In an 80‑year‑old woman with chest pain and cardiac catheterization showing non‑occlusive coronary artery disease, modestly elevated high‑sensitivity troponin (hs‑troponin), markedly elevated N‑terminal pro‑brain natriuretic peptide (NT‑proBNP), anemia, low albumin, hyponatremia, intermittent hypokalemia, elevated inflammatory markers (CRP, ESR), supratherapeutic international normalized ratio (INR), and a limited transthoracic echocardiogram revealing preserved ejection fraction, what additional diagnostic tests and medication regimen should be initiated?

Management of 80-Year-Old Woman with Chest Pain, Non-Occlusive CAD, and Elevated Biomarkers

This patient requires urgent investigation for the cause of her persistent troponin elevation (rising from 44 to 80 ng/L) and markedly elevated NT-proBNP (2,351 pg/mL) despite non-obstructive coronary disease, with immediate focus on identifying non-ACS causes of myocardial injury—particularly given her severe anemia (hemoglobin 8.9-10.4 g/dL), inflammatory state (CRP 270 mg/L), and reduced ejection fraction (55-61%).

Critical Diagnostic Priorities

Immediate Additional Testing Required

1. Cardiac Imaging to Define Myocardial Pathology

• Cardiac MRI with gadolinium contrast is the definitive test to distinguish between:
  • Myocarditis/myopericarditis (given elevated inflammatory markers)
  • Stress cardiomyopathy (Takotsubo)
  • Infiltrative disease (given low albumin, anemia)
  • Microvascular dysfunction
  • Small vessel disease not visible on angiography 1

The echocardiogram shows borderline reduced EF (55-61%) with elevated NT-proBNP, suggesting either diastolic dysfunction or ongoing myocardial stress that requires tissue characterization 2.

2. Anemia Workup (Critical Priority)

• Iron studies, B12, folate, reticulocyte count
• Peripheral smear review
• Stool guaiac/FIT testing (given supratherapeutic INR suggests anticoagulation)
• Consider GI evaluation if iron deficiency confirmed

The normocytic anemia (MCV 83-85) with elevated inflammatory markers could represent:

• Anemia of chronic disease
• Occult bleeding (especially with INR 3.3)
• Bone marrow suppression
• Hemolysis (check LDH, haptoglobin)

Anemia alone can cause troponin elevation through supply-demand mismatch 2, 3, and correcting hemoglobin may resolve cardiac biomarker abnormalities.

3. Inflammatory/Infectious Source Investigation

• Blood cultures (already drawn, pending)
• Echocardiogram with focus on valves to exclude endocarditis
• Chest CT (CTA already done) review for infiltrates, masses
• Autoimmune serology if no infectious source: ANA, RF, complement levels
• Thyroid function tests (hypothyroidism can elevate troponin) 2

The persistent leukocytosis (10.7-13.0), neutrophilia, elevated CRP (270 → 22.7 mg/L), and ESR (63 → 52 mm/hr) suggest ongoing inflammation despite negative respiratory viral panel and cultures.

4. Electrolyte Repletion and Monitoring

• Aggressive potassium and magnesium replacement (K+ dropped to 2.6 mEq/L)
• Daily electrolytes until stable
• ECG monitoring for arrhythmias (QTc prolonged at 469-521 ms)

Hypokalemia with prolonged QTc increases risk of ventricular arrhythmias, which could explain chest pain and troponin elevation.

5. Renal Function Assessment

• Urinalysis with microscopy (already done, trace blood)
• Urine protein-to-creatinine ratio
• Consider renal ultrasound if proteinuria present

Troponin can be chronically elevated with renal dysfunction (eGFR 61-89 mL/min/1.73m²), though this is borderline 2, 3.

Tests NOT Immediately Needed

• Repeat coronary angiography: Already performed, showed non-obstructive disease
• Stress testing: Contraindicated with elevated troponin and ongoing symptoms 3
• Additional troponin measurements: Pattern already established (persistently elevated 44→80 ng/L)
• CK-MB or myoglobin: No added value with contemporary troponin assays 4

Medication Management

Continue/Optimize Current Therapy

1. Antiplatelet Therapy

• Aspirin 75-150 mg daily (if not already on) 5
• Consider clopidogrel 75 mg daily for dual antiplatelet therapy given elevated troponin, though non-obstructive CAD makes benefit less clear 5

2. Beta-Blocker

• Continue or initiate (e.g., metoprolol 25-50 mg BID, titrate to HR 60-70)
• Reduces myocardial oxygen demand
• Indicated for ACS and heart failure 5

3. Statin Therapy

• High-intensity statin (atorvastatin 40-80 mg or rosuvastatin 20-40 mg daily)
• Indicated for CAD regardless of obstruction severity 4

4. ACE Inhibitor or ARB

• Initiate low-dose (e.g., lisinopril 2.5-5 mg daily)
• Indicated for reduced EF (55-61% is borderline) and elevated NT-proBNP
• Provides mortality benefit in heart failure 4

5. Diuretic Therapy

• Consider low-dose loop diuretic (furosemide 20-40 mg daily) if volume overload present
• NT-proBNP of 2,351 pg/mL suggests elevated filling pressures

6. Anticoagulation Management

• Hold warfarin temporarily with INR 3.3 (supratherapeutic)
• Recheck INR daily until therapeutic (2.0-3.0)
• Investigate indication: Atrial fibrillation? Venous thromboembolism? (ECGs show sinus rhythm, but paroxysmal AFib possible)
• Consider switching to DOAC if indication is AFib (easier management, less bleeding risk)

7. Anemia Treatment

• Iron supplementation if deficient (oral ferrous sulfate 325 mg TID or IV iron if severe/intolerant)
• Consider transfusion if hemoglobin <7-8 g/dL with ongoing ischemia
• Erythropoiesis-stimulating agents only if renal failure and iron-replete

8. Electrolyte Replacement

• Potassium chloride 40-80 mEq daily (divided doses) to maintain K+ >4.0 mEq/L
• Magnesium oxide 400 mg BID to maintain Mg >2.0 mg/dL

Medications to AVOID

• Nitrates: May be used for symptom relief but do not improve mortality 4
• Calcium channel blockers: Second-line if beta-blocker contraindicated 5
• GP IIb/IIIa inhibitors: Not indicated without obstructive CAD and planned PCI 3
• Thrombolytics: Absolutely contraindicated (no STEMI, supratherapeutic INR) 5

Risk Stratification and Prognosis

This patient is HIGH RISK based on:

• Elevated troponin (80 ng/L, well above 99th percentile ~14 ng/L for hs-cTnT) 2, 3, 4
• Markedly elevated NT-proBNP (2,351 pg/mL) predicts mortality independent of troponin 6, 7
• Borderline reduced EF (55-61%)
• Severe anemia (hemoglobin 8.9-10.4 g/dL)
• Inflammatory state (CRP 270 mg/L)
• Advanced age (80 years)
• Multiple comorbidities (hypoalbuminemia, hyponatremia, renal insufficiency)

The combination of elevated troponin and NT-proBNP confers 2-5 fold increased mortality risk 6, 7, even with non-obstructive CAD 8, 9.

Diagnostic Algorithm Summary

1. Cardiac MRI → Define myocardial pathology (myocarditis, infiltration, microvascular disease)
2. Anemia workup → Iron studies, B12/folate, smear, GI evaluation if indicated
3. Inflammatory source → Review cultures, consider autoimmune workup, TEE if endocarditis suspected
4. Electrolyte correction → Aggressive K+/Mg replacement, daily monitoring
5. Optimize medical therapy → Aspirin, beta-blocker, statin, ACE-I, diuretic as needed
6. Anticoagulation adjustment → Hold warfarin, recheck INR, clarify indication

Critical Pitfalls to Avoid

1. Assuming troponin elevation = ACS: With non-obstructive CAD, consider alternative causes—anemia, myocarditis, stress cardiomyopathy, renal dysfunction, sepsis 2, 3, 10.

2. Ignoring anemia: Hemoglobin 8.9 g/dL can cause supply-demand mismatch and troponin elevation independent of coronary disease 2.

3. Over-anticoagulation: INR 3.3 increases bleeding risk, especially with anemia. Clarify indication and adjust dosing.

4. Hypokalemia with prolonged QTc: Potassium 2.6 mEq/L with QTc 511 ms is dangerous—aggressive replacement mandatory.

5. Missing inflammatory/infectious etiology: Persistent leukocytosis and CRP 270 mg/L require explanation. Endocarditis, myocarditis, or systemic inflammatory disease must be excluded.

6. Premature stress testing: Contraindicated with elevated troponin and ongoing symptoms 3.

7. Underestimating NT-proBNP significance: Level of 2,351 pg/mL predicts high mortality and suggests heart failure, even with preserved EF 9, 11, 6, 7.

5, 2, 3, 4, 1, 8, 9, 6, 7