What is the differential diagnosis for asymptomatic bilateral lower leg 'modeling' in a patient with very mild heart failure with preserved ejection fraction, who is maintained on topiramate (5 mg) for epilepsy or migraines?

Differential Diagnosis for Asymptomatic Bilateral Lower Leg Mottling in HFpEF

The most likely diagnosis is chronic venous insufficiency, which is a common noncardiac mimic of heart failure congestion and should be distinguished from true cardiac edema, especially when the findings are asymptomatic, bilateral, stable for months, and present in a patient with well-controlled mild HFpEF. 1

Primary Differential Considerations

Noncardiac Mimics (Most Likely)

Chronic venous insufficiency is the leading consideration for asymptomatic bilateral lower leg changes that have been stable for months in a patient with otherwise well-controlled heart failure. 1 The 2023 ACC Expert Consensus specifically identifies chronic venous insufficiency as a primary noncardiac entity that can cause lower extremity findings mimicking cardiac congestion. 1

Key distinguishing features to assess:

• Venous stasis changes: Look for hemosiderin deposition (brownish discoloration), varicose veins, skin thickening, or lipodermatosclerosis 1
• Absence of pitting edema: Chronic venous changes often present with skin changes without significant edema, particularly when asymptomatic 1
• Stability over months: True cardiac congestion from HFpEF would typically fluctuate with volume status and respond to diuretic therapy 1

Other Noncardiac Causes

Liver disease can cause lower extremity findings and should be considered, though this typically presents with more systemic signs. 1 Evaluate for:

• Hepatomegaly, ascites, or other stigmata of chronic liver disease 1
• Liver function tests and albumin levels 1

Renal dysfunction may contribute to bilateral lower extremity changes, though your patient's stable clinical course on low-dose diuretics argues against progressive kidney disease as the primary cause. 1

Cardiac-Related Considerations (Less Likely Given Clinical Context)

Decompensated HFpEF is unlikely given that the patient is described as having "very mild" heart failure with adequate symptom control on minimal diuretic therapy (topiramate appears to be a transcription error for a diuretic, likely torsemide 5 mg). 1, 2 True cardiac congestion would typically present with:

• Pitting edema that worsens throughout the day 1
• Associated symptoms (dyspnea, orthopnea, weight gain) 1
• Elevated jugular venous pressure 1
• Response to diuretic adjustment 1

Clinical Approach to Distinguish Causes

The 2023 ACC guidelines emphasize that not all bilateral lower extremity findings in HFpEF patients represent cardiac congestion. 1 Apply this stepwise assessment:

1. Assess for true volume overload: Check for jugular venous distension, orthopnea, paroxysmal nocturnal dyspnea, weight gain, or pulmonary rales 1

2. Examine the quality of lower extremity changes:

   • Pitting edema that improves with leg elevation suggests cardiac or renal causes 1
   • Non-pitting changes with skin discoloration suggest chronic venous insufficiency 1
   • Mottling (livedo reticularis pattern) may indicate vascular or rheumatologic conditions 1

3. Consider the temporal pattern: Stable findings over many months without symptom progression argue strongly against worsening heart failure 1

Important Caveats

Do not automatically attribute all lower extremity findings to heart failure in HFpEF patients. 1 The 2023 ACC Expert Consensus specifically warns against this common pitfall, emphasizing that many patients have noncardiovascular entities causing their lower extremity findings. 1

Avoid empirically increasing diuretics for asymptomatic, stable lower extremity changes without evidence of true volume overload, as this can lead to:

• Prerenal azotemia and worsening renal function 1
• Electrolyte abnormalities 1, 2
• Neurohormonal activation that may worsen long-term outcomes 1

If the mottling represents livedo reticularis (a reticular, net-like vascular pattern), consider less common causes including:

• Antiphospholipid syndrome or other vasculopathies 1
• Cholesterol emboli (though typically acute, not stable for months) 1
• Vasculitis (would typically have systemic symptoms) 1