Correlation of the location of coronary arterial spasm with the lead distribution of ST segment elevation during variant angina

The lead distribution of ST segment elevation produced by severe “spasm” of major coronary arteries was correlated with the specific artery involved in a group of 110 cases of variant angina with single vessel coronary arterial spasm made up from eight cases personally observed and 102 cases abstracted from published literature.The most sensitive and specific lead for ST elevation during anterior descending (LAD) coronary arterial spasm was V₃; V₂ was almost as good. For spasm of either the right (RCA) or circumflex coronary artery (CMFX), Leads 3 and aV_F showed ST elevation most frequently; electrocardiographically it was difficult to distinguish between spasm of these two vessels. ST elevation in Leads V₅ and V₆ was not specific, occurring in some cases of spasm of each of the three major coronary arteries. ST elevation in Lead V₁ occurred in either RCA or LAD spas, but never in CMFX spasm. ST elevation in Lead 1 was never seen with isolated RCA spasm.No single lead can detect all cases of transient ST elevation. Simultaneous monitoring of Leads 3 and V₃ would have detected 98.2% of 333 cases of ST elevation reviewed, and addition of Lead aV_L would have detected most of the remainder. These findings should be considered in lead selection for monitoring to detect ST elevation, and in using the ECG to identify spastic coronary arteries.