantly greater improvement in the 6MWD in the CRT group compared with the OPT group at both 3 and 6 months by both statistical methods (P <= .045). Likewise, a greater proportion of CRT patients improved by 1 or more NYHA functional classes (P < .01) at 3 months and had better QOL scores (P < .01) at 3 and 6 months compared with the OPT patients. Baseline peak VO2 predicted clinical events (time to death, time to death or first hospitalization, or time to death and first heart failure hospitalization: P < .05) in CRT participants.Conclusion: CRT patients with moderate to advanced symptoms of systolic heart failure and prolonged QRS intervals benefit from the addition of CRT to OPT in terms of exercise capacity, functional status, and QOL. CRT should be considered standard therapy in this select group of heart failure patients.

Background - Cardiac resynchronization therapy ( CRT) alone or combined with an implantable defibrillator ( CRT-D) has been shown to improve exercise capacity and quality of life and to reduce heart failure ( HF) hospitalizations and mortality in patients with New York Heart Association ( NYHA) class III and IV HF. There is concern that the device procedure may destabilize these very ill class IV patients. We sought to examine the outcomes of NYHA class IV patients enrolled in the Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure ( COMPANION) trial to assess the potential benefits of CRT and CRT-D.Methods and Results - The COMPANION trial randomized 1520 patients with NYHA class III and IV HF to optimal medical therapy, CRT, or CRT-D. In the class IV patients ( n = 217), the primary end point of time to death or hospitalization for any cause was significantly improved by both CRT ( hazard ratio [ HR], 0.64; 95% CI, 0.43 to 0.94; P = 0.02) and CRT-D ( HR, 0.62; 95% CI, 0.42 to 0.90; P = 0.01). Time to all-cause death and HF hospitalization was also significantly improved in both CRT ( HR, 0.57; 95% CI, 0.37 to 0.87; P = 0.01) and CRT-D ( HR, 0.49; 95% CI, 0.32 to 0.75; P = 0.001) Time to all-cause death trended to an improvement in both CRT ( HR, 0.67; 95% CI, 0.41 to 1.10; P = 0.11) and CRT-D ( HR, 0.63; 95% CI, 0.39 to 1.03; P = 0.06). Time to sudden death appeared to be significantly reduced in the CRT-D group ( HR, 0.27; 95% CI, 0.08 to 0.90; P = 0.03). There was a nonsignificant reduction in time to HF deaths for both CRT ( HR, 0.68; 95% CI, 0.34 to 1.37; P = 0.28) and CRT-D ( HR, 0.79; 95% CI, 0.41 to 1.52; P = 0.48).Conclusions - CRT and CRT-D significantly improve time to all-cause mortality and hospitalizations in NYHA class IV patients, with a trend for improved mortality. These devices should be considered in ambulatory NYHA class IV HF patients similar to those enrolled in COMPANION.

OBJECTIVES The purpose of this study was to analyze defibrillation conversion data from the Low Energy Safety Study (LESS) to determine how implant criteria that use fewer inductions of ventricular fibrillation (VF) correlate with outcome and, in particular, to assess the reliability of using a single VF induction and test shock at 14 J.BACKGROUND A safety margin of 10 J has become standard for implantation of an implantable cardioverter-defibrillator (ICD), but the specifics and rigor of the implant test sequence are not standardized.METHODS In LESS, 611 ICD recipients completed a rigorous VF induction test scheme that began at 14 J and continued until the energy that succeeded three times without a failure was determined (DFT++). The data were analyzed to determine how well the outcome of the first 14-J shock and various other combinations of first and/or second shocks predicted a rigorous gold standard of DFT++ less than or equal to;21 J (i.e., three successes at less than or equal to 21 J).RESULTS The positive predictive accuracy for the 91% of patients in whom the first 14-J shock succeeded was virtually identical to the positive predictive accuracy for the commonly used criteria of two successes at less than or equal to 17 J (99.1% vs 99.0%, P = .69), and slightly higher than the positive predictive accuracy for two successes at less than or equal to21 J (98.8%, P= .51). A single success at 17 J or 21 J had a somewhat lower.positive predictive accuracy of 98.2% (P =.17). Eliminating VF induction testing would have resulted in a significantly lower positive predictive accuracy of 97.1 % (P =.0 1).CONCLUSIONS A single conversion success at 14 J on the first VF induction provides similar positive predictive accuracy as two successes at 17 J or 21 J. Using this criterion, 91% of patients meet implant criteria with a single induction of ventricular fibrillation.

A 23-year-old woman was referred for episodes of recurrent syncope. Electrocardiogram, echocardiogram, 24-hour Holter monitor, 30-day event monitor, and tilt table test were all normal or nondiagnostic. Electrophysiologic testing was performed. Conduction intervals were normal. There were no inducible atrial or ventricular tachyarrhythmias. During atrial pacing at a cycle length of 380 msec, the phenomenon shown

This placebo-controlled, double-blind, longitudinal crossover study compares the efficacy of disopyramide and ethmozine, a new investigational drug, in suppressing frequent (40 or more per hour) ventricular premature depolarizations (VPDs) in 27 patients completing a 37 day protocol. Although both drugs significantly reduced VPDs relative to placebo, ethmozine was a superior antiarrhythmic drug in achieving near-total abolition of VPDs (30% of patients), which was never observed during disopyramide dosing (p < .05). At the 80% VPD reduction level, ethmozine was effective in 56% of all patients compared with an effectiveness in only 22% of patients during disopyramide therapy (p < .05). The mean peak plasma level of ethmozine was 0.66 + 0.8 gg/ml, which significantly fell to a trough level of 0.1 + 0.08 gg/ml (p < .001). Mean peak and trough plasma levels of disopyramide exhibited less fluctuation (2.6 + 0.9 ,ug/ml vs 2.2 0.9 gg/ml). Ethmozine had no effect on the QTC interval, whereas disopyramide prolonged it significantly. Importantly, while disopyramide produced serious side effects in 30% of patients, ethmozine was well tolerated with no statistically significant side effects compared with placebo. Circulation 69, No. 2, 288-297, 1984. EPIDEMIOLOGIC STUDIES in which 12-lead electrocardiograms have been used have documented an increased risk of sudden cardiac death in patients with coronary heart disease who have ventricular premature depolarizations (VPDs). 1-3 Ambulatory electrocardiographic recording has allowed a more systematic and complete quantification of these ventricular arrhythmias that are predictive of sudden cardiac death, especially in patients surviving myocardial infarction.±7 The currently available antiarrhythmic drugs include the /3-blockers, some of which have well-defined efficacy for suppressing VPDs.8'9 A number of multiFrom the Section of Cardiology, Department of Medicine, Baylor College of Medicine and The Methodist Hospital, Houston. Supported in part by the Biomedical Research Support Grant, P-14, General Clinical Research Center, The Methodist Hospital, and a grant from DuPont Pharmaceuticals, Wilmington, DE. Computational assistance was provided by the CLINFO project funded by grant RR-00350, Division of Research Resources, National Institutes of Health, Bethesda. Address for correspondence: Craig M. Pratt, M.D., The Methodist Hospital, Baylor College of Medicine, 6535 Fannin, MS FIOOI, Houston, TX 77030. Received Aug. 24, 1983; revision accepted Oct. 27, 1983. 288 center clinical trials using /3-blockers for patients in the late-hospitalization phase of acute myocardial infarction have shown an overall reduction of sudden cardiac death. I"2 None of these multicenter trials were designed specifically to define the mechanism of this reduction in sudden cardiac death that presumably was a result of preventing sustained ventricular tachycardia and ventricular fibrillation.'3 '4 The classical type I antiarrhythmic drugs (procainamide, quinidine, and disopyramide) are widely used to suppress ventricular rhythm disturbances. While effective in reducing the frequency of VPDs in many patients, all of these drugs have serious side effects. In addition to these undesirable side effects, all three have been documented to cause torsades de pointe ventricular tachycardia. 15-17 A recent report by Velebit et al. 18 documents the frequency with which antiarrhythmic drugs aggravate ventricular rhythm disturbances, with the highest reported frequency caused by quinidine (15.8%). Disopyramide (Norpace, Searle Pharmaceuticals, Inc.; Chicago) is a recent addition to the type I antiarrhythmic group. Its development as an effective antiar-

Background A 10-J energy safety margin has traditionally been used in programing implantable cardioverter defibrillators (ICDs). The Low Energy Safety Study (LESS) tests the hypothesis that programing shocks to lower energy margins is safe and effective. Methods Patients with standard ICD indications undergo defibrillation threshold testing (DFT) at the time of ICD implant, with reconfirmation of lowest successful energy twice (DFT++). Patients are randomized to 2 groups: the first has the initial 2 shocks for ventricular fibrillation conversion programed at 2 energy steps above DFT++ (typically 4-6 J, maximum 10 J) with subsequent shocks at maximum energy, and the second has all shocks programed at maximum energy. Patients are followed up every 3 months for 2 years to assess shock conversion efficacy of spontaneous arrhythmias. In a subgroup of patients, there is a second randomization to energy levels of 0, 1, 2, 3, or 4 steps above implant DFT++ for conversion testing of 3 induced ventricular fibrillation episodes at prehospital discharge, 3 months, and 12 months after implant. Results Enrollment is complete (702 patients), but follow-up results are pending. There were no significant variations in implant indications and baseline antiarrhythmic drug use over the 3-year enrollment period, although an increase in the percentage of dual-chamber ICDs implanted occurred, with the majority (65%) of implanted ICDs being dual-chamber devices by the end of the enrollment period. Conclusion The results of LESS should facilitate the development of algorithms for programing ICD energy safety margins. (Am Heart J 2002;143:199-204.)

The Medtronic Jewel PCD model 7219, introduced in 1994, was the first downsized, pectoral implantable cardioverter defibrillator (ICD), and many of these units are approaching or have reached the elective replacement indicator (ERI). Unlike later Medtronic ICDs and most other ICDs, in which ERI is defined by battery voltage, the ERI in the model 7219 series is defined when either the capacitor charge time to full output is repeatedly≥14.5[emsp4 ]s or when battery voltage is≤4.91[emsp4 ]V. In this study we examined which of the two ERI criteria was met first in patients with this device model. We also assessed the effects of manual dumping and recharging and of increasing the automatic capacitor reformation frequency on prolonged charge times. In 16 patients with follow-up <2 years, 15 reached the charge time ERI before battery voltage ERI. Manual dumping and recharging led to spuriously low charge times due to residual charge at the start of recharging, and increasing the automatic capacitor reformation frequency to once a month did not decrease prolonged charge times. Because of persistently prolonged charge times, 15 patients had generator changes. None of these patients had reached battery voltage ERI (battery voltage at time of explantation 5.06±0.06[emsp4 ] V). Thus in this early pectoral device, prolonged charge times occur commonly before battery voltage ERI is reached. Whether prolonged charge times will have an impact on device longevity in later model ICDs is unknown.

We compared the incidence of oversensing of myopotentials during bradycardia pacing in implantable cardioverter-defibrillators from 3 different manufacturers, with 3 different types of sensing systems. The Ventritex sensing system, which uses maximum gain continuously during bradycardia pacing, had a higher incidence of oversensing (24% of patients) than the sensing systems of CPI (3%) or Medtronic (0%), suggesting that the Ventritex sensing system may be unsuitable for use in a dual-chamber defibrillator.

Capacitor charging accounts for most of the delay between arrhythmia detection and therapy delivery in ICDs. Long capacitor charge times may increase the risk of syncope in patients with poorly tolerated arrhythmias. To determine if there are clinically important differences in charge time among currently available devices, we analyzed charge times at various delivered energy levels in three manufacturers’devices: Medtronic, CPI, and Ventritex, Charge times were measured for shocks delivered for spontaneous or induced arrhythmias occurring from time of implant to 4 months after implant. A total of 343 shocks were assessed in 63 patients with ICDs: 16 Medtronic (Microfewel II, model 7223Cx). 14 CPI (Mini II, model 1762), and 33 Ventritex (Cadet and Contour, models V‐115 and V‐145). The curves of the relationship between charge time and delivered energy for the three types of devices were significantly different, with Medtronic charge times shorter than CPI or Ventritex (P < 0.0001), and CPI charge times shorter than Ventritex (P ‐ 0.002). The difference in mean charge times between the Ventritex and Medtronic devices ranged from 1.7 seconds at a delivered energy of 10 ± 2.5 J to 8,0 seconds at a delivered energy of 30 ± 2.5 J. Thus, clinically important differences in charge time exist among the three types of defibrillators studied. These results should be considered in selecting an ICD for patients with poorly tolerated arrhythmias.

Implantable cardioverter defibrillator undersensing leading to delayed or aborted therapy delivery has been reported with induced arrhythmias and following failed defibrillator shocks. We describe a case in which spurious redetection of sinus rhythm during a spontaneous episode of ventricular fibrillation resulted in aborted device therapy.

This paper traces the development of a Common Enumeration of Vulnerabilities and Exposures (CVE) that standardizes and lists vulnerabilities and security exposures to facilitate data sharing and comparison across computer vulnerability databases, such as those produced by security tools and academic research. The MITRE Corporation is building a syste m that can integrate and manage vulnerability information from different sources (e.g., network assessment tools, intrusion detection systems [IDSs], archives) in a database for supporting enterprise security operations. However, every information security tool considered for integration has its own vulnerability database. Also, the lack of common naming conventions and a common enumeration of the vulnerabilities in the vulnerability databases hindered integration efforts. Thus, MITRE developed CVE to provide a common vocabulary for its vulnerability database system effort. CVE provides a mechanism for information security community discussion on vulnerability identification and other related security issues. CVE development was broadened by creating a CVE Editorial Board, which includes information security community representatives from tool vendors, research and educational organizations, MITRE, and others. The CVE Editorial Board is currently enumerating a large number of vulnerabilities, while simultaneously attempting to capture and codify the decision-making process. When a significant number of vulnerabilities are validated and verified, an initial version of CVE will be released to the public. The document includes background information on MITRE's early CVE activities, a draft CVE design, CVE content and use, and lessons learned.

Radiofrequency catheter ablation has been used to treat idiopathic left ventricular tachycardia with high success rates. The majority of reported cases have exhibited the typical findings of right bundle branch block morphology with left axis deviation and originate from within or near the left posterior fascicle. We report a case of idiopathic left ventricular tachycardia originating from within or near the left anterior fascicle, which was successfully ablated using a local Purkinje potential as a guide.

We report a patient who Received a CPI Ventak AV II DR ICD for ventricular tachycardia and complete heart block without an escape rhythm. During induced nonsustained ventricular tachycardia, the device, although programmed to deliver noncommitted shocks, acted like a committed device. This phenomenon is due to undocumented behavior that is likely to occur in any patient who is pacemaker dependent and has nonsustained ventricular tachycardia.

Background During bradycardia pacing in Ventritex Cadence (Models V-100 and V-110) implantable cardioverter-defibrillators, amplifier gain is maximal and oversensing and false tachyarrhythmia detection have been reported. Newer Ventritex devices (Cadet, Model V-115 and Contour, Model V-145) have a modified automatic gain control that may minimize oversensing. Methods and Results We prospectively studied 50 patients (22 with Cadence, 28 with Cadet or Contour). Electrograms were evaluated for oversensing during bradycardia pacing. The bradycardia pacing refractory period required to prevent oversensing of T waves of paced beats and the time and number of beats required to achieve minimum gain after cessation of pacing were assessed. The bradycardia pacing refractory period could be left at its default setting of 350 ms in only 15 (30%) of 50 patients. The mean bradycardia pacing refractory period required to avoid oversensing of paced T waves was 386 ± 32 ms. During pacing, oversensing of nonpaced T waves was seen in 12 (24%) devices, with similar incidence in Cadence devices (18%) and Cadet and Contour devices (29%, p = not significant). The time and number of beats to achieve minimum gain after pacing were longer in Cadence devices (19.0 ± 4.5 vs 4.6 ± 1.2 sec; 21.3 ± 3.3 vs 5.0 ± 0.4 beats, both p < 0.001). Conclusions The incidence of oversensing at maximum gain is similar in both types of devices, but more rapid changes in autogain levels in the newer devices may reduce the likelihood of false tachyarrhythmia detection. (Am Heart J 1998;136:658-63.)

Spontaneous variability over time in the ease of induction of ventricular arrhythmias may mimic a drug effect and affect the predictive value of drug therapy guided by programmed stimulation. We assessed the effect of baseline reproducibility of arrhythmia induction on the incidence and accuracy of drug efficacy predictions in the Electrophysiologic Study Versus Electrocardiographic Monitoring (ESVEM) trial. Patients with sustained ventricular tachyarrhythmias induced twice during baseline electrophysiologic testing with the same stimulation technique, i.e., induced at the same pacing site with the same drive cycle length and number of extrastimuli, were identified from the ESVEM database. These patients with highly reproducible arrhythmia induction were compared to those with less reproducible arrhythmias. Of 473 randomized patients with reproducibility data, 313 (66%) had highly reproducible arrhythmias. In patients randomized to electrophysiologic testing, baseline arrhythmia reproducibility did not affect the incidence of drug efficacy predictions (70 of 157 [45%], drug efficacy predictions in patients with highly reproducible arrhythmias vs 34 of 79 [43%] with less reproducible arrhythmias, p = 0.890). Drug efficacy predictions obtained by electrophysiologic testing in patients with highly reproducible arrhythmias were not associated with decreases in arrhythmia recurrence (p = 0.202), all-cause mortality (p = 0.301), cardiac death (p = 0.358), or arrhythmic death (p = 0.307) compared to those with less reproducible arrhythmias. Analysis of patients with highly reproducible sustained monomorphic ventricular tachycardia led to similar results. In the ESVEM trial, most patients had highly reproducible arrhythmia induction during baseline electrophysiologic testing. Reproducibility of arrhythmia induction in the baseline state had no effect on the incidence or accuracy of drug efficacy predictions.