COMPARISON OF THE DIAGNOSTIC-ACCURACY OF DIFFERENT METHODS OF MEASUREMENT OF HEART RATE-ADJUSTED ST-SEGMENT DEPRESSION DURING EXERCISE TESTING FOR IDENTIFICATION OF CORONARY-ARTERY DISEASE

Within a population of 160 consecutive symptomatic patients who all ha d undergone catheterization (80 with greater than or equal to 1 stenos is greater than or equal to 50%), we compared the accuracy of differen t computerized measurements of the exercise-induced changes in ST-segm ent: (1) the standard criterion (greater than or equal to 0.1 mV flat/ downsloping ST depression or greater than or equal to 0.15 mV upslopin g depression, both 60 ms after the J point); (2) heart rate (HR)-adjus ted ST-segment depression (ST/HR index measured at 0 20, 40, 60, and 8 0 ms from the J point); (3) the HR-adjusted ST integral (ST/HR integra l measured from 0 to 40 ms and from 40 to 80 ms after the J point). No ne of the ST/HR indexes or integrals were found to have a significantl y greater sensitivity than the standard criterion. On the contrary, al l ST/HR indexes and integrals showed a higher specificity (0.78 to 0.8 9) than did the standard criterion (0.65); moreover, the earlier the m easurement within the repolarization phase, the better the overall acc uracy: 0.71 for the standard criterion, 0.83 (p<0.001), 0.80 (p<0.01), 0.78 (p<0.02), 0.78 (p<0.02), 0.74 (p = NS) for the ST/HR indexes at 0, 20, 40, 60, and 80 ms, respectively; 0.81 (p<0.001) and 0.78 (p<0.0 2) for the ST/HR integrals calculated from 0 to 40 and from 40 to 80 m s, respectively. Consistently, the receiver-operating characteristic c urve areas of ST/HR at 0, 20, and 40 ms were greater than those of ST/ HR at both 60 and 80 ms. These findings are divergent from some other results given in published reports. We conclude that the accuracy of a ll exercise criteria is influenced by the population analyzed: our pat ients were representative of those currently seen by clinicians.