The relation between hypointense core, microvascular obstruction and intramyocardial haemorrhage in acute reperfused myocardial infarction assessed by cardiac magnetic resonance imaging

Abstract

BackgroundIntramyocardial haemorrhage (IMH) and microvascular obstruction (MVO) represent reperfusion injury after reperfused ST-elevation myocardial infarction (STEMI) with prognostic impact and “hypointense core” (HIC) appearance in T2-weighted images. We aimed to distinguish between IMH and MVO by using T2*-weighted cardiovascular magnetic resonance imaging (CMR) and analysed influencing factors for IMH development.Methods and resultsA total of 151 patients with acute STEMI underwent CMR after primary angioplasty. T2-STIR sequences were used to identify HIC, late gadolinium enhancement to visualise MVO and T2*-weighted sequences to detect IMH. IMH+/IMH− patients were compared considering infarct size, myocardial salvage, thrombolysis in myocardial infarction (TIMI) flow, reperfusion time, ventricular volumes, function and pre-interventional medication. Seventy-six patients (50 %) were IMH+, 82 (54 %) demonstrated HIC and 100 (66 %) MVO. IMH was detectable without HIC in 16 %, without MVO in 5 % and HIC without MVO in 6 %. Multivariable analyses revealed that IMH was associated with significant lower left ventricular ejection fraction and myocardial salvage index, larger left ventricular volume and infarct size. Patients with TIMI flow grade ≤1 before angioplasty demonstrated IMH significantly more often.ConclusionsIMH is associated with impaired left ventricular function and higher infarct size. T2 and HIC imaging showed moderate agreement for IMH detection. T2* imaging might be the preferred CMR imaging method for comprehensive IMH assessment.Key Points• Intramyocardial haemorrhage is a common finding in patients with acute reperfused myocardial-infarction.• T2*imaging should be the preferred CMR method for assessment of intramyocardial haemorrhage.• Intramyocardial haemorrhage can be considered as an important influencing factor on patient’s outcome.

Diagnostic performance of T1 and T2 mapping to detect intramyocardial hemorrhage in reperfused ST‐segment elevation myocardial infarction (STEMI) patients

“…IMH was defined as a hypointense core on the maps with a <20 msec as previously validated and subsequently used in several clinical STEMI studies …”

“…Both MVO and IMH are associated with larger myocardial infarct (MI) sizes, adverse left ventricular (LV) remodeling and poor clinical outcomes, as recently summarized in two meta‐analyses . Cardiac MR within the first week following STEMI using imaging has been shown to detect IMH in animal models of acute MI and a threshold value of T* <20 msec has subsequently been used in several clinical studies as the reference for IMH . Although imaging is currently the reference standard for the detection of IMH, it is prone to motion, flow and off‐resonance artifacts .…”

“…T 2 ‐weighted short tau inversion recovery (STIR) imaging, which has been used to delineate the area‐at‐risk (AAR) in reperfused STEMI patients, has also been used to detect IMH as the presence of a hypointense core within the AAR . However, STIR imaging has been shown to have a lower diagnostic performance for detecting IMH when compared to imaging . Native T 1 and T 2 maps have been explored as alternative methods for quantifying the AAR in reperfused STEMI patients and MVO and IMH can also manifest as a hypointense core on the native T 1 and T 2 maps .…”

“…However, the diagnostic performance of native T 1 and T 2 maps to detect the presence of IMH and MVO following STEMI has not been directly compared. Therefore, the main aim of this study was to investigate the performance of hypointense core on the native T 1 (referred to as T 1 throughout the article for simplicity) and T 2 maps to detect IMH within the first week in reperfused STEMI patients, using mapping as the reference standard for IMH . Secondly, we also aimed to assess the performance of the hypointense core on the T 1 and T 2 maps to detect early and late MVO, using gadolinium enhancement as the reference standard for MVO …”

Coronary Thermodilution Waveforms After Acute Reperfused ST‐Segment–Elevation Myocardial Infarction: Relation to Microvascular Obstruction and Prognosis

“…Microvascular obstruction was defined as a dark zone on early gadolinium enhancement imaging 1, 3, and 5 minutes postcontrast injection that remained present within an area of late gadolinium enhancement at 15 minutes. On the T2* CMR maps, a region of reduced signal intensity within the infarcted area, with a T2* value of <20 milliseconds17, 18, 19, 20 was considered to confirm the presence of myocardial hemorrhage.…”