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Am Fam Physician. 2010;81(1):68

Background: Hemodynamically unstable patients with acute pulmonary embolism (PE) are candidates for thrombolytic therapy because they are at higher risk of morbidity and mortality. However, patients with impending right ventricular failure may not receive thrombolysis because they initially appear to be stable. These patients often have elevated troponin levels, but it is unclear whether this measurement could be used to identify patients at risk of becoming hemodynamically unstable.

The Study: Jiménez and colleagues conducted a meta-analysis of studies that measured cardiac troponin levels in normotensive patients with acute symptomatic PE. All studies used a cutoff point of no more than 0.5 ng per mL (0.5 mcg per L) to identify an elevated troponin level.

Results: Nine studies were reviewed and involved 1,366 patients with PE. There were 377 patients (27.6 percent) with elevated troponin levels, 15.9 percent of whom died, compared with 3.4 percent of patients with normal troponin levels. However, the rate of elevated troponin levels was only marginally greater in persons who died compared with those who survived (positive likelihood ratio = 2.26), whereas the rate of nonelevated troponin levels was slightly lower in persons who died compared with those who survived (negative likelihood ratio = 0.59).

Conclusion: An elevated troponin level alone should not determine whether thrombolytic therapy should be administered to patients with acute PE. Troponin levels are most useful when used in addition to evidence of right ventricular strain on echocardiography or computed tomography in conjunction with clinical prognostic scores.

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