Short answer: No — BNP (or NT-proBNP) does not directly measure myocardial or device-related fibrosis. It reflects cardiac wall stress and hemodynamic load. If fibrosis leads to ventricular dysfunction or elevated filling pressures, BNP may rise indirectly, but it is not a specific fibrosis biomarker.
Why BNP is not a fibrosis marker
- BNP/NT-proBNP are secreted in response to myocardial stretch and elevated intracardiac pressures; they are validated for heart-failure diagnosis and risk stratification, not for quantifying fibrosis.
- Levels are influenced by many factors (age, renal function, BMI, rhythm, acute/chronic loading conditions), limiting specificity for tissue changes like fibrosis.
What actually measures myocardial fibrosis?
- Cardiac MRI: Late gadolinium enhancement (LGE), native T1 mapping and extracellular volume (ECV) quantify focal and diffuse fibrosis.
- Serum biomarkers of collagen turnover: Pro- and telopeptides of type I/III collagen (e.g., PINP, PICP, PIIINP), and remodeling/inflammation markers (galectin-3, sST2) are more mechanistically linked to fibrotic processes than BNP, though none are perfectly specific.
- Echocardiography with strain: Global longitudinal strain and mechanical dyssynchrony track functional impact that may accompany fibrosis.
Leadless pacemakers and “local” fibrosis
Leadless pacemakers (e.g., RV Micra/Aveir) typically become locally encapsulated by fibrous tissue at the device–endocardial interface over months to years. This is a localized reaction and is not expected to produce a reliable systemic BNP signal. BNP could increase only if broader ventricular function or filling pressures worsen for other reasons.
Clinical interpretation
- Use BNP/NT-proBNP to evaluate hemodynamic stress/heart failure, not to quantify fibrosis caused by a pacemaker.
- To answer a fibrosis question, prefer CMR (T1/ECV/LGE) and, if needed, collagen-turnover biomarkers (PINP/PICP/PIIINP, galectin-3, sST2).
- If symptoms change after a leadless pacemaker implant, assess pacing site, percentage, timing, RV function, tricuspid valve status, and consider imaging for remodeling/fibrosis.
Key references
- Heidenreich PA, et al. 2022 AHA/ACC/HFSA Guideline: natriuretic peptides for HF diagnosis/risk. Circulation.
- Doyle RS, et al. Cardiac MRI T1/ECV for fibrosis detection (systematic review). Diagnostics 2025.
- Breeman KTN, et al. Tissues attached to retrieved leadless pacemakers show fibrous encapsulation. Heart Rhythm 2021.
- Ding Y, et al. Biomarkers of myocardial fibrosis (collagen peptides, gal-3, sST2). Frontiers 2020.
- Tsutsui H, et al. Natriuretic peptides in diagnosis/prognosis of HF. J Card Fail 2023.