Reyes de Torres Chacon, MD
Several biomarkers are being tested to help us point to which patients with cryptogenic stroke are most likely to have hidden atrial fibrillation as the real etiology of the stroke. Some of these biomarkers are echocardiography-based as left atrial enlargement, others are rhythm-based such as a high number of atrial premature beats or atrial runs, and others are laboratory-based as heart failure indicators like Nt-ProBNP, D-Dímer, or antithrombin-III. All these indicators could point out which patient we should continue to perform additional tests for the detection of atrial fibrillation.
In this study, it was shown that the blood values of NT-ProBNP ≥505 pg/ml have a high sensitivity (93%) and specificity (72%) to detect heart-related causes of stroke, mainly atrial fibrillation. Even in patients with cryptogenic stroke, high levels of NT-ProBNP were associated with detection of hidden AF at follow up (levels below 505 pg/ml had a negative predictive value of 98%). Other blood biomarkers related to myocardial damage and hypercoagulability, such as D-dimer or antithrombin-III, also show an association with AF-related stroke, but with lower sensitivity and specificity (D-dimer cutoff value of 0.70 μg/ml, sensitivity of 61%, and specificity of 58%; 89% decrease in AT-III value has a sensitivity of 53% and specificity of 69%).
The authors point to the fact that during the study follow up, they detected 14 new cases of new-onset atrial fibrillation with extended cardiac monitoring; 85% of them had NT-proBNP values higher than 505 pg/ml (sensitivity, 86%; specificity, 65%).
Although these blood biomarkers are not specific to atrial fibrillation and may be elevated in other conditions such as myocardial damage, heart failure, prothrombotic states and renal failure, they can be used in daily practice to decide which patients with cryptogenic stroke could benefit from extended cardiac monitoring and other specific tests to detect hidden atrial fibrillation. In combination with other cardiac biomarkers, they could help us make the most cost-effective diagnostic approach to the patient with cryptogenic stroke, due to the multiple aetiologies behind this concept.
