Detection of papillary muscle infarction by late gadolinium enhancement: incremental value of short-inversion time vs. standard imaging

Simplified image acquisition and detection of ischemic and non-ischemic myocardial fibrosis with fixed short inversion time magnetic resonance late gadolinium enhancement

OBJECTIVES

Late gadolinium enhancement with fixed short inversion time (LGEshort) provides excellent tissue contrast with dark scar and bright blood pool and does not need prior myocardial nulling. We hypothesize better visibility of ischemic scars and equal visibility of non-ischemic LGE in LGEshort compared to clinically established LGE (LGEstandard).

METHODS

LGEshort and LGEstandard were retrospectively evaluated in 179 patients (3043 segments) with suspected or known coronary artery disease by four blinded readers (reader A: most experienced - D: least experienced). The amount of ischemic and non-ischemic LGE as well as visibility (4: very good - 1: poor) of ischemic LGE was visually assessed.

RESULTS

All readers detected more infarcted segments in LGEshort compared to LGEstandard (378 segments reported as infarcted; A:p = 0.5, B:p = 0.8, C,D:p = 0.03). Scar visibility was scored higher in LGEshort by all readers (A,B:p = 0.03; C,D:p = 0.02), especially for subendocardial infarcts (A,B:p = 0.04, C,D:p = 0.02). Less experienced readers detected significantly more infarcted papillary muscles (C:p = 0.02, D:p = 0.03) in a shorter reading time in LGEshort (C:p = 0.04, D:p = 0.02). Non-ischemic LGE was equally visible in both sequences (A:p = 0.9, B:p = 0.8, C,D:p = 0.6).

CONCLUSIONS

LGEshort detects more ischemic LGE with improved scar visibility compared to LGEstandard, independent of experience level. The visibility of non-ischemic LGE is equivalent to LGEstandard. Less experienced readers can diagnose ischemic and non-ischemic LGE faster in LGEshort.

ADVANCES IN KNOWLEDGE

LGEshort with its maximal operational simplicity can be used for visualization of all types of fibrosis - ischemic and non-ischemic - instead of LGEstandard, independent of experience level.

Dark-blood late gadolinium enhancement CMR improves detection of papillary muscle fibrosis in patients with mitral valve prolapse

PURPOSE

Papillary muscle fibrosis may act as an arrhythmogenic substrate in patients with mitral valve prolapse (MVP). Previous studies used conventional bright-blood late gadolinium enhancement cardiovascular magnetic resonance (LGE CMR) imaging to assess papillary muscle fibrosis, although this technique suffers from poor scar-to-blood contrast which may limit its sensitivity, in contrast to dark-blood LGE. This study sought to compare bright-blood and dark-blood LGE for the detection of papillary muscle fibrosis in patients with MVP.

METHOD

60 patients with known isolated MVP referred for CMR were prospectively recruited. A routine CMR protocol was used to obtain cine imaging, dark-blood LGE and bright-blood LGE in three long-axis views and a stack of short-axis views. Flow mapping of the proximal aorta was performed to calculate mitral regurgitant volume. Images were analysed for cardiac volumes, ejection fraction, mitral regurgitation severity, MVP characteristics (mitral annular disjunction, prolapse volume) and presence of LGE at the papillary muscles and myocardium.

RESULTS

Dark-blood LGE detected significantly more subjects with LGE at the papillary muscles than bright-blood LGE (35% vs 15%, p = 0.002). There was no difference between LGE techniques regarding myocardial (non-papillary muscle) fibrosis (present in 25% each). No statistical differences were observed between patients with or without LGE at the papillary muscles regarding demographics, clinical data (including ventricular arrhythmia) and MVP characteristics. Furthermore, no association was found between LGE at the papillary muscles and at the myocardium.

CONCLUSIONS

Compared to bright-blood LGE, dark-blood LGE CMR improves the detection of LGE at the papillary muscles in patients with MVP.

Usefulness of TI-scout images in the assessment of late gadolinium enhancement in children

BACKGROUND

Cardiovascular magnetic resonance (CMR) late gadolinium enhancement (LGE) requires identification of the normal myocardial nulling time using inversion time (TI)-scout imaging sequence. Although TI-scout images are not primarily used for myocardial assessment, they provide information regarding different signal recovery patterns of normal and abnormal myocardium facilitating identification of LGE in instances where standard LGE images alone are not diagnostic. We aimed to assess the diagnostic performance of TI-scout as compared to that of standard LGE images.

METHODS

CMR studies with LGE imaging in 519 patients (345 males, 1-17 years) were reviewed to assess the diagnostic performance of LGE imaging in terms of the location of LGE and the pathologic entities. The diagnostic performance of the TI-scout and standard LGE imaging was classified into four categories: (1) equally diagnostic, (2) TI-scout superior to standard LGE, (3) standard LGE superior to TI-scout, and (4) complementary, by the consensus of the two observers.

RESULTS

The study cohort consisted of 440 patients with negative LGE and 79 with evidence for LGE. For a negative diagnosis of LGE, TI-scout and standard LGE images were equally diagnostic in 75% of the cases and were complementary in 12%. For patients with LGE, TI-scout images were superior to standard LGE images in 52% of the cases and were complementary in 19%. The diagnostic performance of TI-scout images was superior to that of standard LGE images in all locations. TI-scout images were superior to standard LGE images in 11 of 12 (92%) cases with LGE involving the papillary muscles, in 7 /12 (58%) cases with subendocardial LGE, and in 4/7 (57%) cases with transmural LGE. TI-scout images were particularly useful assessing the presence and extent of LGE in hypertrophic cardiomyopathy (HCM). TI-scout was superior to standard LGE in 6/10 (60%) and was complementary in 3/10 (30%) of the positive cases with HCM.

CONCLUSIONS

TI-scout images enhance the diagnostic performance of LGE imaging in children.

Prognostic relevance and clinical features of papillary muscle infarction with mitral regurgitation in patients with ST segment elevation myocardial infarction

Background

Papillary muscle infarction (PapMI) combined with mitral regurgitation (MR) is a severe complication of ST-segment elevation myocardial infarction (STEMI). The features detected by cardiac magnetic resonance (CMR) imaging in PapMI have not been characterized. The aim of the present study was to assess the incidence, determinants, and the prognostic significance of PapMI with MR at 1-year follow-up in a study of patients with STEMI after primary percutaneous coronary intervention (pPCI).

Methods

We enrolled 209 patients with STEMI reperfused by pPCI (<12 hours after symptom onset) at 2 centers. CMR and echocardiography were performed within 1 week after infarction using a standardized protocol. According to the results of CMR and echocardiography, patients were divided into PapMI with MR, PapMI (PapMI without MR), and non-PapMI groups. The primary clinical endpoint of the study was the occurrence of major adverse cardiovascular events (MACE).

Results

PapMI with MR was found in 27 patients (13%). The existence of PapMI with MR was associated with age (P<0.001), impaired left ventricular ejection fraction (LVEF) (P=0.005), higher SYNTAX score (P=0.002), concentration of troponin I (P<0.001), longer time to reperfusion (P<0.001), more diabetics (P<0.001), and microvascular occlusion (MVO) (P<0.001). Binary logistic regression with stepwise backward selection analysis showed that advanced age, MVO, and impaired LVEF were independent risk factors for PapMI with MR. Patients in the PapMI with MR group had significantly more MACE compared with the PapMI and non-PapMI groups [PapMI with MR, 23 (85.2%) vs. PapMI, 21 (55.3%) vs. non-PapMI, 29 (20.1%)] at 1-year follow-up (P<0.001). However, there were no pronounced differences in mortality rates among the 3 groups (P=0.071).

Conclusions

The presence of PapMI with MR in patients with STEMI is associated with advanced age, MVO, and impaired LVEF, which can increase the rates of MACE.

Clinical value of dark-blood late gadolinium enhancement cardiovascular magnetic resonance without additional magnetization preparation

BACKGROUND

For two decades, bright-blood late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) has been considered the reference standard for the non-invasive assessment of myocardial viability. While bright-blood LGE can clearly distinguish areas of myocardial infarction from viable myocardium, it often suffers from poor scar-to-blood contrast, making subendocardial scar difficult to detect. Recently, we proposed a novel dark-blood LGE approach that increases scar-to-blood contrast and thereby improves subendocardial scar conspicuity. In the present study we sought to assess the clinical value of this novel approach in a large patient cohort with various non-congenital ischemic and non-ischemic cardiomyopathies on both 1.5 T and 3 T CMR scanners of different vendors.

METHODS

Three hundred consecutive patients referred for clinical CMR were randomly assigned to a 1.5 T or 3 T scanner. An entire short-axis stack and multiple long-axis views were acquired using conventional phase sensitive inversion recovery (PSIR) LGE with TI set to null myocardium (bright-blood) and proposed PSIR LGE with TI set to null blood (dark-blood), in a randomized order. The bright-blood LGE and dark-blood LGE images were separated, anonymized, and interpreted in a random order at different time points by one of five independent observers. Each case was analyzed for the type of scar, per-segment transmurality, papillary muscle enhancement, overall image quality, observer confidence, and presence of right ventricular scar and intraventricular thrombus.

RESULTS

Dark-blood LGE detected significantly more cases with ischemic scar compared to conventional bright-blood LGE (97 vs 89, p = 0.008), on both 1.5 T and 3 T, and led to a significantly increased total scar burden (3.3 ± 2.4 vs 3.0 ± 2.3 standard AHA segments, p = 0.015). Overall image quality significantly improved using dark-blood LGE compared to bright-blood LGE (81.3% vs 74.0% of all segments were of highest diagnostic quality, p = 0.006). Furthermore, dark-blood LGE led to significantly higher observer confidence (confident in 84.2% vs 78.4%, p = 0.033).

CONCLUSIONS

The improved detection of ischemic scar makes the proposed dark-blood LGE method a valuable diagnostic tool in the non-invasive assessment of myocardial scar. The applicability in routine clinical practice is further strengthened, as the present approach, in contrast to other recently proposed dark- and black-blood LGE techniques, is readily available without the need for scanner adjustments, extensive optimizations, or additional training.

Cardiac magnetic resonance imaging in heart failure: where the alphabet begins!

Cardiac Magnetic Resonance Imaging has become a cornerstone in the evaluation of heart failure. It provides a comprehensive evaluation by answering all the pertinent clinical questions across the full pathological spectrum of heart failure. Nowadays, CMR is considered the gold standard in evaluation of ventricular volumes, wall motion and systolic function. Through its unique ability of tissue characterization, it provides incremental diagnostic and prognostic information and thus has emerged as a comprehensive imaging modality in heart failure. This review outlines the role of main conventional CMR sequences in the evaluation of heart failure and their impact in the management and prognosis.

Chronic ischemic mitral regurgitation and papillary muscle infarction detected by late gadolinium-enhanced cardiac magnetic resonance imaging in patients with ST-segment elevation myocardial infarction

BACKGROUND

Both papillary muscle infarction (PMI) and chronic ischemic mitral regurgitation (CIMR) are associated with reduced survival after myocardial infarction. The influence of PMI on CIMR and factors influencing both entities are incompletely understood.

OBJECTIVES

We sought to determine the influence of PMI on CIMR after primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) and to define independent predictors of PMI and CIMR.

METHODS

Between January 2011 and May 2013, 263 patients (mean age 57.8 ± 11.5 years) underwent late gadolinium-enhanced cardiac magnetic resonance imaging and transthoracic echocardiography 4 months after PCI for STEMI. Infarct size, PMI, and mitral valve and left ventricular geometric and functional parameters were assessed. Univariate and multivariate analyses were performed to identify predictors of PMI and CIMR (≥grade 2+).

RESULTS

PMI was present in 61 patients (23 %) and CIMR was present in 86 patients (33 %). In patients with PMI, 52 % had CIMR, and in patients without PMI, 27 % had CIMR (P < 0.001). In multivariate analyses, infarct size [odds ratio (OR) 1.09 (95 % confidence interval 1.04-1.13), P < 0.001], inferior MI [OR 4.64 (1.04-20.62), P = 0.044], and circumflex infarct-related artery [OR 8.21 (3.80-17.74), P < 0.001] were independent predictors of PMI. Age [OR 1.08 (1.04-1.11), P < 0.001], infarct size [OR 1.09 (1.03-1.16), P = 0.003], tethering height [OR 19.30 (3.28-113.61), P = 0.001], and interpapillary muscle distance [OR 3.32 (1.31-8.42), P = 0.011] were independent predictors of CIMR.

CONCLUSIONS

The risk of PMI is mainly associated with inferior infarction and infarction in the circumflex coronary artery. Although the prevalence of CIMR is almost doubled in the presence of PMI, PMI is not an independent predictor of CIMR. Tethering height and interpapillary muscle distance are the strongest independent predictors of CIMR.