Demonstration of exercise-induced painless myocardial ischemia in survivors of out-of-hospital ventricular fibrillation

To ascertain if myocardial ischemia is the mechanism of out-of-hospital ventricular fibrillation (VF), left ventricular (LV) function was assessed at rest and during submaximal exercise in 15 patients who survived out-of-hospital VF. They were separated into asymptomatic (9 patients, group A) and symptomatic (6 patients, group S) groups for a history of angina or myocardial Infarction. Both groups had significant (at least 70% diameter stenosis) coronary artery disease. At catheterization no patient had angina during exercise, but 12 of 15 had ST depression or Increased ST depression (group A, 1.9 ± 1.4 mm; group S, 1.1 ± 1.2 mm) and 11 had abnormal wall motion. From rest to exercise, patients in group S had increased LV end-diastolic pressure (from 21 ± 9 to 37 ± 11 mm Hg, p = 0.0092) and volume (from 100 ± 25 to 107 ± 26 ml/m², p = 0.006), with no significant change in LV ejection fraction (from 40 ± 13 to 42 ± 12%). In group A LV end-diastolic pressure increased from 19 ± 4 to 31 ± 8 mm Hg (p = 0.001), but neither end-diastolic volume nor ejection fraction changed significantly (from 83 ± 13 to 92 ± 23 ml/m² and from 55 ± 13% to 46 ± 13%, respectively). Thus, patients with coronary artery disease who survive out-of-hospital VF may have evidence of myocardial ischemia during exercise without pain. Painless ischemia may have a role In out-of-hospital VF.