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The Impact of Iron Deficiency on Disease Severity and Myocardial Function in Cardiac Amyloidosis
Pieter Martens1,2, Lauren Ives1, Christopher Nguyen1
1Department of Cardiovascular Medicine, Heart, Vascular and Thoracic Institute, Cleveland Clinic, Cleveland, Ohio, USA.
Insights
Iron deficiency is common in cardiac amyloidosis. Identifying it using transferrin saturation (TSAT) < 20% indicates worse functional status and right ventricular disease, but not mortality risk.
Area of Science:
- Cardiology
- Hematology
- Internal Medicine
Background:
- Reduced cardiac energy is a hallmark of heart failure, often seen in cardiac amyloidosis (CA).
- Iron deficiency can exacerbate reduced cardiac energy in patients with CA.
- Understanding iron status is crucial for managing CA patients.
Purpose of the Study:
- To determine the prevalence of iron deficiency in cardiac amyloidosis patients.
- To investigate the association between iron deficiency definitions and clinical outcomes in CA.
- To assess the impact of iron deficiency on cardiac function and mortality in CA.
Main Methods:
- Retrospective analysis of a single tertiary care center CA registry.
- Iron deficiency defined by classic (ferritin/TSAT) and TSAT-based (< 20%) criteria.
- Evaluation of functional status, cardiac function (echocardiography, CMR), and mortality.
Main Results:
- 56-58% of 393 CA patients had iron deficiency by either definition.
- TSAT < 20% was linked to worse functional status and cardiac function.
- TSAT < 20% correlated with more pronounced right ventricular failure, but not increased mortality.
Conclusions:
- Iron deficiency is prevalent in cardiac amyloidosis.
- A TSAT < 20% identifies patients with worse functional status and RV disease.
- Iron deficiency in CA, by these definitions, does not predict all-cause mortality.
Background:
Reduced cardiac energy is a hallmark feature of heart failure and is common in cardiac amyloidosis (CA) and can be aggravated by the presence of iron deficiency.
Methods:
Retrospective analysis of a single tertiary care center CA registry. Prevalence of iron deficiency was determined based on two definitions: (1) Classic definition, ferritin < 100 µg/L irrespective of transferin saturation (TSAT) or ferritin between 100 and 300 µg/L with a TSAT < 20%, and (2) TSAT-based definition, TSAT < 20%.
Results:
Out of a total of 393 CA patients who had a full set of iron indices (44% light chain [AL]-CA, 50% transthyretin [ATTR]-CA, remainder other or unspecified CA subtype), 56% had iron deficiency according to the classic definition and 58% according to the TSAT definition, with similar prevalence in AL-CA vs ATTR-CA (p = .135). Per both definitions 58% had anemia. Only the TSAT-based definition was associated with worse functional status (p = .039) and worse cardiac function. CA patients with a TSAT < 20% illustrated features of more pronounced right ventricular (RV) failure including lower TAPSE on echocardiography, lower RV ejection fraction and RV stroke volume index on CMR, increased right-sided filling pressures, lower pulmonary artery pulsatility index, and higher RAP/PCWP ratio by right heart catheterization. Neither the classic nor the TSAT-based definition was associated with a higher risk of all-cause mortality after covariate adjustment.
Conclusion:
Iron deficiency is common in cardiac amyloidosis and, when identified with a TSAT < 20%, is associated with worse functional status and more pronounced RV disease, but not with a higher risk of all-cause mortality.
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