Circulation 2000 Jan 25;101(3):244-51
Severity of coronary artery calcification by electron beam computed
tomography predicts silent myocardial ischemia.
He ZX, Hedrick TD, Pratt CM, Verani MS, Aquino V, Roberts R, Mahmarian JJ.
BACKGROUND: Detection of subclinical coronary artery disease (CAD) before the
development of life-threatening cardiac complications has great potential
clinical relevance. Electron beam computed tomography (EBCT) is currently the
only noninvasive test that can detect CAD in all stages of its development and
thus has the potential to be an excellent screening technique for identifying
asymptomatic subjects with underlying myocardial ischemia. METHODS AND RESULTS:
Over 2.5 years, we prospectively studied 3895 generally asymptomatic subjects
with EBCT, 411 of whom had stress myocardial perfusion tomography (SPECT) within
a close (median, 17 days) time period. SPECT and exercise treadmill results were
compared with the coronary artery calcium score (CACS) as assessed by EBCT. The
total CACS identified a population at high risk for having myocardial ischemia
by SPECT although only a minority of subjects (22%) with an abnormal EBCT had an
abnormal SPECT. No subject with CACS <10 had an abnormal SPECT compared with
2.6% of those with scores from 11 to 100, 11.3% of those with scores from 101 to
399, and 46% of those with scores >/=400 (P<0.0001). CACS predicted an
abnormal SPECT regardless of subject age or sex. CONCLUSIONS: CACS identifies a
high-risk group of asymptomatic subjects who have clinically important silent
myocardial ischemia. Our results support the role of EBCT as the initial
screening tool for identifying individuals at various stages of CAD development
for whom therapeutic decision making may differ considerably.
