Diagnosis, risk factors and quality-of-life in patients with myocardial infarction and normal coronary arteries

Abstract

Background: Myocardial infarction with normal coronary arteries (MINCA) is a common condition that mostly affects middle-aged women. The pathogenesis is complex and includes various mechanisms that need to be explored for appropriate diagnosis and treatment. Patients with MINCA often complain about low energy and appear to be distressed. Previous studies in MINCA with control groups were lacking when the Stockholm myocardial infarction and normal coronaries (SMINC) study started.

Aims: To describe cardiac magnetic resonance (CMR) imaging findings, background characteristics, atherosclerosis markers and quality-of-life (QoL) in patients with MINCA. The intention is to better understand and improve the management of this group of patients.

Specific aims, methods and results: Study 1. The aim was to report the true prevalence of myocarditis and MINCA with or without myocardial infarction by using CMR. We investigated 152 patients 35-70 years and found that 67% had a normal CMR, 19% had signs of myocardial necrosis and 7% had signs of myocarditis. Twenty-two percent of all MINCA with a normal CMR fulfilled the Mayo clinical diagnostic criteria for TS. The CMR was performed a median of 12 days (6-28 days) after the acute event. Study 2. The aim was to describe the risk factors by analysing the case record form (CRF) and different investigations performed during the 3 months follow up after the acute event in patients with MINCA and compare those with two control groups. We analysed blood samples, reactive hyperaemia index (RHI) and intima-media thickness (IMT) by using EndoPAT® (Itamar Medical Ltd) and ultrasound of the carotids. The results showed that MINCA was associated with similar risk factors as in coronary heart disease (CHD) patients except for a more favourable lipid profile. The atherosclerotic burden in MINCA, measured as RHI and IMT, were within the normal range and similar to both healthy and CHD controls. Psychiatric disorders were more common in patients with MINCA and TS than those without TS and more than half of all MINCA patients recalled physical and emotional stress before admission. Study 3. The aim was to describe the physical capacity and QoL 6 weeks to 3 months after the acute event in MINCA compared to both control groups using an exercise bicycle stress test and Short Form (SF)-36. The findings showed that patients with MINCA had a lower exercise capacity and QoL compared with healthy controls. Compared with CHD controls the results showed better exercise capacity in MINCA but lower mental and vitality scores in the mental component of SF-36, otherwise the dimensions were similar. Study 4: The aim was to evaluate mental health in MINCA patients and compare them with two control groups by using two different surveys 3 months after the acute event; the Beck Depression Inventory (BDI) and the Hospital Anxiety and Depression scale (HADS). Our findings showed that anxiety and depression were common with prevalence rates similar to patients with CHD. Anxiety was more common in patients with MINCA and TS than those without TS.

Conclusions: CMR imaging is an important tool that can help us to identify the different underlying diagnoses in MINCA and enable a more adequate treatment. Patients with MINCA do not have signs of early or generalized atherosclerosis and they share a number of cardiovascular risk factors with patients who have CHD, including high prevalence of anxiety and depression. There is also a decline in QoL similar to that of CHD patients and in some perspectives even worse in the domain of mental health. Altogether these findings show a high vulnerability to mental stress in patients with MINCA. The lack of clarity regarding diagnosis and treatment can also increase the stress and therefore highlight the need for a change in the management care of patients with MINCA, not only in the hospital but also after being discharged. Performing CMR early (2 weeks from presentation) and follow-up care in in a similar way as in patients with CHD will probably decrease the mental stress and improve QoL.