Clinical outcomes after upgrading from pacemakers to cardiac resynchronization therapy

1 Background and aims

Right ventricular pacing may lead to heart failure (HF). Upgrades from pacemakers to cardiac resynchronization therapy (CRT) were excluded from most randomized, controlled trials. We sought to determine the long‐term outcomes of upgrading from pacemakers to CRT with (CRT‐D) or without (CRT‐P) defibrillation in patients with no history of sustained ventricular arrhythmias.

2 Methods and results

In this observational study, clinical events were quantified in relation to the type of implant (de novo or upgrade) and device type at upgrade (CRT‐P or CRT‐D). Patients underwent CRT implantation (n = 1,545; 1,314 [85%] de novo implants and 231 [15%] upgrades) over a median of 4.6 years [interquartile range: 2.4–7.0]. In analyses of crude event rates, upgrades had a higher total mortality (adjusted hazard ratio [aHR]: 1.33; 95% confidence interval [CI] 0.10–1.61), a higher total mortality or HF hospitalization (aHR: 1.26; 95% CI 1.05–1.51), but similar mortality or hospitalization for major adverse cardiac events (MACEs, aHR: 1.15; 95% CI 0.96–1.38). No group differences emerged in any of these endpoints after propensity score matching. After inverse probability weighting in upgrades, total mortality (HR: 0.55; 95% CI 0.36–0.73), total mortality or HF hospitalization (HR: 0.56; 95% CI 0.34–0.79), and total mortality or hospitalization for MACEs (HR: 0.61; 95% CI 0.40–0.82) were lower after CRT‐D than after CRT‐P.

3 Conclusion

Upgrading from pacemakers to CRT was associated with a similar long‐term risk of mortality and morbidity to de novo CRT. After upgrade, CRT‐D was associated with a lower mortality than CRT‐P.     

I NTRODUCTION TO F IRE P REVENTION,F IFTH E DITION

Objectives: To determine whether members of a ski patrol, most of whom have no off-season medical responsibilities, can successfully complete an automated external defibrillator (AED) training program prior to the ski season, and retain AED skills at the end of the season and at the beginning of the following season. Methods: A prospective educational study was conducted with 61 ski patrol personnel: 51 (84%) had no other medical training, 44 (72%) had no off-season medical duties, and 57 (93%) had no prior exposure to AEDs. Prior to the ski season (December 1, 1998), all members were trained and tested using the standard American Heart Association (AHA) AED training package and a Life-Pak 500 AED and AED Trainer donated by the Medtronic Physio-Control Corporation. Both after the ski season (April 1, 1999) and prior to the following season (October 30, 1999), with no refresher training, participants were retested with the same written and practical exams. Cochrane's linear trend test was used to compare scores on the practical and written tests over time. Results: For the three testing sessions, practical test pass rates were 95%, 92%, and 97%, and written test pass rates were 100%, 98%, and 98%. There was no change in individuals' scores on either the written test (p = 0.914) or the practical test (p = 0.413) over time. Conclusions: A heterogeneous group of ski patrollers can successfully complete an AED training course, with good skill retention both after the ski season and at the beginning of the following season.     

Cardiac injury with damped sine and trapezoidal defibrillator waveforms

To assess defibrillator-induced cardiac damage, 49 anaesthetized greyhounds received either no shocks (control group) or five shocks from a defibrillator delivering one of five waveforms (Lown, Edmark, Belfast damped sine waveforms: 5 and 20 ms trapezoidal waveforms). At 3 days the hearts of the 36 surviving dogs were examined for macroscopic damage. The Belfast and Edmark waveforms caused significantly more damage (mean 21.1 +/- SEM 2.9 g and 16.0 +/- 3.7 g) respectively than the Lown waveform (3.5 +/- 1.3 g) P less than 0.01. The 20 ms trapezoid caused significantly more damage (8.1 +/- 3.1 g) than the 5 ms pulse (0.7 +/- 1.3 g) P less than 0.05). The ventricular ectopic counts per minute were not significantly different in the three sine wave and 20 ms trapezoidal groups at 24 and 48 h (P greater than 0.05), but at 2 and 72 h were significantly greater in the Belfast and Edmark groups than in the Lown group (2 h, Belfast P less than 0.01, Edmark P less than 0.05: 72 h P less than 0.05). At 15 min there was more right chest ST-segment elevation in the Belfast than in the Lown, Edmark and 20 ms trapezoid groups (P less than 0.01), while left chest ST elevation was greater in the Belfast and Edmark than in the Lown (P less than 0.05) and 20 ms trapezoid groups (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

ACCF/AHA肥厚型心肌病诊断治疗指南2011解读

肥厚型心肌病是一种常见的心血管疾病。该指南是由美国心脏病学院基金会(ACCF)和美国心脏协会(AHA)联合推出的第一部关于肥厚型心肌病的指南。现就指南中涉及到肥厚型心肌病定义、诊断方法、病程特点以及治疗手段进行概括及解读。     

Is Inappropriate Implantable Defibrillator Shock Therapy Predictable?

Objective: To identify implantable cardioverter defibrillator (ICD) patients who are at risk of receiving inappropriate shock. Background: Inappropriate ICD shock, usually from atrial fibrillation (AF) or sinus tachycardia (ST), is a common problem. We hypothesized that clinical variables would predict which patients with single chamber ICDs would be more likely to receive inappropriate therapy and be candidates for more accurate discriminators such as those available in dual chamber ICDs. Methods: The ICD registry at St. Michael's Hospital has it's clinical information and demographic data updated after each clinic visit. Inappropriate shock was considered as the outcome variable. Possible predictors considered were age, gender, ejection fraction, NYHA class, prior CABG and prior history of AF. Univariate predictors were identified using t-test for continuous variables and Chi-square test for categorical variables. Multivariate predictors were identified using stepwise logistic regression analyses. Results: Of 299 patients, 261 had complete data for analysis. In this population 78% were male, mean age was 60 ± 13 years, mean ejection fraction was 37 ± 15% and mean follow up was 53 ± 36 months. One hundred and sixteen of the 261 patients (44%) received one or more inappropriate therapies (73% within 2 years of receiving their device), and 140 (51%) received one or more appropriate therapies. Significant predictors of inappropriate therapy by multivariate model were prior AF (OR 2.6, 95% CI 1.5–4.5) and NYHA class 1 vs. classes 2–4 (OR 2.2, 95% CI 1.2–3.7). Conclusion: Clinical characteristics of ICD patients can predict those at risk for inappropriate shock and should be considered for interventions to decrease such shocks.