An analysis of long-term data from the MADIT II (Multicenter automatic defibrillator trial II) clinical study demonstrates that the life-saving benefits of implantable cardioverter defibrillator (ICD) therapy remain sustainable at eight years.
This is the first time long-term data have been presented regarding the life-saving benefits of ICDs in a primary prevention population. The analysis was presented during a late-breaking session at Heart Rhythm 2009, the Heart Rhythm Society’s 30th annual Scientific Sessions (13-16 May, Boston, US).
The analysis shows a sustainable mortality benefit over time, including:
• At eight years, one life is saved for every six patients who receive an ICD. This represents a significant improvement over the two-year MADIT II data, which showed one life saved for every 17 patients;
• A 41% relative reduction in the risk of death for ICD patients at four years;
• A 37% relative reduction in the risk of death for ICD patients at eight years.
“The results of the extended follow-up of the MADIT-II trial provide hope for long-term survival among patients suffering from life-threatening heart conditions that can often times lead to sudden cardiac death, a leading killer in this country and abroad,” said lead author Ilan Goldenberg, Heart Research Follow-up Program at the University of Rochester Medical Center in Rochester, New York, US, who presented the data at Heart Rhythm 2009. “This study proves that ICD therapy, sustained for over eight years, does in fact improve survival rates and ultimately save lives.”
The MADIT-II trial enrolled 1,232 patients with ischaemic left ventricular dysfunction and follow-up was conducted through November 2001. For the current long-term efficacy study, researchers acquired post-trial mortality data for all study patients from the US and European National Death Registries. Modeling was carried out to determine the long-term outcomes of patients with an implantable defibrillator versus patients not treated with a device.
After a cumulative follow-up period of eight years, results of the MADIT-II trial reveal an all-cause mortality probability of 45% among patients with an ICD as compared to 61% among patients without a device. The 16% increase corresponds to 1.2 life-years saved with an ICD during an eight-year period.
While ICD therapy was shown to result in significant survival benefits in the first four years of follow-up, analysis proves that ICD therapy was associated with additional life-saving benefits during the extended four to eight years of follow-up, proving the overall survival benefit from an ICD was sustained over an eight year period. The study also found that long-term device efficacy was enhanced among patients who received a limited amount of right ventricular pacing from the ICD and among those who did not develop heart failure progression during the study.
The MADIT II study, sponsored by Boston Scientific, was designed to determine whether ICDs improve survival when compared to drug therapy alone in heart attack survivors with moderate impairment of the left ventricle. Initial results published in the New England Journal of Medicine (March 21, 2002) demonstrated that ICD therapy reduced the relative risk of death by 31% at 20 months follow-up.
“ICD therapy has proved effective in patients at risk of sudden cardiac death, and now the long-term MADIT II data show the life-saving benefits of these devices continue over time,” said Arthur J Moss, Professor of Medicine at the University of Rochester Medical Center and principal investigator of the MADIT, MADIT II and MADIT-CRT trials.