In a 68‑year‑old with stable hypertrophic cardiomyopathy and known atherosclerosis, what is the role of B‑type natriuretic peptide (BNP) or N‑terminal pro‑B‑type natriuretic peptide (NT‑proBNP) and high‑sensitivity cardiac troponin T (hs‑cTnT) for risk stratification?

Role of BNP/NT-proBNP and hs-cTnT in Risk Stratification for Hypertrophic Cardiomyopathy

In a 68-year-old with stable HCM and atherosclerosis, both BNP/NT-proBNP and high-sensitivity cardiac troponin T should be measured routinely for risk stratification, as they provide independent and complementary prognostic information about heart failure progression, cardiovascular events, and mortality risk. 1, 2

BNP/NT-proBNP: Marker of Ventricular Wall Stress and Heart Failure Risk

What These Biomarkers Reflect

• Natriuretic peptides are elevated in HCM due to ventricular wall stress from pressure/volume overload, not necessarily acute decompensation. 3
• In HCM, ventricular myocytes re-express fetal genes including BNP in response to cardiac stress, shifting production from primarily atrial to predominantly ventricular release. 3
• These peptides serve as quantitative markers related to the extent of left ventricular dysfunction and filling pressures, making them objective measures of disease severity. 3

Prognostic Value in HCM

• Plasma BNP levels ≥200 pg/mL identify HCM patients at significantly increased risk for cardiovascular events including HCM-related death, heart failure hospitalization, embolic stroke, and ventricular arrhythmias. 2
• NT-proBNP correlates with established disease markers including left ventricular thickness, symptom status, and left ventricular hemodynamics by Doppler measurements. 1
• Natriuretic peptides predict clinical risk in HCM independently of established risk factors, and their prognostic power is additive when combined with troponin. 1, 2

Clinical Application

• Use natriuretic peptides to provide an objective measure of therapy efficacy by monitoring changes in filling pressures and response to treatment. 1
• Serial measurements are more valuable than single values—a reduction in BNP/NT-proBNP levels indicates good treatment response and favorable prognosis, while persistent elevation suggests inadequate therapy. 3
• In your 68-year-old patient, elevated natriuretic peptides would signal increased ventricular wall stress and higher risk of heart failure progression, warranting closer monitoring and potential therapy intensification. 1

High-Sensitivity Cardiac Troponin T: Marker of Ongoing Myocardial Injury

What This Biomarker Reflects

• Troponin elevation in HCM reflects ongoing myocyte injury or necrosis, not acute coronary syndrome, and must be interpreted in the clinical context of cardiomyopathy rather than ischemia. 3
• In HCM, troponin elevation indicates continuous myocardial damage from microvascular ischemia, increased wall stress, and myocardial disarray. 1

Prognostic Value in HCM

• Elevated hs-cTnI (≥0.04 ng/mL) identifies HCM patients with significantly more frequent cardiovascular events compared to those with low troponin values. 2
• Positive hs-TnI testing is associated with higher calculated 5-year sudden cardiac death risk according to ESC risk calculators, independent of other risk factors. 4
• Serum cTnI is an independent predictor of myocardial fibrosis detected by late gadolinium enhancement on cardiac MRI, with cTnI ≥0.025 ng/mL showing 88% sensitivity for detecting fibrosis. 5
• The extent of myocardial fibrosis correlates positively with troponin levels (r = 0.371, P <0.001), making troponin a surrogate marker for structural disease severity. 5

Clinical Application

• In your 68-year-old patient with known atherosclerosis, an elevated troponin must be interpreted as ongoing myocardial injury from HCM pathophysiology, not acute coronary syndrome, unless clinical presentation suggests otherwise. 3
• hs-cTnT shows the strongest association with focal myocardial fibrosis extent (b = 0.20, R² = 0.28), making it particularly useful for identifying patients with advanced structural disease. 6

Combined Biomarker Strategy: Superior Risk Stratification

Complementary Information

• NT-proBNP is the stronger predictor for diastolic dysfunction (E/E′ association: b = 0.06, R² = 0.28), while hs-cTnT is more strongly associated with myocardial fibrosis extent. 6
• These biomarkers reflect different pathophysiologic pathways—NT-proBNP indicates hemodynamic stress while troponin indicates myocyte injury—providing distinct but complementary prognostic information. 3, 1

Additive Prognostic Value

• Patients with both elevated cTnI (≥0.04 ng/mL) AND elevated BNP (≥200 pg/mL) have an 11.7-fold increased risk of cardiovascular events compared to those with both biomarkers in the normal range. 2
• Combined measurements of these biomarkers significantly improve risk stratification beyond either marker alone. 2

Practical Algorithm for Your Patient

For a 68-year-old with stable HCM and atherosclerosis:

1. Measure both NT-proBNP and hs-cTnT at baseline to establish risk profile. 1, 2

2. Interpret results using these thresholds:

   • NT-proBNP: Use age-adjusted cutoff >1800 pg/mL for patients >75 years, or >900 pg/mL for ages 50-75 years 7
   • hs-cTnT: Use ≥6 ng/L as elevated 7
   • cTnI: Use ≥0.04 ng/mL as high risk 2

3. Risk stratify based on combined results:

   • Both biomarkers normal: Lower risk, standard monitoring
   • Either biomarker elevated: Intermediate risk, closer follow-up
   • Both biomarkers elevated: Highest risk (11.7-fold increase), requires aggressive management and frequent monitoring 2

4. Repeat measurements every 6-12 months to assess disease progression and treatment response. 1

5. If troponin is elevated, consider cardiac MRI to quantify myocardial fibrosis, as cTnI ≥0.025 ng/mL combined with maximum wall thickness ≥21 mm has 95% specificity for detecting fibrosis. 5

Important Caveats

Factors Affecting Interpretation

• Obesity significantly reduces natriuretic peptide levels through increased clearance and suppression of pro-BNP synthesis, potentially masking underlying cardiac dysfunction despite significant disease. 7, 3
• Atrial fibrillation increases BNP and NT-proBNP concentrations even without heart failure, requiring higher diagnostic cutoff values in this population. 3
• Renal dysfunction elevates NT-proBNP independent of cardiac function, with severe renal failure producing extremely high levels. 3
• In your patient with atherosclerosis, ensure troponin elevation is not from acute coronary syndrome by correlating with clinical presentation, ECG changes, and serial measurements. 3

Medication Effects

• ACE inhibitors, ARBs, beta-blockers, and spironolactone reduce natriuretic peptide levels through reduction in filling pressures. 3
• If your patient is on sacubitril/valsartan (ARNI), only use NT-proBNP for monitoring, NOT BNP, as ARNI increases BNP levels because BNP is a substrate for neprilysin. 3