Introduction Myocardial infarction with non-obstructive coronary arteries (MINOCA) constitutes a heterogenous condition with different coronary, cardiac and non-cardiac etiologies. Cardiovascular magnetic resonance imaging (CMR) has emerged as an important diagnostic tool in recent years and is now recommended in patients with MINOCA as a working diagnosis. However, despite early CMR following admission for MINOCA, no cause can be found in around 25% of all patients. A pathophysiological mechanism may be diffuse global coronary microvascular dysfunction (CMD) which has emerged as an important cause of myocardial ischemia. Quantitative adenosine stress CMR perfusion mapping allows for absolute quantification of myocardial perfusion, reflecting CMD in the absence of obstructive coronary disease in MINOCA patients. Purpose To study the presence of CMD in MINOCA patients with an initial normal CMR scan compared to healthy controls. Methods Patients from the multicenter myocardial infarction in our city with normal Coronaries 2 (SMINC-2) study, with a normal CMR scan 2–4 days after hospitalization, and healthy age- and sex-matched controls underwent stress perfusion at 1.5T (MAGNETOM Aera). Native rest T1 and T2 short-axis maps were acquired. Quantitative perfusion maps were acquired during adenosine stress (140 micrograms/kg/min) and at rest following an intravenous contrast bolus (0.05 mmol/kg of gadoteric acid, Gd-DOTA). Post contrast T1 maps were acquired after intravenous contrast (total dose 0.2 mmol/kg) rendering extracellular volume (ECV) maps. Global native T1, T2, ECV and rest and stress perfusion values were acquired by averaging segmental values per patient. Myocardial perfusion reserve (MPR) was calculated as perfusion in stress divided by rest. Values were presented as mean±standard deviation and compared with the independent t-test in normally distributed data, and with the Mann-Whitney U test in non-normally distributed data. Clinical data regarding cardiovascular risk factors, smoking and medications were presented as numbers (percentages) and compared with Fisher's exact test. Rate pressure product (RPP) was calculated as systolic blood pressure multiplied by heart rate in rest and stress. Results In total, 15 patients (59±16 years old, 60% female), and 15 healthy age- and sex-matched controls, were included. There was a trend towards higher incidence of hypertension in patients compared to controls, however no difference in other risk factors (Table 1). Compared to controls, MINOCA patients had lower perfusion in stress (Figure 1). There was no difference in global native T1, T2, ECV, rest perfusion, MPR or hemodynamic parameters between the MINOCA patients and the controls (p>0.05 for all, Table 1). Conclusions Myocardial stress perfusion is lower in MINOCA patients with a normal initial CMR scan compared to age- and sex-matched controls suggesting CMD as a possible pathophysiological mechanism in MINOCA. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Swedish Heart and Lung Foundation
Background: Myocardial infarction with nonobstructive coronary arteries (MINOCA) constitutes a working diagnosis. Early cardiovascular magnetic resonance imaging (CMR) is recommended, however cannot provide a diagnosis in 25% of MINOCA cases. A pathophysiological mechanism may be coronary microvascular dysfunction (CMD). Quantitative stress CMR perfusion mapping allows for quantification of myocardial perfusion, which may detect CMD in the absence of obstructive coronary artery disease. However, it is unknown if CMD is present post-convalescence in suspected MINOCA patients. Purpose: To evaluate the presence of CMD after convalescence in patients with suspected MINOCA. Methods: Patients from the multicenter Stockholm Myocardial Infarction with Normal Coronaries (SMINC) 2 study with a normal CMR scan 2-4 days after hospitalization, and healthy age- and sex-matched volunteers underwent stress CMR during long-term follow-up. Cardiovascular risk factors, medication and symptoms of myocardial ischemia measured by the Seattle Angina Questionnaire 7, were registered. Results: In total, 15 patients with suspected MINOCA (59±7 years old, 60% female), and 15 healthy age- and sex-matched volunteers, underwent CMR. Patients with suspected MINOCA had lower global stress perfusion (2.83±1.8 vs 3.53±0.7 ml/min/g, p=0.02). There was neither differences in other CMR parameters such as global rest perfusion and myocardial perfusion reserve, hemodynamic parameters nor cardiovascular risk factors except for higher statin use in the MINOCA patient group compared to volunteers. Conclusions: Global stress perfusion is lower in MINOCA patients with a normal initial CMR scan during follow-up, compared to age- and sex-matched volunteers, suggesting CMD as a possible pathophysiological mechanism in MINOCA.
Severe Covid-19 may cause a cascade of cardiovascular complications beyond viral pneumonia. The severe inflammation may affect the microcirculation which can be assessed by cardiovascular magnetic resonance (CMR) imaging using quantitative perfusion mapping and calculation of myocardial perfusion reserve (MPR). Furthermore, native T1 and T2 mapping have previously been shown to identify changes in myocardial perfusion by the change in native T1 and T2 during adenosine stress. However, the relationship between native T1, native T2, ΔT1 and ΔT2 with myocardial perfusion and MPR during long-term follow-up in severe Covid-19 is currently unknown. Therefore, patients with severe Covid-19 (n = 37, median age 57 years, 24% females) underwent 1.5 T CMR median 292 days following discharge. Quantitative myocardial perfusion (ml/min/g), and native T1 and T2 maps were acquired during adenosine stress, and rest, respectively. Both native T1 (R2 = 0.35, p < 0.001) and native T2 (R2 = 0.28, p < 0.001) correlated with myocardial perfusion. However, there was no correlation with ΔT1 or ΔT2 with MPR, respectively (p > 0.05 for both). Native T1 and native T2 correlate with myocardial perfusion during adenosine stress, reflecting the coronary circulation in patients during long-term follow-up of severe Covid-19. Neither ΔT1 nor ΔT2 can be used to assess MPR in patients with severe Covid-19.
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