Heart Rhythm 2007 Late Breaking Clinical Trials I Abstracts FOR IMMEDIATE RELEASE
Contact: Ann-Marie White
Heart Rhythm Society
202-464-3476
awhite@hrsonline.org
DENVER — The following Late Breaking Clinical Trials Abstracts were presented on Thursday, May 10 from 10:30 a.m. – 12:00 p.m., Wells Fargo Theatre 1, Denver Convention Center as a part of HeartRhythm 2007:
10:30 a.m. — “T-wave Alternans Predicts Mortality in a Population Undergoing a Clinically Indicated Exercise Test”
Background: As a part of the Finnish Cardiovascular Study, researchers tested the hypothesis that T-wave alternans (TWA) predict mortality in patients referred for a clinical exercise test.
Methods: 1037 patients with a clinically indicated exercise test and with a technically successful ECG data during a bicycle ergometer test were included in the study. Digital ECGs were recorded and TWA was analyzed continuously with the time-domain modified moving average (MMA) method. The maximum TWA value at heart rate (HR) was derived and its capacity to stratify risk for all-cause, cardiovascular and sudden cardiac death was tested.
Results: During a follow up of about 44 months, 59 patients died of either cardiovascular disease or sudden cardiac arrest. In multivariate analysis after adjusting for age, sex, previous myocardial infarction and other factors, the relative risk of TWA was 7.4 for sudden cardiac death, 6.0 for cardiovascular mortality, and 3.3 for all-cause mortality 3.3.
Conclusions: Time-domain TWA analysis powerfully predicts mortality in a general population undergoing a clinical exercise test.
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10:45 a.m.— “Cardiac Arrhythmias and Risk Stratification in Patients with Low Ejection Fraction after Acute Myocardial Infarction: The CARISMA Study”
Pending: Abstract not yet posted.
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11:00 a.m.— “Improved Stratification of Autonomic Regulation for Risk Prediction (ISAR Risk) in Post-Infarction Patients with Preserved Left Ventricular Function”
Background: Most deaths after myocardial infarction (MI) are in patients with preserved left ventricular ejection fraction (LVEF greater than 30%) in whom risk prediction is challenging. Heart rate turbulence (HRT) and Deceleration Capacity (DC) are new, powerful risk factors linked to baroreflex and autonomic modulations. This cohort study investigated the potential of using HRT and DC to predict follow-up deaths in post-MI patients with LVEF greater than 30 percent.
Methods:Acute MI survivors aged more than 76 years and in sinus rhythm were enrolled. HRT and DC values were obtained from 24h Holter records. Patients with both HRT category 2 (HRT 2) and DC ≤ 4.5 ms were prospectively classified as high risk. Primary and secondary endpoints were all-cause, cardiac and sudden cardiac mortality.
Results: The study enrolled 2,376 patients with acute revascularization in 2,292 cases. Among these patients, 185 died during a 5-year follow-up. Of these deaths, 42 were in 127 pts with LVEF ≤ 30% and 143 in 2,249 pts with LVEF > 30%. In patients with LVEF > 30%, combination of HRT 2 and DC ≤ 4.5 identified another high risk group of similar size and prognosis. Multivariate regression analysis showed significant hazard ratios of 3.4 and 3.0 for HRT 2 and DC ≤ 4.5 ms, respectively. ROC analysis confirmed that HRT and DC were superior to all other tested risk markers.
Conclusion: In post-MI patients with preserved LVEF and abnormal autonomic markers, mortality rate is equivalent to that in patients with depressed LVEF. Prophylactic implantable cardioverter-defibrillator trials are feasible in these patients providing HRT and DC are used to identify the high risk group.
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11:15 a.m.— “Ventricular Tachycardia Ablation in addition to Implantable Defibrillators in Coronary Heart Disease (VTACH): A Prospective Randomized Multicenter Study”
Methods: In a prospective randomized study, 110 patients were included with a history of myocardial infarction, reduced left ventricular function and hemodynamic stable VT. Patients were randomized to either VT ablation plus ICD implantation (ABL+ICD) or ICD implantation alone (ICD only). The primary endpoint was the time to the first VT recurrence. Secondary endpoints were evaluated for the number of VT events per year, for electrical VT storm and for death. Follow up was completed for 2 years in 16 European centers. Data were analyzed for statistics by an independent institute.
Results: Data were obtained from 50 patients randomized to ABL+ICD and 55 patients to ICD only. Another five patients dropped out because they withdrew their consent. Clinical data were well balanced for both groups. No major complications due to VT ablation occurred. During a follow up of 2 years, any form of VT event was seen in 33 (66%) ABL+ICD vs. 38 (72%) ICD only patients. The median time from ICD implant to the first VT episode was 9.1 months for ABL+ICD vs. 5.4 months for the ICD only patients. The mean number of VT events per year was 9.2 VT for ABL+ICD patients vs. 19.6 VT for the ICD only patients. The total number of VT episodes was 640 for ABL+VT patients vs. 1421 for ICD only patients. VT storm occurred in 10 ABL+ICD patients vs. 15 ICD only patients. The mortality was not different in both groups (4 vs. 3 deaths). The mean number of appropriate ICD therapies per patient and year of follow up was 12.8 in the ABL+ICD group vs. 26.8 in the ICD only group. The calculated median for the number of ICD therapies per patient and year was 0.7 for ABL+ICD vs. 3.7 for ICD only treated patients.
Conclusions: In patients with stable VT and prior myocardial infarction, VT ablation reduces recurrences by 50% without reaching significance.
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11:30 a.m.— “Aggressively Programmed Implantable Defibrillator Detection and Therapy Reduces Shocks Compared to Physician-tailored Programming in Primary Prevention Patients: Results from the PREPARE Trial”
Methods: PREPARE was a prospective, non-randomized study which included analysis of 658 patients with primary prevention indications for an ICD from 38 centers. Parameters were set to detect rhythms with a rate greater than 182 bpm (beats per minute) with duration of at least 30 of 40 ventricular beats. ATP before maximum output shock was programmed for rhythms with a regular cycle length and a rate between 182 and 250 bpm. SVT discriminators were used for rhythms with rates up to 200 bpm. The control cohort consisted of 689 primary prevention patients from the EMPIRIC and MIRACLE ICD trials for whom VT/VF detection and therapy programming was not controlled. The PREPARE patients had longer VF detection duration, more ATP use and faster treatment cut-offs when compared to the control cohort.
Results: The primary objective of reducing the Morbidity Index in the study population compared to control was met. The Morbidity Index incidence density was 0.18 events/patient-year for the PREPARE cohort versus 0.69 events/patient-year for the control cohort in the first year of follow up. Poisson regression analysis confirmed that PREPARE pts had a significantly lower Morbidity Index incidence density than control pts when differences in baseline characteristics were considered. PREPARE patients were less likely to receive a shock in the first year as compared to control. Arrhythmic syncope rates were low in both groups.
Conclusions: The incidence of untreated VT and arrhythmic syncope was similar between PREPARE and the control cohort. PREPARE programming significantly reduced shocks when compared to the control cohort as measured by the Morbidity Index and the rate of shocked episodes at 1 year.
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11:45 a.m.— “Dual Chamber and VVI Implantable Defibrillator (DAVID) II Trial Results”
Methods: In DAVID II, 600 patients who met DAVID enrollment criteria each received a dual chamber ICD, and were randomized to atrial pacing at 70 bpm or standby right ventricular pacing at 40 bpm. All patients had comparable target criteria for CHF medications during the trial. Quarterly follow up assessed clinical status, medication use, ICD events and quality of life parameters. CHF hospitalizations were adjudicated using strict objective criteria by an events committee who were blinded to treatment assignment. At enrollment, there were no significant differences in demographic or clinical characteristics between treatment groups, 85% of whom were men and 93% had ischemic heart disease. Patients averaged 63 years of age with a mean LVEF of 26.5% ± 7.6. At baseline, 44% of patients had New York Heart Association Class I CHF, 47% had class II, and 10% class III CHF. Mean follow up was 28 ± 9 months.
Results: Study findings, including the combined endpoint of death or CHF hospitalization, treatment complications, and arrhythmia events between treatment groups, were presented and their implications discussed.
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About the Heart Rhythm Society
The Heart Rhythm Society is the international leader in science, education and advocacy for cardiac arrhythmia professionals and patients, and the primary information resource on heart rhythm disorders. Its mission is to improve the care of patients by promoting research, education and optimal health care policies and standards. Incorporated in 1979 and based in Washington, DC, it has a membership of over 4,000 heart rhythm professionals in more than 60 countries around the world.
