Abstract 1999: Excellent Negative Predictive Value for the Combination of Low D-Dimer Level, Normal Ejection Fraction and Sinus Rhythm for Predicting Absence of Intracardiac Spontaneous Contrast and Thrombus: A Prospective Transesophageal Echocardiographic Study
Background : Although transesophageal echocardiogram (TEE) is a front line test for assessment of cardioembolic sources of thrombi, clinicians are uncertain if all patients need TEE and if a subgroup is present where TEE may be deferred. D-dimer (DD) is a well established blood test to reflect activation of the coagulation system but its role in intracardiac thrombotic diagnosis has not been evaluated.
Rationale: To determine the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of DD for intracardiac thrombus (ICT) and intracardiac spontaneous contrast (ICSC) and to see if DD in combination with known predictors of lower thrombotic risk (normal EF, sinus rhythm) may be a good predictor of no ICT/ICSC.
Methods: Consecutive patients presenting with stroke or TIA, atrial fibrillation and atrial flutter who were referred for TEE were evaluated prospectively. All confounders for elevation of DD served as exclusion criteria. Clinical, TEE variables and DD level (ELISA assay) were determined. Patients were grouped according to DD level (< 500 or ≥ 500) and EF (<50% or ≥ 50%).
Results: 103 patients were included (75 stroke/TIA and 28 atrial fibrillation/flutter). There were 4 patients with left atrial thrombus and 16 patients with atrial spontaneous contrast (ASC). No patient had ventricular thrombi or spontaneous contrast. Patients in the thrombus/ASC arm had significantly lower EF (35% versus 50%, P<0.001) and higher rates of atrial fibrillation/flutter (75% versus 21%, p<0.001). Using the pre-specified DD cutoffs, a sens of 50%, spec of 56%, PPV of 21.3% and NPV of 82.5% for ICT/ICSC were achieved. However the combination DD <500 and EF ≥ 50% had NPV of 95.2%. The combination of EF ≥ 50% and the presence of sinus rhythm yielded NPV of 98.3%. Adding the three variables together (EF ≥ 50%, sinus rhythm and DD <500) yielded NPV of 100%.
Conclusion: The combination of low DD (<500), normal EF and sinus rhythm has a NPV of 100% for ICT/ICSC and may identify patients in whom TEE may not be needed. Since the combination of normal EF (which can be determined by transthoracic echo) and sinus rhythm has excellent NPV ( 98.3%), whether additional routine DD estimation adds cost effectiveness needs prospective validation.