URG-L: Fw: DINAMIT study: ICD immediately after MI of no benefit

[Alain Vadeboncoeur]

http://www.theheart.org/ Mar 8, 2004 DINAMIT study: ICD immediately after MI of no benefit New Orleans, LA - Patients who have just had an AMI and are at high risk of arrhythmic death should not receive an implantable cardiac defibrillator (ICD), findings from a new trial reported here today indicate. Dr Stefan Hohnloser Presenting the results of the Defibrillator in AMI (DINAMIT) study at a late-breaking session, Dr Stefan Hohnloser (JW Goethe-University College, Frankfurt, Germany) said: "Although ICDs prevent arrhythmic death, there was an unexpected increase in nonarrhythmic death in the patients who received a defibrillator. These results suggest that you have to wait before everything is stabilized before you implant an ICD." "In fact, in the MADIT trial, the average time between MI and implantation of the ICD was 1.5 years," Hohnloser noted. The DINAMIT findings are in direct contrast with those of another study in the late-breaking sessions todaythe Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) results. The latter was conducted in a different patient population, howeverthose with moderate to severe heart failure. In SCD-HeFT, ICD therapy lowered the risk of sudden death by 23% compared with placebo. First randomized study to assess impact of ICD very early after MI Dr Stuart Connelly (McMaster University, Hamilton, ON), who was also involved in the study, explained that post-MI mortality remains very high, and 40% of these deaths are arrhythmic in nature. "DINAMIT is the first randomized controlled trial to assess the impact of ICD therapy very early after MI," he noted. Patients were randomized to optimal medical therapy plus an ICD (n=332) or optimal medical therapy alone (control; n=342) within 40 days of MI. The majority of patients were receiving optimal drug therapy, with >80% on beta blockers, around 90% taking ACE inhibitors, 75% receiving statins, and 80% to 90% taking antiplatelet agents. The bradycardia-pacing rate for those with an ICD was set to 40 to 45 beats per minute. The primary end point of the study was all-cause mortality; secondary end points included arrhythmic death and quality of life. The study began in 1998 and ended in September 2002; maximum follow-up was four years but average follow-up was 2.5 years. Does the ICD therefore change the mode of death from arrhythmic to nonarrhythmic? There was no difference between the two groups in the primary end point, all-cause mortality. There was a highly significant, greater-than-50% reduction in arrhythmic death in the patients who received an ICD, "but this was offset by the increase in nonarrhythmic deaths in these patients," Hohnloser said. "Does the ICD therefore change the mode of death from arrhythmic to nonarrhythmic?" he wondered. The nonarrhythmic deaths were primarily cardiovascular in nature and included heart failure and MI, he said, adding, "We are looking at this subject in greater detail." DINAMIT: Mortality outcomes Mortality outcome ICD deaths (n) ICD incidence of deaths/year (%) Control deaths (n) Control incidence of deaths/year (%) Hazard ratio p All-cause mortality 62 7.5 58 6.9 1.08 0.66 Arrhythmic death 12 1.5 29 3.5 0.42 0.0094 Nonarrhythmic death 50 6.1 29 3.5 1.75 0.016 Our study defines a limit to ICD therapy. In conclusion, Hohnloser said: "ICDs did not significantly reduce the rate of mortality in these high-risk patients immediately after MI, and our study defines a limit to ICD therapy." He said he did not know what other therapy to suggest for these early post-MI patients at high risk of arrhythmic death, noting that two major trials of amiodarone in this patient population had shown no benefit of that antiarrhythmic drug. Related links 1. ICD guidelines to change next week 2. Inconclusive results regarding the benefit of ICD implantation in post-MI patients taking beta-blockers 3. ICD meta-analysis: Risk stratification remains the challenge 4. MADIT II: mortality reduction with ICD implantation for patients with prior MI, LV dysfunction