|
medpundit |
||
 |
 |
|
Friday, October 24, 2003Doctors believe the test would be used first in emergency rooms to distinguish people who are genuinely on the brink of a cardiac emergency from millions more who have chest pain from other causes. Eventually, it may be offered in doctors' offices as part of a battery of blood tests capable of identifying those who have heart disease but don't know it. The test could save thousands of lives.... ..."You can tell a patient he did great (on a conventional test), and a week later he drops dead," says Eric Topol of the Cleveland Clinic, an author of the study in today's New England Journal of Medicine. "There's always been something missing." The new test measures blood levels of an enzyme called myeloperoxidase, which plays a key role in the body’s response to inflammation of various types. The study of 604 consecutive emergency room patients complaining of chest pains showed that those with the highest levels of MPO face a fourfold increased risk of a cardiac crisis within two months. The study does show a trend for greater risk of heart disease as levels of myeloperoxidase increase: Myeloperoxidase levels were higher in patients who had a myocardial infarction within 16 hours after presentation than in those who did not (median, 320 vs. 178 pM; P<0.001). Among patients who had no biochemical evidence of clinically significant myocardial necrosis at presentation, base-line myeloperoxidase levels were significantly elevated in those who had elevated cardiac troponin T levels (0.1 ng per milliliter) within the ensuing 4 to 16 hours, but not in those who were consistently negative for troponin T (median, 353 vs. 309 pM; P<0.001). The incidence of myocardial infarction increased with increasing quartiles of myeloperoxidase levels: it was 13.9 percent in quartile 1 (less than 119.4 pM), 16.6 percent in quartile 2 (119.4 to 197.9 pM), 25.2 percent in quartile 3 (198.0 to 393.9 pM), and 38.4 percent in quartile 4 (394.0 pM or more) (P<0.001 for trend). Patients who were initially negative for troponin T who subsequently had measurable levels at 4 to 16 hours were more likely to be in the third or fourth myeloperoxidase quartile than in the first or second quartile (proportion with 0.1 ng per milliliter troponin T levels, 5.3 percent of those in both quartile 1 and quartile 2, 8.0 percent of those in quartile 3, and 17.2 percent of those in quartile 4; P<0.001 for trend). Myeloperoxidase levels also correlated with the frequency of an adjudicated diagnosis of an acute coronary syndrome, increasing from 22.5 percent in quartile 1 to 58.0 percent in quartile 4 (P<0.001 for trend). Base-line myeloperoxidase levels were higher among patients who subsequently required revascularization or had a major adverse cardiac event (myocardial infarction, reinfarction, need for revascularization, or death) in the ensuing 30-day and 6-month periods than in those who did not have such complications (P<0.001 for all comparisons). Myeloperoxidase levels were also higher among the 34 patients who died within six months after presentation than among the 570 patients who did not die (median, 270 vs. 194 pM; P=0.05). However, as an accompanying editorial points out, the test isn’t ready for prime time: The sensitivity, specificity, and predictive value of this measure, however, were only moderate. So, don’t expect to go to your doctor and have this test ordered. It has yet to prove itself useful. posted by Sydney on 10/24/2003 08:54:00 AM 0 comments 0 Comments: |
|
