Myocardium Microalterations Index (MMI) in patients with haemochromatosis attending Nenagh hospital for venesection
Mohammed Ali, Ahsan Sarfaz, Eoin Ryan and Manus Moloney
University of Limerick Hospital Group Nenagh
Haemochromatosis is the abnormal accumulation of iron in parenchymal tissue, leading to organ damage. Cardiomyopathy is a recognised complication. Fatigue is a common symptom of Haemochromatosis (74%), whether fatigue may be linked to subclinical myocardial dysfunction is unknown.
The aim is to use the ECG dispersion mapping (ECG-DM) in a preliminary study to analyze myocardial electrophysiological properties in Haemochromatosis patients attending Nenagh Hospital for venesection. ECG-DM is a novel technique that analyzes low-amplitude ECG oscillations and reports them as the myocardial micro-alternation index (MMI), which is expressed as a percentage(1). If pathological micro-deviations are present throughout the entire myocardium, the MMI is 100%, whereas an MMI of 0% indicates a total absence of abnormal microdeviations. This technique may have a role in assessing individual risks of cardiovascular disease. The normal mean Myocardium Microalteration Index (MMI) is less than 15%. MMI of 15% to 17% suggests the possibility of intermediate cardiac risk, and greater than 17% represents increased risk of cardiac disease with significant electrophysiological deviation. MMI in the population of healthy persons increases with age(1).
We carried out ECG dispersion mapping in 38 patients with hemochromatosis attending Nenagh hospital for routine venesection. Myocardium Microalterations Index (MMI) was recorded for each patient.
79 % of patients were males,while the females represent 21% of the cases.The mean age for all the group was 64.5 . 87% (33) of patients had MMI of less than 15%. 8%(3) had MMI between 15 -17% and only 5%(2) had MMI of 20%. Of these patients the first is a male age 40 with fatigue as main symptom, ferritin 564 at presentation, transferring saturation 74%. No independent risk factors for cardiac disease. The second patient is a 62 year old female, C282Y homozygous, ferritin 308 at presentation, transferrin saturation 88%. She complained of shortness of breath 2009, cardiac catheter negative for coronary artery disease. Chest x ray normal. No risk factors for heart disease other than age.
Most patients of haemochromatosis attending Nenagh Hospital for venesection have normal MMI which may indicate low risk of myocardial disease but may also reflect early diagnosis and early intiation of therapy. Patients with the highest MMI in this small preliminary study exhibited symptoms of fatigue and cardiac dysfunction in the absence of independent cardiac risk factors. Further studies are needed to evaluate MMI utility in haemochromatosis as a method of detecting subclinical cardiac disease.