Do Steroid-Eluting Electrodes Really Have Better Performance Than Other State-of-the-Art Designs?

A multicenter study evaluated the performance of atrial and ventricular unipolar leads with porous steroid-eluting and platinized grooved electrodes. A total of 563 leads were implanted in 451 patients. These included 311 ventricular and 97 atrial steroid-eluting electrodes; and 112 ventricular and 43 atrial leads with platinized electrodes. Mean follow-up was ± 1 year. At implant there were no significant differences in threshold parameters in either chamber. Chronically, however, the steroid eluting lead consistently had significantly lower pacing thresholds in both chambers. For example, after 360 days implant, steroid-eluting electrodes had 0.23 ± 0.10 msec ventricular thresholds at 0.8 V compared to 0.45 ± 0.3 msec in the platinized group (P < 0.0001). In the atrium, the steroid-eluting lead's 6-month thresholds at 0.8 V were 0.15 ± 0.06 msec compared to 0.9 ± 0.8 msec for the platinized electrode (P < 0.01). The chronic ventricular QRS amplitudes were significantly greater for the steroideluting electrode (P < 0.0005). There were no significant differences in atrial sensing and no incidence of atrial undersensing in the study. The low and consistent thresholds of the steroid-eluting electrodes would have permitted pacing in the ventricle at ± 2.5 V without compromising safety factor in 99.4% of the patients. The other 0.6% required 5 V temporarily. In the atrium, 100% of the patients could have been paced safely at reduced output. In spite of this, 63% of the implanters lacked the confidence to use reduced outputs.     

An echocardiographic method for selecting high risk patients shortly after acute myocardial infarction, for inclusion in multi-centre studies (as used in the TRACE study)

The aim of our study was to examine if echocardiography canreproducibly be used in a multicentre study to select high riskpatients with reduced left ventricular function early afteran acute myocardial infarction (MI). In the TRAndolapril Cardiac Evaluation Study (TRACE) patientswith reduced left ventricular systolic function were randomized3–7 days post MI to receive either the ACE inhibitor trandolapril,or placebo. Twenty-seven Danish centres participated and 7001consecutive MI patients were screened for entry. Local doctorsand technicians who had received a brief but thorough trainingcourse recorded a two-dimensional echocardiographic examinationon videotape 2–6 days after MI. Within 24 h, wall motionindex (WMI) was visually assessed by one of two cardiologists(examiners) with considerable experience in echocardiography.A WMl of l.2 (corresponding to a left ventricular ejection fraction(LVEF) 0.35) meant that the patient was eligible for randomizationin the TRACE study. Two other experienced cardiologists withsubstantial experience in echocardiography (controllers) performedblind reassessment of 155 randomly chosen videotapes. We showed that 93% of the 7001 screened Mis had an assessableechocardiogram. WMl was 1.2 in 37% of patients. The one-yearmortality was inversely related to WMl, being 60%, 30%, 14%and 11% in patients with a WMI<0.8, 0.8–1.2, 1.3–1.6and >l.6, respectively. In the random sample of 155 videorecordingsthat were reevaluated, 97% were found to be technically adequatefor analysis both by the examiners and the controllers. Comparingthe examiners with the controllers, the reproducibility analysisshowed 95% confidence limits for a single estimate of LVEF of± 0.13. Comparison between the two examiners showed correspondingconfidence limits of ±0.10. Using WMl of 12 (LVEF0.35)as a discriminative value the concordance between examinersand controllers was 80%. Thus, evaluation by experienced cardiologists of videotapedechocardiographic examinations recorded by briefly but thoroughlytrained investigators appears to be a reliable and reproduciblemethod for the selection of high risk patients shortly afterMI in multicentre studies.