Background: Implantable cardioverter defibrillator (ICD) therapy has recently been expanded for the prevention of sudden cardiac death based on the results of SCD-HeFT trial. We assessed the hypothesis that combination of Holter-based risk predictors may identify low-risk postinfarction patients with LV dysfunction unlikely to benefit from ICD therapy.
Methods: Heart rate turbulence after ventricular and atrial premature beats, short-term scaling exponent alfa, mean deceleration magnitude, and prevalent low-frequency oscillation of heart rate were calculated from 24-h Holter recordings in patients with LVEF<=35% in the population of EMIAT and ATRAMI trials. Composite risk predictor based on combination of risk factors, which were individually dichotomized to achieve high negative predictive value for cardiac events, was defined in EMIAT and validated in ATRAMI population. Cox proportional hazard survival analysis was performed for both populations with mean follow-up of 22 months.
Results: Total 143 / 444 (32.2%) and 71 / 177 (40.1%) patients belonged to low-risk group in EMIAT and ATRAMI trial, respectively. In low-risk group, only 5 cardiac (2 arrhythmic, 3 non arrhythmic) deaths were observed in EMIAT and 2 events (1 nonfatal cardiac arrest, 1 non-arrhythmic death) were observed in ATRAMI.
|
|
low-risk group |
rest of population |
hazard ratio for low-risk group |
log rank p |
|
EMIAT (n=444) |
5 / 143 (3.3%) |
58 / 301 (19.3%) |
0.16 |
0.0001 |
|
ATRAMI (n=177) |
2 / 71 (2.8%) |
16 / 106 (15.1%) |
0.18 |
0.02 |
Conclusion: Holter-based risk stratification can identify significant proportion of postinfarction patients with LV dysfunction who are at very low risk (< 1% / year) of preventable death.
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