Global longitudinal strain by feature tracking for optimized prediction of adverse remodeling after ST-elevation myocardial infarction

LV flow kinetics and myocardial deformation following acute infarction: additional predictive value of CMR 4D flow for LV remodeling post-STEMI

BACKGROUND

The exact mechanism underlying myocardial maladaptive changes post ST-elevation myocardial infarction (STEMI) remains unclear.

OBJECTIVES

To assess the impact of the tissue-flow interaction on the development of adverse cardiac remodeling 12 months (M) after acute STEMI.

MATERIALS AND METHODS

49 first-STEMI patients (M:F=26:13; mean age=58±10) prospectively underwent 3T CMR acutely, at 3M and 12M post-STEMI. The CMR protocol included left ventricular (LV) cine-images for LV end-diastolic (LVEDV) and end-systolic (LVESV) volumes, stroke volume (SV) and ejection fraction (LVEF); 4D-flow; LGE imaging. The 3M outcome measures included: 4D-flow derived LV flow kinetic energy indexed to EDV (KEiEDV) and functional flow components [LV- KEiEDV, minimal- KEiEDV, diastolic- KEiEDV, and residual volume (RV), retained inflow (RI), delayed ejection (DE), direct flow (DF)]; global radial, circumferential and longitudinal strain (GRS, GCS, GLS) by feature tracking (FT); infarct size (IS). Adverse LV remodeling (LVremod) was defined by a ≥ 20% increase in LVEDVi at 12M from baseline, in opposition to the non-remodeling group (LVnon-remod). Association between SV, FT-strain, KE and 4D flow parameters were assessed, as well as predictors of adverse remodeling at 12M post-STEMI.

RESULTS

There were 23 LVremod patients. At 3M post-STEMI, LVremod patients had significantly reduced LVEF, increased IS, abnormal FT-strain, systolic KEiEDV, DF and RV compared to LVnon-remod patients. Ther was no significant difference in SV between the 2 groups. FT-strain parameters significantly correlated with DF (GRS: r=0.62; GCS: r=-0.67; GLS: r=-0.58, all p<0.001); RV (GRS: r=-0.56; GCS: r=0.51; GLS: r=0.53, all p<0.001); Peak-A-wave KEiEDV (GRS: r=0.38, p=0.008; GCS: r=-0.30, p=0.038; GLS: r=-0.29, p=0.04); Systolic KEiEDV (GRS: r=0.31, p=0.033, GLS: r=-0.35, p=0.012). DF outperformed conventional LV function parameters (SV and LVEF) in the LVremod prediction. DF and IS were the only independent predictors of 12M adverse remodeling after adjustment for LVEF, SV, FT-strain and KEiEDV parameters.

CONCLUSIONS

Our study suggests a potential early interaction between FT-strain and 4D-flow parameters post-STEMI leading to the development of adverse remodeling. Within the limitations of our sample size, DF and IS were independent predictors of LV remodelling after adjustment for LVEF, SV, FT-strain and KE parameters. These findings suggest that these parameters may contribute to further risk stratification at 3M for the development of adverse remodeling at 12M post-STEMI, above conventional LV function parameters. Larger studies are needed to confirm these results.

Analysis of Risk Factors Associated with Left Ventricular Thrombus in Patients with Ischemic Ventricular Aneurysm: A 3.0 T Cardiac Magnetic Resonance Study

RATIONALE AND OBJECTIVES

Ischemic left ventricular aneurysm (LVA) is associated with left ventricular thrombus (LVT), which poses a significant risk of systemic embolism. This retrospective study aimed to identify clinical and cardiac magnetic resonance (CMR)-related risk factors for LVT in patients with ischemic LVA.

MATERIALS AND METHODS

This study included consecutive hospitalized patients who underwent CMR for ischemic LVA between September 2015 and June 2024. Univariate and multivariate logistic regression analyses were conducted to identify risk factors for LVT in the overall cohort and in two subgroups: acute (AMI) and chronic myocardial infarction (CMI).

RESULTS

Among 384 patients, 108 (28.1%) had LVT. Multivariate logistic regression identified high-sensitivity C reactive protein (hs-CRP) levels (Odds Ratio (OR) 1.05, 95%Confidence Interval (CI) 1.01-1.08, P =0.013), apical aneurysm(OR 4.23, 95%CI 1.15-1.08, P=0.030), infarcted zone peak circumferential strain (PCS) (OR 1.14, 95%CI 1.09-1.21, P<0.001) and extent of late gadolinium enhancement (LGE) (OR 1.35 per 5% increase, 95%CI 1.21-1.50, P <0.001) as significant risk factors for LVT. In patients with AMI, hs-CRP levels, infarcted zone PCS, and extent of LGE were independent predictors of LVT. In patients with CMI, D-dimer, infarcted zone PCS, and extent of LGE emerged as significant predictors.

CONCLUSION

Elevated hs-CRP levels, higher infarcted zone PCS, greater extent of LGE and apical aneurysm are independent risk factors for LVT in patients with ischemic LVA. Both infarcted zone PCS and extent of LGE are significant predictors of LVT in patients with either AMI or CMI complicated with LVA.

Left Atrial Strain for Prediction of Left Ventricular Reverse Remodeling After ST-segment Elevation Myocardial Infarction by Cardiac Magnetic Resonance Feature Tracking

PURPOSE

The study aimed to investigate the potential utility of left atrial (LA) strain by using cardiac magnetic resonance feature-tracking (CMR-FT) to predict left ventricular reverse remodeling (LVRR) following ST-segment elevation myocardial infarction (STEMI).

MATERIALS AND METHODS

Patients with a first STEMI treated by primary percutaneous coronary intervention were consecutively enrolled in the prospective study and underwent CMR scans at 5 days and 4 months. LA global longitudinal strain (reservoir strain [εs], conduit strain [εe], booster strain [εa]) and corresponding strain rate were assessed by CMR-FT using cine images. LVRR was defined as a reduction in the LV end-systolic volume index of >10% from baseline to follow-up. Logistic regression analyses were performed to determine the predictors of LVRR.

RESULTS

Of 90 patients analyzed, patients with LVRR (n=35, 39%) showed higher values of LA strain and strain rate and less extensive infarct size (IS) compared with patients without LVRR (n=55, 61%) at initial and second CMR. The LVRR group demonstrated significant improvements in LV and LA cardiac function over time, especially the obvious increase in LA strain and strain rate. In multivariate logistic regression analyses, εs and εe, together with IS, were independent predictors of LVRR. The combination of εs and IS could optimally predict the LVRR with the highest area under the curve of 0.743.

CONCLUSIONS

Post-STEMI patients with LVRR presented better recovery from cardiac function and LA deformation compared with patients without LVRR. Assessment of εs and εe by using CMR-FT after STEMI enabled prediction of LVRR.

NT-pro-BNP Level is Related to Left Ventricular Remodeling in Patients With Primary Aldosteronism

AIMS

To assess the relationship between the left ventricular remodeling parameters of cardiac magnetic resonance and NT-pro-BNP in patients with primary aldosteronism (PA).

METHODS

Seventy-four PA and 39 essential hypertension patients were prospectively recruited and underwent cardiac magnetic resonance. Plasma NT-pro-BNP was measured before patients underwent cardiac magnetic resonance. Left ventricular remodeling parameters were defined as left ventricular function parameters, T1 mapping parameters, and strain parameters. Differences in continuous variables between two groups were analyzed using Student's t-test or Mann-Whitney U test. Differences in categorical variables between two groups were analyzed by chi-squared test. Spearman's correlation and linear regression were used to analyze the relationships between left ventricular remodeling parameters and plasma NT-Pro-BNP level. P<0.05 was considered as statistically significant.

RESULTS

Patients with PA demonstrated higher NT-pro-BNP [86.0 (49.5, 145.5) vs. 45.0 (28.5, 73.5) pg/mL, P=0.001] and Native T1 (1227±41 vs. 1206±43 ms, P=0.015) level than essential hypertension patients. Compared to patients with normal NT-pro-BNP levels, those with abnormal levels demonstrated different left ventricular remodeling parameters. NT-pro-BNP level was independently related to native T1 (β=0.316, P=0.006), extracellular volume (β=0.419, P<0.001), short-axis global circumferential strain (β=0.429, P<0.001), four-chamber global longitudinal strain (β=0.332, P=0.002), and four-chamber global radial strain (β=-0.334, P=0.004) in patients after adjusting for baseline characteristics.

CONCLUSIONS

NT-pro-BNP level was related to left ventricular remodeling parameters derived from cardiac magnetic resonance in patients with PA. This result implies that clinicians should pay attention to NT-pro-BNP assessment in patients with PA in routine clinical assessment.

Incremental value of high-risk CMR attributes to predict adverse remodeling after ST-segment elevation myocardial infarction across LVEF categories

BACKGROUND

A couple of cardiac magnetic resonance (CMR) attributes strongly predict adverse remodeling after ST-segment elevation myocardial infarction (STEMI); however, the value of incorporating high-risk CMR attributes, particularly, in patients with non-reduced ejection fraction, remains undetermined. This study sought to evaluate the independent and incremental predictive value of a multiparametric CMR approach for adverse remodeling after STEMI across left ventricular ejection fraction (LVEF) categories.

METHODS

A total of 157 patients with STEMI undergoing primary percutaneous coronary intervention were prospectively enrolled. Adverse remodeling was defined as ≥20% enlargement in left ventricular end-diastolic volume from index admission to 3 months of follow-up.

RESULTS

Adverse remodeling occurred in 23.6% of patients. After adjustment for clinical risk factors, a stroke volume index <29.6 mL/m2, a global longitudinal strain >-7.5%, an infarct size >39.2%, a microvascular obstruction >4.9%, and a myocardial salvage index <36.4 were independently associated with adverse remodeling. The incidence of adverse remodeling increased with the increasing number of high-risk CMR attributes, regardless of LVEF (LVEF ≤ 40%: P = 0.026; 40% < LVEF < 50%: P = 0.001; LVEF ≥ 50%: P < 0.001). The presence of ≥4 high-risk attributes was an independent predictor of LV adverse remodeling (70.0% vs. 16.8%, adjusted OR 9.68, 95 CI% 3.25-28.87, P < 0.001). Furthermore, the number of high-risk CMR attributes had an incremental predictive value over reduced LVEF and baseline clinical risk factors (AUC: 0.81 vs. 0.68; P = 0.002).

CONCLUSIONS

High-risk CMR attributes showed a significant association with adverse remodeling after STEMI across LVEF categories. This imaging-based model provided incremental value for adverse remodeling over traditional clinical factors and LVEF.

Predicting left ventricular remodeling post-MI through coronary physiological measurements based on computational fluid dynamics

Early detection of left ventricular remodeling (LVR) is crucial. While cardiac magnetic resonance (CMR) provides valuable information, it has limitations. Coronary angiography-derived fractional flow reserve (caFFR) and index of microcirculatory resistance (caIMR) offer viable alternatives. 157 patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention were prospectively included. 23.6% of patients showed LVR. Machine learning algorithms constructed three LVR prediction models: Model 1 incorporated clinical and procedural parameters, Model 2 added CMR parameters, and Model 3 included echocardiographic and functional parameters (caFFR and caIMR) with Model 1. The random forest algorithm showed robust performance, achieving AUC of 0.77, 0.84, and 0.85 for Models 1, 2, and 3. SHAP analysis identified top features in Model 2 (infarct size, microvascular obstruction, admission hemoglobin) and Model 3 (current smoking, caFFR, admission hemoglobin). Findings indicate coronary physiology and echocardiographic parameters effectively predict LVR in patients with STEMI, suggesting their potential to replace CMR.

Glycemic Status and Myocardial Strain by Cardiac MRI in Patients With ST-Segment Elevation Myocardial Infarction

BACKGROUND

It is uncertain how various degree of glycemic status affect left ventricular (LV) myocardial strain in ST-segment elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PPCI).

PURPOSE

To investigate the relationship of glycemic status and myocardial strain in STEMI patients.

STUDY TYPE

Prospective cohort study.

POPULATION

282 STEMI patients with cardiac magnetic resonance imaging 5 ± 2 days post-PPCI. Patients were divided into three groups based on the level of glycated hemoglobin A1c (HbA1c) (group 1: HbA1c < 5.7%; group 2: 5.7% ≤ HbA1c < 6.5%; group 3: HbA1c ≥ 6.5%).

FIELD STRENGTH/SEQUENCE

3.0-T; late gadolinium enhancement, balanced steady-state free precession cine sequence, black blood fat-suppressed T2-weighted.

ASSESSMENT

LV function, myocardial strain, and infarct characteristics (infarct size, microvascular obstruction, and intramyocardial hemorrhage) were compared among the three groups by one-way analysis of variance (ANOVA) or Wilcoxon rank sum test. Intraobserver and interobserver reproducibility of LV myocardial strain was evaluated.

STATISTICAL TESTS

ANOVA or Wilcoxon rank sum test, Pearson chi-square or Fisher's exact test, Spearman's correlation analyses and multivariable linear regression analysis. A two-tailed P value <0.05 was considered statistically significant.

RESULTS

Infarct characteristics were similar among the three groups (P = 0.934, P = 0.097, P = 0.533, respectively). Patients with HbA1c ≥ 6.5% had decreased LV myocardial strain compared with HbA1c 5.7%-6.4%, as evidenced by global radial (GRS), global circumferential (GCS), and global longitudinal (GLS) strain. However, no significant differences in myocardial strain were observed between patients with HbA1c 5.7%-6.4% and HbA1c < 5.7% (P = 0.716; P = 0.294; P = 0.883, respectively). After adjustment for confounders, HbA1c as a continuous variable (beta coefficient [β] = -0.676; β = 0.172; β = 0.205, respectively) and HbA1c ≥ 6.5% (β = -3.682; β = 0.552; β = 0.681, respectively) were both independently associated with decreased GRS, GCS, and GLS.

DATA CONCLUSION

Patients with uncontrolled blood glucose (categorized in group HbA1c ≥ 6.5%) had worse myocardial strain. The level of HbA1c appeared to be independently associated with decreased myocardial strain in STEMI patients.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY STAGE: 2.

Direct comparison of coronary microvascular obstruction evaluation using CMR feature tracking and layer-specific speckle tracking echocardiography in STEMI patients

PURPOSE

Layer-specific speckle tissue echocardiography (LS-STE) is a unique technique used to assess coronary microvascular obstruction (CMVO) that may offer more information on the myocardial anatomy of patients with ST-elevation myocardial infarction (STEMI). Cardiovascular magnetic resonance feature tracking (CMR-FT) has also been gaining popularity as a way to evaluate CMVO. The aim of the present study was to directly compare CMVO assessment in STEMI patients using CMR-FT and LS-STE.

PATIENTS AND METHODS

A total of 105 STEMI patients with LS-STE, CMR-FT, and primary percutaneous coronary intervention (PPCI) were included in the study. Longitudinal peak systolic strain (LS), circumferential peak systolic strain (CS), and radial peak systolic strain (RS) were each used to evaluate CMVO using CMR-FT and LS-STE.

RESULTS

Correlation coefficients were 0.56, 0.53, and 0.55 for CMR-FT CS vs. endocardial CS, midcardial CS, and epicardial CS comparisons, respectively, and 0.87, 0.51, and 0.32 for CMR-FT LS vs. endocardial LS, midcardial LS, and epicardial LS comparisons, respectively. Bland-Altman analysis revealed strong inter-modality agreement and little bias in endocardial LS, while the absolute of limited of agreement (LOA) value was 2.28 ± 4.48. The absolutes LOA values were 1.26 ± 11.16, -0.02 ± 12.21, and - 1.3 ± 10.27 for endocardial, midcardial, and epicardial respectively. Intraclass correlation coefficient value of 0.87 showed good reliability in endocardial LS, and moderate reliability with values of 0.71, 0.70, and 0.64 in endocardial, midcardial, and epicardial CS, respectively (all p < 0.001).

CONCLUSIONS

CMR-FT is a viable technique for CMVO evaluation in STEMI patients. Endocardial LS showed good reliability for CMR-FT. STEMI patients can undergo LS-STE to assess the CMVO before PPCI.

Cardiac magnetic resonance for the early prediction of reverse left ventricular remodeling in patients with ST-segment elevation myocardial infarction

OBJECTIVES

To evaluate the changes in cardiac magnetic resonance (CMR) characteristics and investigate the predictors of reverse left ventricular remodeling (r-LVR) in ST-segment elevation myocardial infarction (STEMI) patients.

MATERIALS AND METHODS

Eighty-six STEMI patients (median 56 years) were retrospectively studied. The patients were divided into r-LVR and without r-LVR groups. CMR analysis included LV volume, infarct characteristics, and global and regional myocardial function. The strain and displacement were assessed by CMR-feature tracking. The predictors of r-LVR were analyzed by the logistic regression method.

RESULTS

There were 37 patients in the r-LVR group and 49 patients in the without r-LVR group. At initial CMR, there was no difference in LV volume and global cardiac function between the two groups. However, the infarct zone radial and longitudinal displacements were higher in the r-LVR group (p < 0.05, respectively). At the second CMR, the r-LVR group showed higher LVEF, lower LV volume, and total enhanced mass (all p < 0.05). The infarct zone radial and circumferential strains and radial displacement were higher in the r-LVR group (all p < 0.05). The r-LVR group had better recovery of myocardial injury and function. Of note, microvascular obstruction (MVO) mass (odds ratio: 0.779 (0.613-0.989), p = 0.041) and infarct zone peak longitudinal displacement (PLD) (odds ratio: 1.448 (1.044-2.008), p = 0.026) were independent predictors of r-LVR.

CONCLUSIONS

At initial CMR, there were no differences in global cardiac function between the two groups, but infarct zone displacements were higher in the r-LVR group. The r-LVR group had better recovery of cardiac function. In addition, MVO mass and infarct zone PLD were independent predictors of r-LVR.

CLINICAL RELEVANCE STATEMENT

Our study assessed changes in cardiac structure, function, and tissue characteristics after STEMI by CMR, investigated the best predictors of r-LVR in STEMI patients, and laid the foundation for the development of new parameter-guided treatment strategies for STEMI patients.

KEY POINTS

• At initial CMR, the reverse left ventricular remodeling (r-LVR) group had less myocardial damage and higher infarct zone displacement, but there were no differences in global function between the two groups. • Both groups showed recovery of myocardial injury and cardiac function over time, but the r-LVR group had less enhanced mass and better cardiac function compared to the without r-LVR group at the second CMR. • Microvascular obstruction mass and infarct zone peak longitudinal displacement by cardiac magnetic resonance feature-tracking were significant predictors of r-LVR in STEMI patients.

Four- to seven-year follow-up of pharmacological postconditioning with mangafodipir as an adjunct to primary PCI in ST-segment elevation myocardial infarction

INTRODUCTION

Adverse left ventricular remodelling (AR) develops over time in approximately 30% of patients with a history of coronary artery disease. AR manifests as a structural change in the left ventricle (LV) in terms of increased volumes and reduced left ventricular ejection fraction (LVEF). Manganese dipyridoxyl diphosphate (mangafodipir) has demonstrated interesting cardioprotective features in acute myocardial ischaemia. Pharmacological postconditioning (PP) with mangafodipir as an adjunct to primary percutaneous coronary intervention may possibly reduce the development of AR over time in ST-elevation myocardial infarction (STEMI). The aim of this 4-7-year follow-up study is to investigate the potential benefits of PP with mangafodipir in STEMI patients.

METHOD

Thirteen out of the initial 20 patients that were included in the primary study of Karlsson et al. were followed up between April and June 2017. The study group underwent review of the hospital records, a clinical examination with ECG and blood sample analysis before cardiac magnetic resonance examination of the patient. LVEF, left ventricular diastolic volume, left ventricular end systolic volume, LV mass and myocardial strain in all directions were computed.

RESULTS

The PP group showed a decrease in LV volume, mass and higher LVEF at follow-up (p < 0.05) while the individual response of the placebo group showed features that are seen in AR. Although there was no difference in myocardial strain, measurement for the PP-group was higher in absolute terms.

CONCLUSION

Pharmacological postconditioning with mangafodipir in STEMI demonstrated cardioprotective features compared to the placebo group at follow-up. This article is protected by copyright. All rights reserved.

Delays in first medical contact to primary interventional therapy and left ventricular remodelling in ST-segment elevation myocardial infarction

BACKGROUND

Early reperfusion and early evaluation of adverse cardiovascular events have become important aspects of treatment for ST-segment elevation myocardial infarction post-primary percutaneous coronary intervention (PPCI). However, emergency medical service (EMS) delays always occur, especially in developing countries.

AIMS

The aim of this study was to investigate the impact of EMS delays on short-term predictions of the severity of myocardial injury in STEMI patients after PPCI.

METHODS

A total of 151 STEMI patients who underwent successful PPCI and two postoperative cardiac magnetic resonance (CMR) imaging examinations (1 week and 4 months postoperatively) were retrospectively analysed. CMR cine and late gadolinium enhancement (LGE) images were analysed to evaluate left ventricular (LV) function, LV global longitudinal peak strain (GLS) and scar characteristics. The time from first medical contact to balloon (FMC2B) and door-to-balloon (D2B) time, expressed in minutes, were recorded and compared with the recommended timelines. Unadjusted and multivariable analyses were used to assess the impact of EMS delays on short-term left ventricular remodelling (ALVR).

RESULTS

EMS delays (FMC2B time > 90 min) led to larger infarct size (IS) and microcirculation obstruction (MVO) and poor recovery of the LV ejection fraction and GLS (all p < 0.05). Logistic regression analysis showed that an FMC2B time > 90 min (p = 0.028, OR = 2.661, 95% CI 1.112-6.367) and baseline IS (p = 0.016, OR = 1.079, 95% CI 1.015-1.148) were independent predictors of short-term ALVR.

CONCLUSION

Delays in FMC2B time were strongly associated with short-term ALVR; shorter ischaemic times may improve the cardiac function and prognosis of patients.

Non-Contrast Cine Cardiac Magnetic Resonance Derived-Radiomics for the Prediction of Left Ventricular Adverse Remodeling in Patients With ST-Segment Elevation Myocardial Infarction

OBJECTIVE

To investigate the predictive value of radiomics features based on cardiac magnetic resonance (CMR) cine images for left ventricular adverse remodeling (LVAR) after acute ST-segment elevation myocardial infarction (STEMI).

MATERIALS AND METHODS

We conducted a retrospective, single-center, cohort study involving 244 patients (random-split into 170 and 74 for training and testing, respectively) having an acute STEMI (88.5% males, 57.0 ± 10.3 years of age) who underwent CMR examination at one week and six months after percutaneous coronary intervention. LVAR was defined as a 20% increase in left ventricular end-diastolic volume 6 months after acute STEMI. Radiomics features were extracted from the one-week CMR cine images using the least absolute shrinkage and selection operator regression (LASSO) analysis. The predictive performance of the selected features was evaluated using receiver operating characteristic curve analysis and the area under the curve (AUC).

RESULTS

Nine radiomics features with non-zero coefficients were included in the LASSO regression of the radiomics score (RAD score). Infarct size (odds ratio [OR]: 1.04 (1.00-1.07); P = 0.031) and RAD score (OR: 3.43 (2.34-5.28); P < 0.001) were independent predictors of LVAR. The RAD score predicted LVAR, with an AUC (95% confidence interval [CI]) of 0.82 (0.75-0.89) in the training set and 0.75 (0.62-0.89) in the testing set. Combining the RAD score with infarct size yielded favorable performance in predicting LVAR, with an AUC of 0.84 (0.72-0.95). Moreover, the addition of the RAD score to the left ventricular ejection fraction (LVEF) significantly increased the AUC from 0.68 (0.52-0.84) to 0.82 (0.70-0.93) (P = 0.018), which was also comparable to the prediction provided by the combined microvascular obstruction, infarct size, and LVEF with an AUC of 0.79 (0.65-0.94) (P = 0.727).

CONCLUSION

Radiomics analysis using non-contrast cine CMR can predict LVAR after STEMI independently and incrementally to LVEF and may provide an alternative to traditional CMR parameters.

Impact of myocardial deformation on risk prediction in patients following acute myocardial infarction

Background

Strain analyses derived from cardiovascular magnetic resonance-feature tracking (CMR-FT) provide incremental prognostic benefit in patients sufferring from acute myocardial infarction (AMI). This study aims to evaluate and revalidate previously reported prognostic implications of comprehensive strain analyses in a large independent cohort of patients with ST-elevation myocardial infarction (STEMI).

Methods

Overall, 566 STEMI patients enrolled in the CONDITIONING-LIPSIA trial including pre- and/or postconditioning treatment in addition to conventional percutaneous coronary intervention underwent CMR imaging in median 3 days after primary percutaneous coronary intervention. CMR-based left atrial (LA) reservoir (Es), conduit (Ee), and boosterpump (Ea) strain analyses, as well as left ventricular (LV) global longitudinal strain (GLS), circumferential strain (GCS), and radial strain (GRS) analyses were carried out. Previously identified cutoff values were revalidated for risk stratification. Major adverse cardiac events (MACE) comprising death, reinfarction, and new congestive heart failure were assessed within 12 months after the occurrence of the index event.

Results

Both atrial and ventricular strain values were significantly reduced in patients with MACE (p < 0.01 for all). Predetermined LA and LV strain cutoffs enabled accurate risk assessment. All LA and LV strain values were associated with MACE on univariable regression modeling (p < 0.001 for all), with LA Es emerging as an independent predictor of MACE on multivariable regression modeling (HR 0.92, p = 0.033). Furthermore, LA Es provided an incremental prognostic value above LVEF (a c-index increase from 0.7 to 0.74, p = 0.03).

Conclusion

External validation of CMR-FT-derived LA and LV strain evaluations confirmed the prognostic value of cardiac deformation assessment in STEMI patients. In the present study, LA strain parameters especially enabled further risk stratification and prognostic assessment over and above clinically established risk parameters.

Clinical Trial Registration

ClinicalTrials.gov, identifier NCT02158468.

Imaging Predictors of Left Ventricular Functional Recovery after Reperfusion Therapy of ST-Elevation Myocardial Infarction Assessed by Cardiac Magnetic Resonance

BACKGROUND

Left ventricular global longitudinal strain (LV GLS) is a superior predictor of adverse cardiac events in patients with myocardial infarction and heart failure. We investigated the ability of morphological features of infarcted myocardium to detect acute left ventricular (LV) dysfunction and predict LV functional recovery after three months in patients with acute ST-segment elevation myocardial infarction (STEMI).

METHODS

Sixty-six STEMI patients were included in the C-reactive protein (CRP) apheresis in Acute Myocardial Infarction Study (CAMI-1). LV ejection fraction (LVEF), LV GLS, LV global circumferential strain (LV GCS), infarct size (IS), area-at-risk (AAR), and myocardial salvage index (MSI) were assessed by CMR 5 ± 3 days (baseline) and 12 ± 2 weeks after (follow-up) the diagnosis of first acute STEMI.

RESULTS

Significant changes in myocardial injury parameters were identified after 12 weeks of STEMI diagnosis. IS decreased from 23.59 ± 11.69% at baseline to 18.29 ± 8.32% at follow-up (p < 0.001). AAR and MVO also significantly reduced after 12 weeks. At baseline, there were reasonably moderate correlations between IS and LVEF (r = -0.479, p < 0.001), LV GLS (r = 0.441, p < 0.001) and LV GCS (r = 0.396, p = 0.001) as well as between AAR and LVEF (r = -0.430, p = 0.003), LV GLS (r = 0.501, p < 0.001) and weak with LV GCS (r = 0.342, p = 0.020). At follow-up, only MSI and change in LV GCS over time showed a weak but significant correlation (r = -0.347, p = 0.021). Patients with larger AAR at baseline improved more in LVEF (p = 0.019) and LV GLS (p = 0.020) but not in LV GCS.

CONCLUSION

The CMR tissue characteristics of myocardial injury correlate with the magnitude of LV dysfunction during the acute stage of STEMI. AAR predicts improvement in LVEF and LV GLS, while MSI is a sensitive marker of LV GCS recovery at three months follow-up after STEMI.

Machine learning-based prediction of infarct size in patients with ST-segment elevation myocardial infarction: A multi-center study

BACKGROUND

Cardiac magnetic resonance imaging (CMR) is the gold standard for measuring infarct size (IS). However, this method is expensive and requires a specially trained technologist to administer. We therefore sought to quantify the IS using machine learning (ML) based analysis on clinical features, which is a convenient and cost-effective alternative to CMR.

METHODS AND RESULTS

We included 315 STEMI patients with CMR examined one week after morbidity in final analysis. After feature selection by XGBoost on fifty-six clinical features, we used five ML algorithms (random forest (RF), light gradient boosting decision machine, deep forest, deep neural network, and stacking) to predict IS with 26 (selected by XGBoost with information gain greater than average level of 56 features) and the top 10 features, during which 5-fold cross-validation were used to train and optimize models. We then evaluated the value of actual and ML-IS for the prediction of adverse remodeling. Our finding indicates that MLs outperform the linear regression in predicting IS. Specifically, the RF with five predictors identified by the exhaustive method performed better than linear regression (LR) with 10 indicators (R² of RF: 0.8; LR: 0). The finding also shows that both actual and ML-IS were independently associated with adverse remodeling. ML-IS ≥ 21% was associated with a twofold increase in the risk of LV remodeling (P < 0.01) compared with patients with reference IS (1st tertile).

CONCLUSION

ML-based methods can predict IS with widely available clinical features, which provide a proof-of-concept tool to quantitatively assess acute phase IS.

Recovery and prognostic values of myocardial strain in acute anterior and non-anterior wall myocardial infarction

BACKGROUND

To assess the recovery and prognostic values of myocardial strain using cardiac magnetic resonance (CMR)- feature tracking (FT) in acute anterior and non-anterior wall myocardial infarction.

METHODS

103 reperfused patients after STEMI who underwent CMR at about 4 days (baseline) and 4 months (follow-up) were included, including 48 and 55 patients with anterior wall myocardial infarction (AWMI) and non-anterior wall myocardial infarction(NAWMI). CMR-FT analysis was performed using cine images to measure LV global radial, circumferential, and longitudinal peak strains (GRS, GCS, and GLS, respectively). Infarct size (IS) and microvascular obstruction (MVO) were estimated by late-gadolinium enhancement imaging. The primary clinical endpoint was the occurrence of major adverse cardiac events (MACE) after infarction.

RESULTS

Patients with AWMI had higher IS, higher MVO, lower ejection fraction, and more significantly impaired CMR-FT strain values than patients with NAWMI (all p<0.05). Global strain significantly improved at 4 months (all p<0.01), especial in NAWMI. GLS was an independent predictor (odds ratio = 2.08, 95% confidence interval = 1.032-4.227, p = 0.04] even after adjustment for IS and MVO. The optimal cutoff of GLS was -7.9%, with sensitivity and specificity were 73.3% and 75.0%, respectively. In receiver operating characteristic analysis, IS remained the strongest predictor (area under the curve [AUC] = 0.83, p<0.01), followed by MVO (AUC = 0.81, p<0.01) and GLS (AUC = 0.78, p<0.01).

CONCLUSION

CMR-FT-derived global myocardial strains significantly improved over time, especial in NAWMI. GLS measurement independently predicted the occurrence of medium-term MACE.

Cardiac Magnetic Resonance Imaging in Appraising Myocardial Strain and Biomechanics: A Current Overview

Subclinical alterations in myocardial structure and function occur early during the natural disease course. In contrast, clinically overt signs and symptoms occur during late phases, being associated with worse outcomes. Identification of such subclinical changes is critical for timely diagnosis and accurate management. Hence, implementing cost-effective imaging techniques with accuracy and reproducibility may improve long-term prognosis. A growing body of evidence supports using cardiac magnetic resonance (CMR) to quantify deformation parameters. Tissue-tagging (TT-CMR) and feature-tracking CMR (FT-CMR) can measure longitudinal, circumferential, and radial strains and recent research emphasize their diagnostic and prognostic roles in ischemic heart disease and primary myocardial illnesses. Additionally, these methods can accurately determine LV wringing and functional dynamic geometry parameters, such as LV torsion, twist/untwist, LV sphericity index, and long-axis strain, and several studies have proved their utility in prognostic prediction in various cardiovascular patients. More recently, few yet important studies have suggested the superiority of fast strain-encoded imaging CMR-derived myocardial strain in terms of accuracy and significantly reduced acquisition time, however, more studies need to be carried out to establish its clinical impact. Herein, the current review aims to provide an overview of currently available data regarding the role of CMR in evaluating myocardial strain and biomechanics.

Left Ventricular Adverse Remodeling in Ischemic Heart Disease: Emerging Cardiac Magnetic Resonance Imaging Biomarkers

Post-ischemic left ventricular (LV) remodeling is a biologically complex process involving myocardial structure, LV shape, and function, beginning early after myocardial infarction (MI) and lasting until 1 year. Adverse remodeling is a post-MI maladaptive process that has been associated with long-term poor clinical outcomes. Cardiac Magnetic Resonance (CMR) is the best tool to define adverse remodeling because of its ability to accurately measure LV end-diastolic and end-systolic volumes and their variation over time and to characterize the underlying myocardial changes. Therefore, CMR is the gold standard method to assess in vivo myocardial infarction extension and to detect the presence of microvascular obstruction and intramyocardial hemorrhage, both associated with adverse remodeling. In recent times, new CMR quantitative biomarkers emerged as predictive of post-ischemic adverse remodeling, such as T1 mapping, myocardial strain, and 4D flow. Additionally, CMR T1 mapping imaging may depict infarcted tissue and assess diffuse myocardial fibrosis by using surrogate markers such as extracellular volume fraction, which may predict functional recovery or risk stratification of remodeling. Finally, there is emerging evidence supporting the utility of intracavitary blood flow kinetic energy and hemodynamic features assessed by the 4D flow CMR technique as early predictors of remodeling.

Predictive Value of Cardiac Magnetic Resonance for Left Ventricular Remodeling of Patients with Acute Anterior Myocardial Infarction

Background: Heart failure is a serious complication resulting from left ventricular remodeling (LVR), especially in patients experiencing acute anterior myocardial infarction (AAMI). It is crucial to explore the predictive parameters for LVR following primary percutaneous coronary intervention (PPCI) in patients with AAMI. Methods: A total of 128 AAMI patients who were reperfused successfully by PPCI were enrolled sequentially from June 2018 to December 2019. Cardiovascular magnetic resonance (CMR) was performed at the early stage (<7 days) and after the 6-month follow-up. The patients were divided into LVR and non-LVR groups according to the increase of left ventricular end diastolic volume (LVEDV) measured by the second cardiac magnetic resonance examination ≥20% from baseline. (3) Results: The left ventricular ejection fraction (LVEF), the global longitudinal strain (GLS), the peak circumferential strain in infarcted segments, and the infarct size (IS) remained significantly different in the multivariate logistic regression analysis (all p < 0.05). The area under the receiver operating characteristic curve of Model 1, wherein the GLS was added to the LVEF, was 0.832 (95% CI 0.758−0.907, p < 0.001). The C-statistics for Model 2, which included the infarct-related regional parameters (IS and the peak circumferential strain in infarcted segments)was 0.917 (95% CI 0.870−0.965, p < 0.001). Model 2 was statistically superior to Model 1 in predicting LVR (IDI: 0.190, p = 0.002). (4) Conclusions: Both the global and regional CMR parameters were valuable in predicting LVR in patients with AAMI following the PPCI. The local parameters of the infarct zones were superior to those of the global ones.

Development and validation of a predictive model for adverse left ventricular remodeling in NSTEMI patients after primary percutaneous coronary intervention

Introduction

To develop and validate clinical evaluators that predict adverse left ventricular remodeling (ALVR) in non-ST-elevation myocardial infarction (NSTEMI) patients after primary percutaneous coronary intervention (PCI).

Methods

The retrospective study analyzed the clinical data of 507 NSTEMI patients who were treated with primary PCI from the Affiliated Hospital of Xuzhou Medical University and the Second Affiliated Hospital of Xuzhou Medical University, between January 1, 2019 and September 31, 2021. The training cohort consisted of patients admitted before June 2020 (n = 287), and the remaining patients (n = 220) were assigned to an external validation cohort. The endpoint event was the occurrence of ALVR, which was described as an increase ≥ 20% in left ventricular end-diastolic volume (LVEDV) at 3–4 months follow-up CMR compared with baseline measurements. The occurrence probability of ALVR stemmed from the final model, which embodied independent predictors recommended by logistic regression analysis. The area under the receiver operating characteristic curve (AUC), Calibration plot, Hosmer–Lemeshow method, and decision curve analysis (DCA) were applied to quantify the performance.

Results

Independent predictors for ALVR included age (odds ratio (OR): 1.040; 95% confidence interval (CI): 1.009–1.073), the level of neutrophil to lymphocyte ratio (OR: 4.492; 95% CI: 1.906–10.582), the cardiac microvascular obstruction (OR: 3.416; 95% CI: 1.170–9.970), peak global longitudinal strain (OR: 1.131; 95% CI: 1.026–1.246), infarct size (OR: 1.082; 95% CI: 1.042–1.125) and left ventricular ejection fraction (OR: 0.925; 95% CI: 0.872–0.980), which were screened by regression analysis then merged into the nomogram model. Both internal validation (AUC: 0.805) and external validation (AUC: 0.867) revealed that the prediction model was capable of good discrimination. Calibration plot and Hosmer–Lemeshow method showed high consistency between the probabilities predicted by the nomogram (P = 0.514) and the validation set (P = 0.762) and the probabilities of actual occurrence. DCA corroborated the clinical utility of the nomogram.

Conclusions

In this study, the proposed nomogram model enabled individualized prediction of ALVR in NSTEMI patients after reperfusion and conduced to guide clinical therapeutic schedules.

Comparison of Diagnostic Value Between STE+LDDSE and CMR-FT for Evaluating Coronary Microvascular Obstruction in Post-PCI Patients for STEMI

Background

Coronary microvascular obstruction (CMVO) is closely associated with poor prognosis of ST-segment elevation myocardial infarction (STEMI) patients. However, data showing the comparison between cardiac magnetic resonance feature tracking (CMR-FT) and speckle tracking echocardiography (STE) combined with low-dose dobutamine stress echocardiography (LDDSE) in evaluating CMVO was scarcely available. We aimed to explore and compare the predictive value between CMR-FT and STE+LDDSE in detecting CMVO.

Methods

Sixty-one STEMI patients were executed cardiac magnetic resonance and echocardiography within the first 5–7 days after primary percutaneous coronary intervention (PCI). The myocardial strain analysis was performed in STE, STE+LDDSE, and CMR-FT, and strain parameters included radial strain (RS), circumferential strain (CS), and longitudinal strain (LS). ROC curves were performed to predict infarcted myocardium segments with CMVO.

Results

Finally, 324 infarcted myocardium segments were analyzed, including 100 infarcted segments with CMVO and 224 segments without CMVO by the gold standard assessment of late gadolinium-enhancement cardiac magnetic resonance imaging (LGE-CMR). The results showed that CS was generally superior to RS and LS in identifying CMVO. CS in CMR-FT facilitated the detection of CMVO, with a sensitivity, specificity, and accuracy of 78.00%, 81.25%, and 80.25%, respectively. The sensitivity, specificity, and accuracy of CS in STE combined with LDDSE were better than STE alone (76.00% vs 60.00%, 79.91% vs 64.29%, and 78.70% vs 62.96%, P < 0.05). In addition, CMR-FT is not superior to STE+LDDSE for detection of CMVO (P > 0.05).

Conclusion

Low-dose dobutamine can improve the clinical value of STE for evaluating CMVO in STEMI patients. Compared with CMR-FT, STE+LDDSE might be a better choice for STEMI patients because of its safety, convenience, and low-cost.

A head-to-head comparison of myocardial strain by fast-strain encoding and feature tracking imaging in acute myocardial infarction

Background

Myocardial infarction (MI) is a major cause of heart failure. Left ventricular adverse remodeling is common post-MI. Several studies have demonstrated a correlation between reduced myocardial strain and the development of adverse remodeling. Cardiac magnetic resonance (CMR) with fast-strain encoding (fast-SENC) or feature tracking (FT) enables rapid assessment of myocardial deformation. The aim of this study was to establish a head-to-head comparison of fast-SENC and FT in post-ST-elevated myocardial infarction (STEMI) patients, with clinical 2D speckle tracking echocardiography (2DEcho) as a reference.

Methods

Thirty patients treated with primary percutaneous coronary intervention for STEMI were investigated. All participants underwent CMR examination with late gadolinium enhancement, cine-loop steady-state free precession, and fast-SENC imaging using a 1.5T scanner as well as a 2DEcho. Global longitudinal strain (GLS), segmental longitudinal strain (SLS), global circumferential strain (GCS), and segmental circumferential strain (SCS) were assessed along with the MI scar extent.

Results

The GCS measurements from fast-SENC and FT were nearly identical: the mean difference was 0.01 (2.5)% (95% CI - 0.92 to 0.95). For GLS, fast-SENC values were higher than FT, with a mean difference of 1.8 (1.4)% (95% CI 1.31-2.35). Tests of significance for GLS did not show any differences between the MR methods and 2DEcho. Average strain in the infarct-related artery (IRA) segments compared to the remote myocardium was significantly lower for the left anterior descending artery and right coronary artery culprits but not for the left circumflex artery culprits. Fast-SENC displayed a higher area under the curve for detecting infarcted segments than FT for both SCS and SLS.

Conclusion

GLS and GCS did not significantly differ between fast-SENC and FT. Both showed acceptable agreement with 2DEcho for longitudinal strain. Segments perfused by the IRA showed significantly reduced strain values compared to the remote myocardium. Fast-SENC presented a higher sensitivity and specificity for detecting infarcted segments than FT.

Protective Value of Aspirin Loading Dose on Left Ventricular Remodeling After ST-Elevation Myocardial Infarction

AIMS

Left ventricular (LV) remodeling after ST-elevation myocardial infarction (STEMI) is a complex process, defined as changes of LV volumes over time. CMR feature tracking analysis (CMR-FT) offers an accurate quantitative assessment of LV wall deformation and myocardial contractile function. This study aimed to evaluate the role of myocardial strain parameters in predicting LV remodeling and to investigate the effect of Aspirin (ASA) dose before primary coronary angioplasty (pPCI) on myocardial injury and early LV remodeling.

METHODS AND RESULTS

Seventy-eight patients undergoing CMR, within 9 days from symptom onset and after 6 months, were enrolled in this cohort retrospective study. We divided the study population into three groups based on a revised Bullock's classification and we evaluated the role of baseline CMR features in predicting early LV remodeling. Regarding CMR strain analysis, worse global circumferential and longitudinal strain (GCS and GLS) values were associated with adverse LV remodeling. Patients were also divided based on pre-pPCI ASA dosage. Significant differences were detected in patients receiving ASA 500 mg dose before pPCI, which showed lower infarct size extent and better strain values compared to those treated with ASA 250 mg. The stepwise multivariate logistic regression analysis, adjusted for covariates, indicated that a 500 mg ASA dose remained an inverse independent predictor of early adverse LV remodeling.

CONCLUSION

GCS and GLS have high specificity to detect early LV adverse remodeling. We first reported a protective effect of ASA loading dose of 500 mg before pPCI on LV myocardial damage and in reducing early LV adverse remodeling.

Effect of Mitral Regurgitation on Left Ventricular Deformation in Myocardial Infarction Patients: Evaluation by Cardiac Magnetic Resonance Imaging

BACKGROUND

Mitral regurgitation (MR) is a comorbidity of myocardial infarction (MI), which may promote the incidence of adverse cardiovascular clinical events. However, it is not yet completely understood how MR in MI patients is associated with impaired myocardial deformation.

PURPOSE

To determine the damaging myocardium effects of MR in MI patients in terms of the global peak strain (PS) and left ventricular (LV) function, and evaluate the independent risk factors impacting LV deformation after MI.

STUDY TYPE

Retrospective.

POPULATION

One hundred eighty-six MI patients (17.7% female) and 84 normal control subjects (27.4% female).

FIELD STRENGTH/SEQUENCE

3.0T; late gadolinium enhancement sequence, balanced steady-state free precession.

ASSESSMENT

LV function and LV global PS (global radial peak strain [GRPS]; global circumferential peak strain [GCPS]; and global longitudinal peak strain [GLPS]) were compared among normal controls, MI without MR (MR-) and MI with MR (MR+, mild, moderate, severe) patients.

STATISTICAL TESTS

One-way analysis of variance (ANOVA) test, Mann-Whitney U test, Kruskal-Wallis test, and multiple linear regressions were used. A P value <0.05 indicated statistically significant difference (two-tailed).

RESULTS

The MI (MR+) patients showed significantly lower LV global PS than both MI (MR-) and control groups in three directions (GRPS 16.66 ± 7.43%; GCPS -11.27 ± 4.27%; GLPS -7.75 ± 3.44%), and significantly higher LV end-systolic (128.85 [87.91, 188.01] mL) and end-diastolic volumes (210.29 [164.07, 264.00] mL) and significantly lower LV ejection fraction (38.23 ± 13.02%). Multiple regression analysis demonstrated that MR was independently associated with LV GCPS (β = -0.268) and GLPS (β = -0.320). LV infarct size was an independent indicator of LV GRPS (β = -0.215) and GCPS (β = -0.222). LV end-diastolic volume was an independent indicator of LV GRPS (β = -0.518), GCPS (β = -0.503), and GLPS (β = -0.331).

DATA CONCLUSION

MR may further exacerbate the reduction of LV global peak strains and function. The MR, infarct size, and LV end-diastolic volume can be used as independent association indicators for LV global PS in MI (MR+) patients.

LEVEL OF EVIDENCE

4 Technical Efficacy Stage: 2 TOC Category: Chest.

Quantification of Myocardial Deformation in Patients with Takayasu Arteritis by Cardiovascular Magnetic Resonance Feature Tracking Imaging

BACKGROUND

Cardiac involvement is one of the main causes of morbidity and mortality in patients with Takayasu arteritis (TA). Early detection and intervention of cardiac damage may be helpful to reduce the mortality of TA. Magnetic resonance (MR) imaging (MRI)-derived feature tracking (FT) is an effective quantitative method to assess myocardial deformation which may reflect early changes of cardiac function.

PURPOSE

To explore the utility of MR-FT as a method to detect cardiac damage in TA patients.

STUDY TYPE

Retrospective.

POPULATION

Fifty-seven TA patients who had undergone clinically indicated MRI and 57 healthy controls.

FIELD STRENGTH/SEQUENCES

Balanced steady-state free precession rest cine and 2D phase-sensitive inversion recovery breath-hold segmented gradient echo late gadolinium enhancement (LGE) sequences at 3.0 T.

ASSESSMENT

Based on LGE images, TA patients were divided into two subgroups, LGE (+) subgroup (N = 12) and LGE (-) subgroup (N = 45). In addition, patients were further subdivided into impaired (N = 26) and preserved left ventricle ejection fraction (LVEF) subgroups (N = 31). FT-derived deformation indices, including left ventricular (LV) global longitudinal strain (GLS), were measured by commercial software.

STATISTICAL TESTS

Mann-Whitney U-test, Kruskal-Wallis test followed by Dunn-Bonferroni post hoc method, and receiver operating characteristic curve analysis were conducted. A P-value of <0.05 was considered statistically significant.

RESULTS

GLS was significantly worse in TA than in controls (median [interquartile range, IQR]: TA -10.0 [-7.5 to 12.4] vs. controls -12.7 [-11.8 to 14.7]). Moreover, TA patients with LGE (+) had significantly poorer GLS than those with LGE (-) (median [IQR]: LGE (+) -6.8 [-4.0 to 8.1] vs. LGE (-) -10.7 [-8.5 to 12.9]). The reduced LVEF subgroup had significantly greater cardiac dysfunction as measured by MR-FT than the preserved LVEF subgroup (GLS median [IQR]: reduced LVEF -7.9 [-6.2 to 11.4] vs. preserved LVEF -10.8 [-8.6 to 13.5]).

DATA CONCLUSION

Myocardial deformation impairment was found in the majority of TA patients. MR-FT imaging may be helpful in the early diagnosis and management of TA patients.

LEVEL OF EVIDENCE

4 TECHNICAL EFFICACY STAGE: 5.

Quantification of Myocardial Deformation Applying CMR-Feature-Tracking-All About the Left Ventricle?

Purpose of Review

Cardiac magnetic resonance-feature-tracking (CMR-FT)-based deformation analyses are key tools of cardiovascular imaging and applications in heart failure (HF) diagnostics are expanding. In this review, we outline the current range of application with diagnostic and prognostic implications and provide perspectives on future trends of this technique.

Recent Findings

By applying CMR-FT in different cardiovascular diseases, increasing evidence proves CMR-FT-derived parameters as powerful diagnostic and prognostic imaging biomarkers within the HF continuum partly outperforming traditional clinical values like left ventricular ejection fraction. Importantly, HF diagnostics and deformation analyses by CMR-FT are feasible far beyond sole left ventricular performance evaluation underlining the holistic nature and accuracy of this imaging approach.

Summary

As an established and continuously evolving technique with strong prognostic implications, CMR-FT deformation analyses enable comprehensive cardiac performance quantification of all cardiac chambers.

Targeting 5-HT2B Receptor Signaling Prevents Border Zone Expansion and Improves Microstructural Remodeling After Myocardial Infarction

BACKGROUND

Myocardial infarction (MI) induces an intense injury response that ultimately generates a collagen-dominated scar. Although required to prevent ventricular rupture, the fibrotic process is often sustained in a manner detrimental to optimal recovery. Cardiac myofibroblasts are the cells tasked with depositing and remodeling collagen and are a prime target to limit the fibrotic process after MI. Serotonin 2B receptor (5-HT2B) signaling has been shown to be harmful in a variety of cardiopulmonary pathologies and could play an important role in mediating scar formation after MI.

METHODS

We used 2 pharmacological antagonists to explore the effect of 5-HT2B inhibition on outcomes after MI and characterized the histological and microstructural changes involved in tissue remodeling. Inducible 5-HT2B ablation driven by Tcf21MCM and PostnMCM was used to evaluate resident cardiac fibroblast- and myofibroblast-specific contributions of 5-HT2B, respectively. RNA sequencing was used to motivate subsequent in vitro analyses to explore cardiac fibroblast phenotype.

RESULTS

5-HT2B antagonism preserved cardiac structure and function by facilitating a less fibrotic scar, indicated by decreased scar thickness and decreased border zone area. 5-HT2B antagonism resulted in collagen fiber redistribution to thinner collagen fibers that were more anisotropic, enhancing left ventricular contractility, whereas fibrotic tissue stiffness was decreased, limiting the hypertrophic response of uninjured cardiomyocytes. Using a tamoxifen-inducible Cre, we ablated 5-HT2B from Tcf21-lineage resident cardiac fibroblasts and saw similar improvements to the pharmacological approach. Tamoxifen-inducible Cre-mediated ablation of 5-HT2B after onset of injury in Postn-lineage myofibroblasts also improved cardiac outcomes. RNA sequencing and subsequent in vitro analyses corroborate a decrease in fibroblast proliferation, migration, and remodeling capabilities through alterations in Dnajb4 expression and Src phosphorylation.

CONCLUSIONS

Together, our findings illustrate that 5-HT2B expression in either cardiac fibroblasts or activated myofibroblasts directly contributes to excessive scar formation, resulting in adverse remodeling and impaired cardiac function after MI.