Clinical Research
Cardiac Rhythm Disorder
Factors Influencing Appropriate Firing of the Implanted Defibrillator for Ventricular Tachycardia/Fibrillation: Findings From the Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II)

https://doi.org/10.1016/j.jacc.2005.05.088Get rights and content
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Objectives

The purpose of this study was to prospectively examine the role of clinical, laboratory, echocardiographic, and electrophysiological variables as predictors of appropriate initial implantable cardioverter-defibrillator (ICD) therapy for ventricular tachycardia (VT) or ventricular fibrillation (VF) or death in the Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II) population.

Background

There is limited information regarding the determinants of appropriate ICD therapy in patients with reduced ventricular function after a myocardial infarction.

Methods

We used secondary analysis in one arm of a multicenter randomized clinical trial in patients with a previous myocardial infarction and reduced left ventricular function.

Results

We analyzed baseline and follow-up data on 719 patients enrolled in the ICD arm of the MADIT-II study. Appropriate ICD therapy was observed in 169 subjects. Clinical, laboratory, echocardiographic, and electrophysiological variables, along with measures of clinical instability such as interim hospitalization for congestive heart failure (IH-CHF) and interim hospitalization for coronary events (IH-CE), were examined with proportional hazards models and Kaplan-Meier time-to-event curves before and after first interim hospitalization. Interim hospitalization-CHF, IH-CE, no beta-blockers, digitalis use, blood urea nitrogen (BUN) >25, body mass index (BMI) ≥30 kg/m2, and New York Heart Association functional class >II were associated with increased risk for appropriate ICD therapy for VT, VF, or death. In a multivariate (stepwise selection) analysis, IH-CHF was associated with an increased risk for the end point of either VT or VF (hazard ratio [HR] 2.52, 95% confidence interval [CI] 1.69 to 3.74, p < 0.001) and for the combined end point of VT, VF, or death (HR 2.97, 95% CI 2.15 to 4.09, p < 0.001). Interim hospitalization-CE was associated with an increased risk for VT, VF, or death (HR 1.66, 95% CI 1.09 to 2.52, p = 0.02).

Conclusions

These results provide important mechanistic information, suggesting that worsening clinical condition and cardiac instability, as reflected by an IH-CHF or IH-CE, are subsequently associated with a significant increase in the risk for appropriate ICD therapy (for VT/VF) and death.

Abbreviations and Acronyms

BMI
body mass index
BUN
blood urea nitrogen
CE
coronary events
CHF
congestive heart failure
CI
confidence interval
HR
hazard ratio
ICD
implantable cardioverter-defibrillator
IH
interim hospitalization
LVEF
left ventricular ejection fraction
MADIT-II
Multicenter Automatic Defibrillator Implantation Trial II
MI
myocardial infarction
NYHA
New York Heart Association
VF
ventricular fibrillation
VT
ventricular tachycardia

Cited by (0)

Drs. Moss and Hall are Guidant research grant recipients. Dr. Ruskin has been a consultant/advisor to Medtronic. Dr. Singh has been a consultant/advisor to Guidant Corporation.