What is the best course of treatment for an adult patient with thrombocythemia (elevated platelet count), experiencing upper back pain and intermittent chest pain, with potential cardiovascular risk factors?

Management of Thrombocythemia with Upper Back Pain and Intermittent Chest Pain

This patient requires immediate cardiovascular evaluation to rule out acute coronary syndrome (ACS), followed by risk-stratified treatment of essential thrombocythemia with low-dose aspirin and potentially cytoreductive therapy based on thrombotic risk factors.

Immediate Assessment for Acute Coronary Syndrome

The combination of chest pain and thrombocythemia demands urgent exclusion of ACS, as elevated platelet counts significantly increase thrombotic risk 1, 2, 3:

• Obtain 12-lead ECG immediately to assess for ST-segment changes, T-wave abnormalities, or other ischemic patterns 4
• Measure high-sensitivity cardiac troponins at presentation and repeat at 6-12 hours if initial values are normal 4
• Assess hemodynamic stability, including blood pressure, heart rate, and signs of heart failure (pulmonary rales, peripheral edema) 4
• Calculate GRACE score for risk stratification if ACS is suspected 4

Critical caveat: Thrombocythemia patients presenting with chest pain have a 11% risk of arterial thrombosis and may develop microthrombotic occlusions not detectable by standard coronary angiography 3, 4. The chest pain may represent microvascular ischemia from platelet-mediated thrombosis rather than epicardial coronary disease 5, 6.

Risk Stratification for Essential Thrombocythemia

Once ACS is excluded or managed, classify the patient's thrombotic risk 1, 2:

High-Risk Criteria (requires cytoreductive therapy):

• Age >60 years with JAK2 mutation, OR
• Prior thrombosis at any age 1, 2, 3

Intermediate-Risk Criteria:

• Age >60 years without JAK2 mutation and no prior thrombosis 1

Low-Risk Criteria:

• Age ≤60 years with JAK2 mutation but no prior thrombosis 1, 2

Very Low-Risk Criteria:

• Age ≤60 years, JAK2 wild-type, no prior thrombosis 1

Treatment Algorithm

For All Risk Categories:

Screen for acquired von Willebrand syndrome before initiating aspirin if platelet count >1,500 × 10⁹/L to prevent bleeding complications 2, 7. This is a critical step often overlooked.

High-Risk Patients (Most Likely Category Given Symptoms):

Initiate dual therapy immediately 1, 2, 8:

1. Low-dose aspirin 81-100 mg daily - This addresses the microvascular symptoms (chest pain, back pain) that are characteristic of thrombocythemia 1, 2, 3, 5

   • In one case report, atypical chest pain from essential thrombocythemia responded dramatically to aspirin with complete symptom resolution 5
   • Aspirin reduces arterial thrombosis risk from 9.4/1000 patient-years in untreated patients 3

2. Hydroxyurea as first-line cytoreductive therapy 1, 2, 8

   • Target platelet count <600,000/mm³ 8
   • In a randomized trial of 114 high-risk patients, hydroxyurea reduced thrombotic events from 24% to 3.6% (P=0.003) 8, 3
   • Alternative agents if hydroxyurea is not tolerated: interferon-alpha or anagrelide 7, 6

Intermediate-Risk Patients:

• Low-dose aspirin 81-100 mg daily 1
• Consider cytoreductive therapy based on additional cardiovascular risk factors (hypertension, diabetes, smoking, hyperlipidemia) 1, 3
• JAK2 mutation status influences decision: JAK2-positive patients have 4-fold increased venous thrombosis risk 3

Low-Risk Patients:

• Low-dose aspirin 81-100 mg daily for microvascular symptoms 1, 2
• Manage cardiovascular risk factors aggressively 1, 7

Very Low-Risk Patients:

• Observation without cytoreductive therapy may be appropriate 1
• Consider aspirin if symptomatic 2

Management of Concurrent ACS (If Present)

If ACS is confirmed, thrombocytopenia from treatment creates unique challenges 4:

• Aspirin improves 7-day survival without increasing bleeding risk even in cancer patients with thrombocytopenia 4
• Dual antiplatelet therapy (aspirin + P2Y12 inhibitor) can be used if platelet count >30,000/μL 4
• Single-agent aspirin if platelet count 10,000-30,000/μL 4
• Reduced heparin doses (30-50 units/kg) if platelet count <50,000/μL 4
• Percutaneous coronary intervention should not be denied due to thrombocytopenia if clinically indicated 4

Monitoring Requirements

• Regular complete blood counts to assess platelet response and monitor for disease progression 1, 2
• Bone marrow aspirate and biopsy before initiating cytoreductive therapy to rule out myelofibrosis 1
• Surveillance for transformation to myelofibrosis (10% at 8.5 years) or acute myeloid leukemia (3% at 10 years) 3, 6

Critical Pitfalls to Avoid

• Do not delay aspirin therapy while awaiting genetic testing results if symptoms suggest microvascular ischemia 5, 6
• Do not use therapeutic phlebotomy in essential thrombocythemia (this is for polycythemia vera only) 1
• Do not withhold life-saving interventions for ACS due to concerns about thrombocytopenia 4
• Do not start aspirin without screening for von Willebrand syndrome if platelet count >1,500 × 10⁹/L 2

The chest and back pain in this patient likely represents microvascular ischemia from platelet-mediated thrombosis, which typically responds dramatically to low-dose aspirin within days 5, 6. However, ruling out ACS remains the immediate priority before attributing symptoms solely to thrombocythemia.