Troponin elevation in the setting of acute pulmonary embolism (PE) is of small magnitude and short duration and can go unnoticed in pts referred late after symptom onset. Prospective, single-center registry of pts with confirmed intermediate-risk PE, defined as at least 1 echocardiographic finding of right ventricular (RV) dysfunction (endo-diastolic (EDRV)/left ventricular (EDLV) end-diastolic diameter ratio >=1 in the 4-chamber view, paradoxical septal systolic motion or pulmonary hypertension defined as RV/atrial gradient >30mmHg), or positive troponin test. Combined in-hospital endpoint was defined as death, non-fatal recurrent PE, or residual pulmonary vascular obstruction (RPVO) ≥35%. 282 pts were included, age 66±14 years, 59% women, 174 (62%) referred ≤5 days after symptom onset, 108 (38%) after >5 days. Troponin elevation was observed in 126 (72%) treated within ≤5 days, in 60 (56%) treated after >5 days (p=0.004). A significant interaction was observed between time since symptom onset and both troponin elevation and persistence of EDRV/EDLV diameter ratio>1 at 48h. The negative predictive value of troponin elevation was 85% in patients treated within 5 days of symptoms, but fell to 70% in those admitted >5 days after symptom onset (p=0.002). Positive troponin was an independent predictor of adverse outcome (OR=1.43 [1.08-5.56]). ROC curves show that prognostic value of positive troponin test was higher in pts referred ≤5 days than in pts referred >5 days after symptom onset (p=0.01). There is a significant relation between troponin elevation and time since symptom onset in patients with intermediate-risk PE. Negative predictive value of troponin elevation is adequate in pts treated early (≤5 days) but is suboptimal in pts treated >5 days after symptom onset. Table Results <=5 days since symptom onset >5 days since symptom onset p Sensitivity 72% (61.3-82.7) 51% (42.4-59.6) 0.005 Specificity 42% (44.5-49.5) 47% (39.1-54.9) 0.33 PPV 26% (18.4-33.6) 30% (22.2-37.8) 0.81 NPV 85% (78.4-91.6) 70% (63-77) 0.002