analytical evaluation and comparison of dupont aca lactate dehydrogenase1 ld1 isoenzyme assay diagnostic efficiency for acute myocardial infarction detection with other ld1 methods and aca ckmb a twosite study the purpose of this study was to examine the analytical characteristics of a rapid new assay for lactate dehydrogenase 1 ld1 isoenzyme on the dupont aca analyzer and the diagnostic efficiency of ld1 for detection of acute myocardial infarction ami when used alone and with creatine kinase mb ckmb total aca ld1 assay precision with percent coefficients of variation cvs of less than 32 from 56 ul to 469 ul ld1 across fifty assay days was excellent linearity was confirmed from 0 to 332 ul and no detectable calibration drift was noted from 5 to 489 ul over a ninetyday period the aca ld1 results compared well with roche isomuneld1 abbott spectrum agent helena electrophoresis and beckman electrophoresis ld1 methods giving rs from 0987 to 0994 slopes from 094 to 165 and yintercepts from 295 to 694 ul examination of 450 ambulatory subjects about equally distributed by sex yielded a 43 14 ul aca ld1 patient reference interval serum samples from 159 consecutive patients at the university of tennessee memorial hospital and 96 patients at allentown hospital submitted for ami detection assistance were assayed in a singleblind study for ld1 and ionexchange ckmb by dupont aca methods which provide automated results in ten minutes whenever needed the aca ld1 assay yielded a clinical sensitivity of 89 and specificity of 95 for ami with a decision threshold of 120 ul the diagnostic efficiency of the aca ld1 assay was 94 at 120 ul which equaled or exceeded that of the three comparative ld1 methods the predictive value of positive pv and negative pv results on the first sample collected were 80 and 85 for aca ld1 65 and 90 for aca ionexchange ckmb and 83 and 90 when both tests were combined significantly the pv and pv results when two or more samples were assayed was improved to 88 and 95 for aca ld1 relatively constant at 65 and 97 for aca ionexchange ckmb and dramatically improved to 95 and 100 when both ckmb and ld1 tests were combined the results from these two medical centers show that the aca ld1 assay provides useful clinical information for ami diagnosis when employed alone or in combination with aca ckmb these results also suggest that ld1 should be included in biochemical evaluations for ami to attain optimal predictive values of results