At what point should ST elevation be measured?

Junior doctors are failing to recognise ST elevation, and there are wide variations in practice, suggests UK research. Given that junior doctors usually decide who should be given thrombolytic therapy, the finding is of some concern, and perhaps the time has come for a consensus to be reached, conclude the authors.

A sample of 63 junior doctors in emergency and general medicine from three large teaching hospitals in Manchester, England, took part in the study. Each doctor was shown three ECG complexes and asked to identify and quantify the degree of ST elevation, and to mark the points at which they had measured it.

ST elevation was missed completely in 12% of cases, and a wide variety of points along the ST segment were used to assess elevation, resulting in wide discrepancies. More than four out of 10 doctors measured more than 3 mm of ST elevation in ECG 1. Six doctors used the T wave. In ECG 3, almost half the doctors measured more than 2 mm of ST elevation; only eight measured it at the J point (1.6 mm or more).

Experienced clinicians are likely to rely on pattern recognition rather than absolute measurement of the ST segment, gleaning additional clues from other information on the ECG, such as reciprocal changes in other leads or Q waves, and the altered shape of the ST segment. But junior doctors are unlikely to have the benefit of this experience, and won't find any clues in many clinical textbooks and published thrombolysis trials.