Does a low stroke volume index of 23.69 ml/m2 indicate decompensation and progression of diastolic dysfunction in a patient with iron deficiency and normal ABI results?

Does Low Stroke Volume Index Indicate Decompensation in Diastolic Dysfunction?

Your stroke volume index of 23.69 ml/m² is severely reduced and indicates significant cardiac compromise, but this alone does not definitively prove progression beyond grade I diastolic dysfunction—you need comprehensive echocardiographic assessment including E/e' ratio, left atrial volume index, and tissue Doppler imaging to grade diastolic dysfunction severity. 1, 2

Understanding Your Stroke Volume Index

Your stroke volume index is approximately 40% below the normal range (normal is typically 35-65 ml/m²), representing substantial impairment in cardiac performance that demands urgent evaluation at a cardiovascular center. 2

Critical context for your situation:

• Iron deficiency without anemia can independently cause severely reduced stroke volume index through multiple mechanisms: decreased oxygen delivery forcing compensatory hemodynamic stress, impaired oxidative metabolism in cardiac myocytes, and reduced exercise capacity even with normal hemoglobin. 1, 2, 3

• Your hemoglobin of 14.0 g/dL is technically normal but at the lower limit, while your ferritin of 41 μg/L indicates depleted iron stores that warrant treatment regardless of hemoglobin level. 3

• The American College of Cardiology explicitly states that iron deficiency without overt anemia should be treated, as it causes lethargy, reduced performance, and impaired cardiac function. 1, 3

Grading Diastolic Dysfunction Requires Specific Parameters

You cannot determine diastolic dysfunction grade from stroke volume index alone. The European Society of Cardiology diagnostic criteria for heart failure with preserved ejection fraction (which includes diastolic dysfunction) require: 4

• E/e' ratio via tissue Doppler: E/e' >15 confirms diastolic dysfunction; E/e' 8-15 requires additional testing; E/e' <8 suggests normal diastolic function. 5, 4

• Left atrial volume index (LAVI): >34 ml/m² indicates chronically elevated filling pressures. 5

• Additional markers: Elevated natriuretic peptides (BNP/NT-proBNP), increased LV mass index, atrial fibrillation on ECG. 4

The relationship between diastolic dysfunction severity and iron deficiency is well-established: iron deficiency prevalence increases dramatically with worsening diastolic dysfunction grades (E/e' ≤8: 44.8% vs. E/e' 9-14: 53.2% vs. E/e' ≥15: 86.5%). 6

Your Ankle-Brachial Index Results

Your ABI values (posterior tibial 1.18-1.19, dorsalis pedis 1.15-1.17) are mildly elevated, not low. 5

• Normal ABI is 0.90-1.40; values >1.40 suggest arterial stiffness from calcification. 5
• Your values of 1.15-1.19 are at the upper end of normal, which may reflect increased arterial stiffness but do not indicate peripheral arterial disease. 5
• This finding is consistent with the vascular effects of iron overload or chronic disease states that can increase vascular stiffness. 5

Immediate Diagnostic Priorities

Before your cardiovascular center visit, obtain these specific tests:

1. Complete echocardiogram with tissue Doppler imaging to measure:

   • E/e' ratio (most critical for grading diastolic dysfunction) 5, 4
   • Left atrial volume index 5, 4
   • LV mass index 4
   • Ejection fraction and LV end-diastolic volume index 4

2. Natriuretic peptides (BNP or NT-proBNP): Elevated levels support diagnosis of heart failure and correlate with diastolic dysfunction severity, though one study showed poor correlation with cardiac iron loading specifically. 5, 4

3. Complete iron panel with transferrin saturation: Your ferritin of 41 μg/L indicates iron deficiency, but TSAT <20% would confirm inadequate iron for erythropoiesis and strengthen the indication for treatment. 5, 1, 3

4. Reticulocyte count: Helps assess bone marrow response and functional iron availability. 3

Treatment Implications for Your Situation

Intravenous iron therapy is indicated for your iron deficiency, particularly given your cardiac symptoms and severely reduced stroke volume index. 5, 1, 2

• The European Society of Cardiology recommends IV iron (specifically ferric carboxymaltose) for symptomatic heart failure patients with iron deficiency (ferritin <100 μg/L or ferritin 100-300 μg/L with TSAT <20%), as it improves NYHA functional class, 6-minute walk test, quality of life, and reduces hospitalizations. 5

• Oral iron is inadequate for cardiac dysfunction—IV iron therapy has proven cardiac benefit independent of anemia correction. 2

• Calculate your total iron need based on hemoglobin and body weight: with Hb 14.0 g/dL, you would typically receive 500-1000 mg iron depending on body weight. 5

• Expect improvement in exercise tolerance and functional status within weeks of IV iron therapy, with potential dramatic improvement in cardiac function. 2

Common Pitfalls to Avoid

Do not assume your low stroke volume index is solely from diastolic dysfunction progression—iron deficiency independently causes reduced cardiac output through decreased oxygen delivery and impaired myocardial metabolism. 1, 2

Do not wait for anemia to develop before treating iron deficiency—iron depletion causes cardiac compromise before hemoglobin drops, and your ferritin of 41 μg/L already indicates depleted stores requiring treatment. 3

Do not rely on MCV to exclude iron deficiency—your normocytic red cells (MCV 92 fL) represent early iron deficiency before microcytosis develops. 3

Do not check iron parameters within 4 weeks of receiving IV iron—circulating iron interferes with assays and gives falsely elevated results. 3

Coordinating Your Care

Regarding the iron panel ordering issue: Any physician managing your cardiac condition (cardiologist, primary care, or hematologist) can and should order ferritin, transferrin saturation, serum iron, TIBC, and reticulocyte count. 3

• These are standard laboratory tests available at any commercial laboratory. 3
• Given your severely reduced stroke volume index and confirmed iron deficiency, this testing is medically necessary and should not be delayed by administrative barriers. 1, 2

At the cardiovascular center, ensure they:

• Perform comprehensive diastolic function assessment with tissue Doppler E/e' ratio 5, 4
• Consider IV iron therapy given your iron deficiency and cardiac compromise 5, 2
• Evaluate for other causes of reduced stroke volume (valvular disease, cardiomyopathy, restrictive physiology) 5
• Monitor response to iron therapy with repeat echocardiography and functional assessments 4-8 weeks after treatment 2, 3