Results of Trials Presented at Heart Rhythm 2010

Compiled by D. Sakellariou, May 17, 2010

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MADIT-CRT sub-study 1 (leads position and outcome)

According to a sub-study of the Multicenter Automatic Defibrillator Implantation Trial-CRT (MADIT-CRT), which was presented at the 31st Annual Scientific Sessions, left ventricular (LV) leads positioned in the apical region when compared to the mid-ventricular or basal regions are associated with a significantly increased risk of heart failure (HF) and death in patients receiving cardiac resynchronisation therapy (CRT). This sub-study evaluated the impact of left ventricular (LV) lead location on outcomes in 799 patients randomised to CRT-D in MADIT-CRT. The LV lead location was classified along the short axis into an anterior, lateral or posterior position, and along the long axis into a basal, mid-ventricular or apical region. After the follow-up period it was found that 22% of patients with an apical lead position had a significantly increased risk of HF and mortality compared to an average of 12% for patients with the mid-ventricular or basal position. In addition, the placement of LV leads along the anterior, lateral or posterior wall in CRT-D patients showed similar outcomes and extent of benefit from resynchronisation therapy.

MADIT-CRT sub-study 2 (cardiac resynchronisation therapy reduces all-cause mortality in females)

Another sub-analysis of the MADIT-CRT study, which was also presented in the Sessions, explored the factors associated with the better outcome of women who participated in the study. This sub-analysis found that females had a significantly better result from CRT-D than males, independently of QRS duration. Non-ischaemic cardiomyopathy and QRS duration <150 ms were the major contributing factors to the reduced heart failure/death endpoint in females. CRT-D was associated with a significant reduction in all-cause mortality in females (HR 0.34, p<0.01) but not in males (HR 1.02) with an interaction p-value of 0.048 between gender and device therapy for mortality.

Programming Strategies Associated With Shock Reduction In Patients With Implantable Defibrillator

This observational cohort analysis enrolled 88,804 patients with a CRT or a dual chamber (DR) ICD. The primary endpoint was the number of spontaneous all-cause shocked episodes per 100 patients/years. A priori, 4 shock reduction programming strategies as well as clinical characteristics were entered into a multivariable model including: slowest VT/VF detection threshold, VF number of intervals to detect (NID), SVT discriminators On, ATP On for Fast VTs (FVT), AF with rapid ventricular response (RVR): AF ≥1 hr for ≥1 day with average ≥110 bpm, gender, age, ICD type, ICD replacement. After the 2.5 ± 1.3 yrs follow up, there were 19,458 pts (22%) who had a total of 72,239 shocked episodes. After adjusting for all variables, the following results were found: 28% shock reduction with ATP activated for fast VT episodes; 22% shock reduction with SVT discriminators activated; 17-55% shock reduction depending on the duration of VT for detection; 21-148% shock reduction depending on the rate of VT detection limit. In addition, atrial fibrillation (AF) has a dramatic impact on the incidence of shocks and is dependent on the rapid ventricular rate (RVR) observed during the atrial fibrillation (244% increased shocks). This trial, which is the largest of its kind, found that clinical actions, such as adequate rate control for pts with AF as well as programming to increase the VT/VF detection rate and duration thresholds, reduce the number as well as the morbidity from shocks in patients with an ICD.

Remote Monitoring Dramatically Improves Time To Treatment And Detection Of Atrial Fibrillation In Elderly Patients

According to this randomised, prospective study, which is the first to consider using remote monitoring on elderly patients to detect and treat atrial fibrillation (AF), remote monitoring proves effective for earlier detection of arrhythmic events and pacemaker dysfunction in elderly patients with AF. In the study 267 patients age 60 years and older with atrioventricular pacemaker implantation were enrolled. Between March 2007 and September 2009, all patients were randomly assigned to a remote group (RG=135) and a control group (CG=132). Follow up with patients was conducted at months, 1, 3, 6, 12, 18 and 24, during which variables such as age, gender, follow-up time, time to AF diagnosis, AF burden and health complications (i.e. AF incidence, stroke) were analysed. Time to first AF detection was nearly twice as fast in patients in the RG (48 days in RG vs. 85 days in CG, p=0.047). The majority of AF episodes detected by remote monitoring (96%) were asymptomatic or silent AF; however, in 86.5% of the patient population, remote monitoring indicated the need for therapy change. The results of the study showed a high incidence of AF among the patient population (18.7%), with an average follow up of 252 days. According to this study, remote monitoring is an effective tool for earlier detection and treatment of atrial fibrillation.

Significant Interactions With The Most Commonly Used Herbal And Non-herbal Supplements Impact Warfarin Safety And Efficacy

According this observational study, eight out of the top ten supplements commonly taken by American consumers, such as garlic, ginkgo and essential fatty acids, have been reported to impact the effectiveness of warfarin and overall safety of the individual. The study analysed the top 20 herbal and 20 non-herbal supplements taken by Americans, based on 2008 sales data. Researchers examined supplement and drug interactions with reported changes in international normalised ratio (INR), bleeding, and thromboembolic events. The findings reveal that of the top ten most commonly used herbal and non-herbal supplements—glucosamine, chondroitin, co-enzyme Q10, multi-herbs, probiotic, antioxidants, melatonin, cranberry and soy—more than 90 percent have been reported to interact negatively with warfarin. Of the 40 most commonly taken supplements, 35% were associated with a significant change in INR, 64% increased the risk of bleeding and 36 % decreased the effectiveness of warfarin.

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