Đáng chú ý là các số tử vong đột ngột trong thử nghiệm HẠN thấp (17 trường hợp tử vong đột ngột, 14 trong nhóm điều khiển so với ba trong nhóm với ICD) và do đó, mặc dù ý nghĩa thống kê, kết quả là không thống kê mạnh mẽ. | Heart failure 171 were reduced by the ICD but the overall mortality of 7 per year was lower than anticipated and the trend for reduction in mortality did not reach statistical significance 54 . Notably the number of sudden deaths in the DEFINITE trial was low 17 sudden deaths 14 in the control group versus three in the group with ICDs and therefore although statistically significant the result is not statistically robust. Based on the presented but yet unpublished data of the SCD-HeFT trial 48 of the 2521 patients enrolled had nonischemic cardiomyopathy. Subgroup analysis suggests similar benefit for ischemic and nonischemic cardiomyopathy. Appreciation of the magnitude of benefit and limitiations of ICDs are important considerations in the use of ICDs in heart failure populations. In advanced heart failure the risk of death from pump failure and options for ventricular assist devices cardiac transplantation and potential for benefit from cardiac resynchronization therapy are important considerations. Although patients with severe class IV heart failure are at high risk for sudden death benefit from an ICD is limited by deaths from pump failure and an ICD is not appropriate therapy for many. Patients with class IV symptoms have been excluded from all ICD trials. Those patients who are candidates for cardiac transplantation however may receive substantial benefit despite severe heart failure if an ICD prevents sudden death while they are on an out-patient list awaiting transplantation 3 4 . Although the risk of ICD implantation is low occasional patients with advanced heart failure experience deterioration in heart failure following the implantation procedure. In addition it is important to consider the potential adverse impact that can occur when implantation of an ICD results in right ventricular pacing with consequent change in ventricular activation similar to that of left bundle branch block. This effect likely contributed to the excess mortality observed with
