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Clinically Unrecognized Myocardial Scars Detected by MRI
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Radiology.
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A high percentage of unrecognized myocardial infarctions (UMIs) seen at delayed-enhanced magnetic resonance imaging (DE-MRI) are not detected by ECG. DE-MRI-detected UMIs are independent predictors of cardiovascular events in patients with coronary artery disease. In an elderly population, subjects with DE-MRI-detected UMIs do not have increased Framingham risk score or increased prevalence of artery stenosis in whole-body MR angiography as patients with recognized myocardial infarctions (RMI). Further investigation on the pathogenesis of DE-MRI-detected UMIs focus on the need to decide the management of these subjects.

From the Prospective Investigation of the Vasculature in Uppsala Seniors, 248 subjects underwent cardiac MRI at age 70 and from these, 185 underwent a 5-year follow-up MR. DE-MRI-detected UMIs had lower signal intensity than RMIs probably reflecting different composition of their tissues. Subjects with UMI scar had increased levels of NT-proBNP, a predictor of increased risk of cardiovascular events. After 5 years, UMI scars were in their majority seen on the same location and with the same size, and their prevalence increased. Subjects with an UMI did not differ from subjects without a scar in terms of coronary stenosis assessed by computed tomography angiography or signs of ischemia on exercise test.

In conclusion, DE-MRI-detected UMI scars are a frequent finding in an elderly population and its prevalence increases with age. The increased levels of NT-proBNP indicate that subjects with an UMI might have an increased rate of future cardiovascular events but the findings that these scars might have a different contrast distribution volume on MRI and that they are not related to CAD are indicators that they probably have a different etiology from RMIs. The prognosis of DE-MRI detected UMI scars in the general population is still unknown and therefore the clinical management of these individuals is yet to be defined.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. , p. ??
Keywords [en]
unrecognized myocardial scars, myocardial infarction, epidemiology, magnetic resonance, computed topographic coronary angiography, exercise test, NT-proBNP
National Category
Radiology, Nuclear Medicine and Medical Imaging Cardiac and Cardiovascular Systems
Research subject
Radiology; Cardiology
Identifiers
URN: urn:nbn:se:uu:diva-172017ISBN: 978-91-506-2283-6 (print)OAI: oai:DiVA.org:uu-172017DiVA, id: diva2:513404
Public defence
2012-05-21, Grönwallsalen, Akademiska Sjukhuset, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2012-04-26 Created: 2012-04-01 Last updated: 2012-04-26Bibliographically approved
List of papers
1. Signal Intensity of Myocardial Scars at Delayed-enhanced MRI
Open this publication in new window or tab >>Signal Intensity of Myocardial Scars at Delayed-enhanced MRI
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2009 (English)In: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 50, no 6, p. 652-7Article in journal (Refereed) Published
Abstract [en]

Background: Traditionally, unrecognized myocardial infarction (UMI) is defined as the appearance, in a non-acute setting, of a new diagnostic Q wave. In the recent past, delayed-enhanced magnetic resonance imaging (DE-MRI) has provided a new imaging method for evaluating myocardial viability and to detect myocardial scars. Purpose: To investigate differences in tissue characteristics between UMI and recognized myocardial infarction (RMI) scars, by assessing the signal intensity (SI) detected by DE-MRI. Material and Methods: A randomized subgroup of 259 subjects from the Prospective Investigation of the Vasculature of Uppsala Seniors (PIVUS) study was submitted to cardiac magnetic resonance imaging (MRI). DE-MRI-detected myocardial scars were divided in two groups, UMI and RMI, according to the hospital medical records. The scars detected by DE-MRI were analyzed by measuring SI ratio of scar tissue to normal myocardium. Results: The mean SI ratio in the UMI group (4.5+/-3.0, mean+/-SD) was lower than in the RMI group 8.9+/-5.1 (P-value = 0.001). This difference was still significant (P <0.0001) after adjustment for gender, body mass index, time of image acquisition after gadolinium administration, scar transmurality, or total myocardial infarction mass. Conclusion: The difference in the SI ratio of the scars between the two groups most likely reflects a different contrast distribution volume of the tissues, which might indicate that UMI and RMI tissues diverge in tissue composition.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-103590 (URN)10.1080/02841850902933081 (DOI)000267256400011 ()19449231 (PubMedID)
Available from: 2009-05-20 Created: 2009-05-20 Last updated: 2017-12-13Bibliographically approved
2. Unrecognized myocardial scars detected by delayed-enhanced MRI are associated with increased levels of NT-proBNP
Open this publication in new window or tab >>Unrecognized myocardial scars detected by delayed-enhanced MRI are associated with increased levels of NT-proBNP
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2011 (English)In: Coronary Artery Disease, ISSN 0954-6928, E-ISSN 1473-5830, Vol. 22, no 3, p. 158-164Article in journal (Refereed) Published
Abstract [en]

OBJECTIVES: Patients with unrecognized myocardial infarction (UMI) scars detected by delayed-enhanced magnetic resonance imaging (DE-MRI) have a decreased left ventricular ejection fraction and an increased left ventricular mass. N-terminal pro-brain natriuretic peptide (NT-proBNP) is a marker of heart failure, and troponin I (TnI) is a marker of myocardial injury. The primary aim of this study was to investigate whether NT-proBNP plasma levels (in addition to ejection fraction) differed in patients with UMI scars compared with normal participants. The second aim was to compare whether the TnI levels differed in those two groups. METHODS: Data from the Prospective Investigation of Vasculature in Uppsala Seniors study were used. The participants who had undergone cardiac MRI were included in this study (n=248). Patients were divided into three groups depending on the existence of a myocardial infarction (MI) scar in DE-MRI and their earlier history of MI. In all the patients, a peripheral blood sample was collected and the plasma levels of NT-proBNP and TnI were determined. RESULTS: Patients with UMI had higher plasma levels of NT-proBNP (median 140.2 ng/l; 25th-75th percentiles: 79-225.5) than no-MI participants (median 94.9 ng/l; 25th-75th percentiles: 59.2-144.2; P=0.01) and lower levels than patients with recognized MI (median 310.4 ng/l; 25th-75th percentiles: 122.6-446.5; P=0.02). Plasma TnI values did not differ among the three groups. CONCLUSION: Patients with UMI scars detected by DE-MRI have increased plasma levels of NT-proBNP that is known to correlate with an increased risk of future cardiovascular adverse events.

Keywords
epidemiology, infarction, prognosis, silent, troponin I, viability
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-141510 (URN)10.1097/MCA.0b013e328342c72e (DOI)000289506000006 ()21200318 (PubMedID)
Available from: 2011-01-12 Created: 2011-01-12 Last updated: 2017-12-11Bibliographically approved
3. The number of unrecognized myocardial infarction scars detected at DE-MRI increase during a 5-year follow-up
Open this publication in new window or tab >>The number of unrecognized myocardial infarction scars detected at DE-MRI increase during a 5-year follow-up
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2017 (English)In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 27, no 2, p. 715-722Article in journal (Refereed) Published
Abstract [en]

Objectives

In an elderly population, the prevalence of unrecognized myocardial infarction (UMI) scars found via late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) imaging was more frequent than expected. This study investigated whether UMI scars detected with LGE-CMR at age 70 would be detectable at age 75 and whether the scar size changed over time.

Methods

From 248 participants that underwent LGE-CMR at age 70, 185 subjects underwent a follow-up scan at age 75. A myocardial infarction (MI) scar was defined as late enhancement involving the subendocardium.

Results

In the 185 subjects that underwent follow-up, 42 subjects had a UMI scar at age 70 and 61 subjects had a UMI scar at age 75. Thirty-seven (88 %) of the 42 UMI scars seen at age 70 were seen in the same myocardial segment at age 75. The size of UMI scars did not differ between age 70 and 75.

Conclusions

The prevalence of UMI scars detected at LGE-CMR increases with age. During a 5-year follow-up, 88 % (37/42) of the UMI scars were visible in the same myocardial segment, reassuring that UMI scars are a consistent finding. The size of UMI scars detected during LGE-CMR did not change over time.

Keywords
Unrecognized myocardial infarction, delayed-enhancement magnetic resonance imaging, follow-up study, epidemiology
National Category
Radiology, Nuclear Medicine and Medical Imaging Cardiac and Cardiovascular Systems
Research subject
Radiology; Cardiology; Epidemiology
Identifiers
urn:nbn:se:uu:diva-172069 (URN)10.1007/s00330-016-4439-7 (DOI)000392142000032 ()27255402 (PubMedID)
Funder
Swedish Research Council, k2013-64x-08268-3
Available from: 2012-04-02 Created: 2012-04-02 Last updated: 2017-12-07Bibliographically approved
4. Clinically unrecognized myocardial scars detected by MR are not associated with coronary artery disease
Open this publication in new window or tab >>Clinically unrecognized myocardial scars detected by MR are not associated with coronary artery disease
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Background:

We have previously discovered an unexpected high prevalence of unrecognized myocardial infarction (UMI) scars by delayed-enhanced magnetic resonance imaging (DE-MRI) in the general elderly population. We now investigated if those UMIs were associated with coronary artery disease (CAD).

 

Methods:

Eighty-eight subjects from the PIVUS study (age 75-years) who had been investigated with DE-MRI (45 with UMI and 43 without DE-MRI-detected scars) underwent coronary computed tomography angiography (CTA) to assess Agatston calcium score and coronary artery stenosis. Of those, 65 also performed an exercise ECG test.

 

Results:

No differences were found between the subjects with UMI and the group without DE-MRI-detected scars regarding the number of coronary artery segments with significant stenosis, Agatston calcium score, or degree of ST-depression at the exercise test.

 

Conclusion:

DE-MRI-detected UMI scars do not have an increased prevalence of coronary artery stenosis or signs of myocardial ischemia at exercise test when compared to a control group. These findings indicate that UMI scars in general are not related to CAD.

 

Keywords
Unrecognized myocardial infarction; delayed-enhanced magnetic resonance imaging; coronary computed tomography angiography; exercise test; coronary artery disease
National Category
Radiology, Nuclear Medicine and Medical Imaging Cardiac and Cardiovascular Systems
Research subject
Radiology; Cardiology; Epidemiology
Identifiers
urn:nbn:se:uu:diva-172070 (URN)
Available from: 2012-04-02 Created: 2012-04-02 Last updated: 2012-04-02

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