Relative effectiveness of the implantable cardioverter-defibrillator and antiarrhythmic drugs in patients with varying degrees of left ventricular dysfunction who have survived malignant ventricular arrhythmias

OBJECTIVES We sought to assess the effect of baseline ejection fraction on survival difference between patients with life-threatening ventricular arrh ythmias who were treated with an antiarrhythmic drug (AAD) or implantable c ardioverter-defibrillator (ICD). BACKGROUND The Antiarrhythmics Versus Implantable Defibrillators (AVID) stu dy demonstrated improved survival in patients with ventricular fibrillation or ventricular tachycardia with a left ventricular ejection fraction (LVEF ) less than or equal to 0.40 or hemodynamic compromise, METHODS Survival differences between AAD-treated and ICD-treated patients e ntered into the AVID study (patients presenting with sustained ventricular arrhythmia associated with an LVEF less than or equal to 0.40 or hemodynami c compromise) were compared at different levels of ejection fraction. RESULTS In patients with an LVEF greater than or equal to 0.35, there was n o difference in survival between AAD-treated and ICD-treated patients. A te st for interaction was not significant, but had low power to detect an inte raction. For patients with an LVEF 0.20 to 0.34, there was a significantly improved survival with ICD as compared with AAD therapy. In the smaller sub group with an LVEF <0.20, the same magnitude of survival difference was see n as that in the 0.20 to 0.34 LVEF subgroup, but the difference did not rea ch statistical significance. CONCLUSIONS These data suggest that patients with relatively well-preserved LVEF (greater than or equal to 0.35) may not have better survival when tre ated with the ICD as compared with AADs. At a lower LVEF, the ICD appears t o offer improved survival as compared with AADs, Prospective studies with l arger patient numbers are needed to assess the effect of relatively well-pr eserved ejection fraction (greater than or equal to 0.35) on the relative t reatment effect of AADs and the ICDs. (J Am Coll Cardiol 1999;34:1090-5) (C ) 1999 by the American College of Cardiology.