Table 2

Unadjusted Factors Associated With the Occurrence of ICD Shocks

VariableHR95% CIp Value
Age ≥60 yrs0.980.93–1.030.44
Female0.910.65–1.260.56
Nonwhite race1.361.02–1.820.036
Previous MI1.050.81–1.370.70
LVEF per 5% increase1.030.93–1.130.58
Beck score ≥81.010.99–1.020.45
CCS angina class
 II–IV vs. none1.250.81–1.940.68
 I vs. none1.180.73–1.89
Diabetes0.830.62–1.120.22
COPD0.930.60–1.450.76
Smoking status
 Previous vs. never1.140.84–1.550.42
 Current vs. never1.300.87–1.94
Systolic BP per 10 mm Hg increase0.920.85–0.990.03
Diastolic BP per 10 mm Hg increase0.600.42–0.870.006
Resting HR per 5 beats/min increase1.030.96–1.100.40
Body mass index per 1-U increase1.010.98–1.030.60
Duration of CPX per 1-min increase0.960.93–1.000.044
Peak Vo2 per 1 ml/kg/min increase0.980.95–1.010.21
VeVCo2 slope per 5-U increase1.421.05–1.920.022
Training heart rate per 5 beats/min increase0.970.93–1.020.23
Exercise-induced dysrhythmia1.691.25–2.280.001
Previous AF/AFL1.471.11–1.940.007
Previous sustained VT/VF1.781.36–2.320.001
Biventricular pacing0.930.71–1.220.60
Beta-blocker0.670.42–1.090.11
Digoxin1.361.04–1.780.024
ACE inhibitor/ARB1.280.72–2.300.40
Statin0.870.67–1.140.31
Aldosterone antagonism1.080.83–1.410.57
Loop diuretic1.230.76–1.990.40
Aspirin1.130.85–1.490.40
Antiarrhythmic therapy1.190.89–1.600.24

BP = blood pressure; CCS = Canadian Cardiovascular Society; CI = confidence interval; HR = hazard ratio; PVC = premature ventricular contraction; VeVCo2 = ventilation (VE) and carbon dioxide output (VCo2) slope; other abbreviations are as in Table 1.

  • Exercise-induced dysrhythmia was defined in the HF-ACTION cardiopulmonary exercise test protocol as any exercise test complicated by serious arrhythmia (supraventricular tachycardia, sustained ventricular tachycardia, or fibrillation ≥7 PVCs/min, ventricular bigeminy or trigeminy, or nonsustained ventricular tachycardia (≥3 beats).