Silent ST segment deviations and extent of coronary artery disease.

Fifty patients who underwent coronary and left ventricular angiography for suspected coronary artery disease (CAD) had ambulatory ECG monitoring at a time remote from that of catheterization. After correcting for positional ST segment variation on ambulatory ECG, the amount of time that ST segments deviated more than 1 mm. from baseline without corresponding angina was determined, and these results were correlated with results of angiography. Silent ST segment deviations were seen in patients without significant CAD in 2.2% of observations, but increased significantly with extent of coronary artery disease (2.9%, 8.2%, and 10.1% of observations in the one-, two-, and three-vessel disease groups, respectively). This relationship was independent of ventricular function, resting ECG, and previous symptoms. It is concluded that silent ST segment deviations on ambulatory ECG reflect the presence and severity of coronary artery disease.