Tachycardia: low ejection fraction, female gender and conventional therapy increase the risk of a shock from an implanted defibrillator.

Clinical bottom line (level 2b)

Patients who have survived an out-of-hospital ventricular fibrillation are at increased risk of a shock being given by an implanted defibrillator within 2 years if they: have a low ejection fraction, are female or have been given conventional therapy.

Dolack : American Journal of Cardiology 1994; 73: 237-241

Expires October 2004

The study

Prospective cohort study with objective outcomes, adjusted for confounding factors, not validated in an independent set of patients.

Setting: in the community, USA

88 patients (aged mean 64 years, 90% male) survivors of an out-of-hospital ventricular fibrillation enrolled in defibrillator study

Excluded if

VF associated with an acute Q wave myocardial infarction

Factors studied:

defibrillator shock given

Patients were randomised to receive either amiodarone or conventional treatment, and an implantable cardioverter-defibrillator was placed.

Cox regression analysis was used to adjust for confounding factors.

100% followed for 2 years
Outcomes studied:

defibrillator shock given

The evidence

outcome	time to outcome	number of patients/total number	% (95% CI)
defibrillator shock given	2 years	40/88	45.5% (35.1% to 55.9%)

Low ejection fraction: shock given p= 0.002
Female gender: shock given p= 0.007
Conventional drug therapy: shock given p= 0.015

Comments

No odds ratios were given for this trial.

Citation

Dolack GL, : Clinical predictors of implantable cardioverter-defibrillator shocks (results of the CASCADE trial). American Journal of Cardiology 1994; 73: 237-241

Contributor: Clare Wotton and Bob Phillips, October 1999
Reviewer:

_{Clinical Question.}

_Patient	_{survivors of out-of-hospital ventricular fibrillation}
_{Intervention or Exposure}	_{risk factors}
_Comparison	_{no risk factors}
_Outcome	_{implantable cardioverter-defibrillator shocks}