Prognostic Importance of Exercise Brain Natriuretic Peptide in Asymptomatic Chronic Organic Severe Mitral Regurgitation: An Observational Study
Bibliographic record
Abstract
Background: The optimal timing of surgery in patients with chronic organic severe mitral regurgitation (MR) continues to be debated, especially for those who are asymptomatic. The aim of the study was to determine independent and additive prognostic value of exercise brain natriuretic peptide (eBNP) in patients with severe asymptomatic MR and normal left ventricular ejection fraction (LVEF). Methods: Two hundred twenty-three consecutive patients with severe MR defined by effective regurgitant orifice (ERO) area ? 40 mm 2 and/or residual volume >= 60 mL, LVEF > 60%, and normal LV end-systolic diameter < 40 mm underwent symptom limited exercise treadmill test (TMT). Echocardiography was done immediately after exercise. Data were obtained within 3 minutes of peak exercise. BNP levels were assessed before echo (after 30 minutes of supine rest) and at exercise (i.e., within the 3 minutes of the end of effort). Patients were followed up every 3 months up to 15 months for major adverse cardiac events (MACEs) (cardiovascular death, need for mitral valve surgery and hospitalization for acute pulmonary edema or heart failure). Results: Mean age was 31.2 ± 9 years (range: 18 - 40) with majority being male (n = 153; 68%). Etiologies were rheumatic (n = 201; 90%), mitral valve prolapse (n = 17; 7.6%) and hypertrophic cardiomyopathy (n = 5; 2.4%). BNP level significantly increased from rest (65.24 ± 43.92 pg/mL; median: 43.5 pg/mL) to exercise (100.24 ± 98.24 pg/mL; median: 66.5 pg/mL; P < 0.001). Patients were divided into three tertiles according to eBNP levels (T 1 = 15 - 44; T 2 = 45 - 104; T 3 = 105 - 400). There was trend for significantly lower exercise time in T 3 . During TMT, 66 (29.5%) stopped exercise due to dyspnea. They had similar resting BNP level compared with others but had significantly higher eBNP level (136 ± 109.7 pg/mL vs. 84.88 ± 90.2 pg/mL; P < 0.001). During follow-up (15 months), MACE occurred in 83 patients (37.2%): mitral valve replacement (MVR) in 59 patients (symptomatic: 43; LV dilatation or dysfunction: 9; both symptoms and dilatation/dysfunction: 7), 17 hospitalizations for congestive heart failure, five patients developing acute pulmonary edema and atrial fibrillation in remaining two patients. This was 7.6%, 35% and 69% in T 1 , T 2 and T 3 , respectively and had significantly higher eBNP level than without any event (165 ± 119 pg/mL vs. 57 ± 48 pg/mL; P < 0.001). Using receiver operating characteristic curve analysis, the best cut-off value of eBNP level to predict cardiac events was 90 pg/mL (sensitivity: 75%; specificity: 88.6%; positive predictive value: 79%; negative predictive value: 83.9%). Conclusion: In asymptomatic patients, eBNP level provides incremental prognostic value beyond echocardiographic data and those with elevated eBNP should be considered at high risk for reduced event-free survival and might be considered for early MVR. J Clin Med Res. 2016;8(11):797-804 doi: http://dx.doi.org/10.14740/jocmr2680w
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".