Cardiac Magnetic Resonance Evaluation of Left Ventricular Myocardial Strain in Pulmonary Hypertension

Biventricular Dysfunction and Ventricular Interdependence in Patients With Pulmonary Hypertension: A 3.0-T Cardiac MRI Feature Tracking Study

BACKGROUND

Pulmonary hypertension (PH) results in right ventricular (RV) dysfunction, subsequently leading to left ventricular (LV) impairment. The mechanism underlying ventricular interdependence is largely uninvestigated.

PURPOSE

To explore the biventricular dysfunction and the ventricular interdependence in PH patients.

STUDY TYPE

Retrospective.

POPULATION

One hundred and seven PH patients (mean pulmonary artery pressure >20 mmHg) and 72 age- and sex-matched controls with cardiac magnetic resonance imaging (MRI) studies.

FIELD STRENGTH/SEQUENCE

3.0 T/balanced steady-state free precession sequence.

ASSESSMENT

LV and RV ejection fractions (EF) and RV and LV radial, circumferential, and longitudinal strains were assessed using commercial software. Strains were compared between controls, PH patients with preserved RVEF (RVEF ≥40%, N = 48), and PH patients with reduced RVEF (RVEF <40%, N = 59).

STATISTICAL TESTS

Chi-squared tests or Fisher's exact test, t tests or Mann-Whitney U test, one-way ANOVA with Bonferroni's post hoc correction or Kruskal-Wallis test, Pearson or Spearman correlation, and multivariable linear regression analysis. A two-tailed P < 0.05 was deemed statistically significant.

RESULTS

RV strain decreased sequentially from controls, through PH with preserved RVEF, to PH with reduced RVEF. PH patients with reduced RVEF had significantly lower LV strain, especially septal strain, and LV peak diastolic strain rate compared with both controls and PH patients with preserved RVEF. Multivariable analyses showed that RVEF was independently correlated with LV strain; furthermore, independent of RVEF, RV strain was significantly correlated with LV strain (LVGRS: β = 0.416; LVGCS: β = -0.371; LVGLS: β = 0.283).

DATA CONCLUSION

Subclinical impairment of RV function was found in PH with preserved RVEF. LV strain was impaired when RV was dysfunctional, which was associated with worsening RV strain. Therefore, while focusing on improving RV function, LV dysfunction in PH patients should also be monitored and treated early in order to slow the progression of the disease.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 3.

Biventricular intraventricular mechanical and electrical dyssynchrony in pulmonary arterial hypertension

Background

Pulmonary arterial hypertension (PAH) leads to myocardial remodeling, manifesting as mechanical dyssynchrony (M-dys) and electrical dyssynchrony (E-dys), in both right (RV) and left ventricles (LV). However, the impacts of layer-specific intraventricular M-dys on biventricular functions and its association with E-dys in PAH remain unclear.

Methods

Seventy-nine newly diagnosed patients with PAH undergoing cardiac magnetic resonance scanning were consecutively recruited between January 2011 and December 2017. The biventricular volumetric and layer-specific intraventricular M-dys were analyzed. The QRS duration z-scores were calculated after adjusting for age and sex.

Results

77.22 % of patients were female (mean age 30.30 ± 9.79 years; median follow-up 5.53 years). Further, 29 (36.71 %) patients succumbed to all-cause mortality by the end of the study. At the baseline, LV layer-specific intraventricular M-dys had apparent transmural gradients compared with RV in the radial and circumferential directions. However, deceased patients lost the transmural gradients. The LV longitudinal strain rate time to late diastolic peak in the myocardial region (LVmyoLSRTTLDPintra) predicted long-term survival. The Kaplan-Meier curve revealed that patients with PAH with LVmyoLSRTTLDPintra <20.01 milliseconds had a worse prognosis. Larger right ventricle (RV) intraventricular M-dys resulted in worse RV ejection fraction. However, larger LV intraventricular M-dys in the late diastolic phase indicated remarkable exercise capacity and higher LV stroke volume index. E-dys and intraventricular M-dys had no direct correlations.

Conclusions

The layer-specific intraventricular M-dys had varying impacts on biventricular functions in PAH. PAH patients with LVmyoLSRTTLDPintra <20.01 milliseconds had a worse prognosis. LV intraventricular M-dys in the late diastolic phase needs more attention to precisely evaluate LV function.

The Prognostic Value of One-Year Changes in Biventricular Mechanics for Three-Year Survival in Patients with Precapillary Pulmonary Hypertension: A Cardiovascular Magnetic Resonance Feature Tracking Study

Background and Objectives: The management of patients with pulmonary hypertension (PH) poses a considerable challenge. While baseline cardiac magnetic resonance imaging (cMRI) indices are recognized for survival prognosis in PH, the prognostic value of one-year changes in biventricular mechanics, especially as assessed using feature tracking (FT) technology, remains underexplored. This study aims to assess the predictive value of one-year change in cMRI-derived biventricular function and mechanics parameters, along with N-terminal pro-brain natriuretic peptide (NT-proBNP) levels and six-minute walking test (6MWT) results for three-year mortality in precapillary PH patients. Materials and Methods: In this retrospective study, 36 patients diagnosed with precapillary pulmonary hypertension (mPAP 55.0 [46.3-70.5] mmHg, pulmonary capillary wedge pressure 10.0 [6.0-11.0] mmHg) were included. Baseline and one-year follow-up cMRI assessments, clinical data, and NT-proBNP levels were analyzed. FT technology was utilized to assess biventricular strain parameters. Patients were categorized into survival and non-survival groups based on three-year outcomes. Statistical analyses, including univariate logistic regression and Cox regression, were performed to identify predictive parameters. Results: The observed three-year survival rate was 83.3%. Baseline right ventricle (RV) ejection fraction (EF) was significantly higher in the survival group compared to non-survivors (41.0 [33.75-47.25]% vs. 28.0 [23.5-36.3]%, p = 0.044), and values of ≤32.5% were linked to a 20-fold increase in mortality risk. RV septum longitudinal strain (LS) and RV global LS exhibited significant improvement over a one-year period in the survival group compared to the non-survival group (-1.2 [-6.4-1.6]% vs. 4.9 [1.5-6.7]%, p = 0.038 and -3.1 [-9.1-2.6]% vs. 4.5 [-2.1-8.5]%, p = 0.048, respectively). Declines in RV septum LS by ≥2.95% and in RV GLS by ≥3.60% were associated with a 25-fold and 8-fold increase in mortality risk, respectively. Conclusions: The decrease in right ventricular septal and global longitudinal strain over a one-year period demonstrates a significant predictive value and an association with an increased three-year mortality risk in patients with precapillary PH.

Myocardial strain parameters in pulmonary hypertension are determined by changes in volumetric function rather than by hemodynamic alterations

PURPOSE

To investigate associations of cardiac magnetic resonance feature-tracking-derived left (LV) and right ventricular (RV) global myocardial peak strains and strain rates with volumetric function and hemodynamic parameters to identify the major determinants of myocardial strain alterations in pulmonary hypertension (PH).

METHODS

Sixty-seven patients with PH or at risk of developing PH underwent right heart catheterization (RHC) and cine realtime imaging at 3 T. RHC parameters included mean pulmonary arterial pressure (mPAP), which was used for the diagnosis of PH. LV and RV volumetric function and feature-tracking-derived global radial, circumferential, and longitudinal (GLS) peak strains, together with their strain rates, were evaluated from cine images using routine software. Furthermore, myocardial strain parameters of 24 healthy subjects were evaluated as controls. Means were compared by t-test; relationships between parameters were investigated by correlation and regression analysis.

RESULTS

Compared to controls, RV-GLS, all RV systolic strain rates and the LV systolic longitudinal strain rate showed lower magnitudes in PH (RV-GLS: -21 ± 4% vs. -16 ± 5%, p < 0.0001); the strongest univariate correlate to mPAP was the RV-GLS (r = 0.59). All LV and RV strain parameters yielded stronger correlations with their respective ejection fractions. In bi-linear models using mPAP and ejection fraction as predictors, mPAP remained significant only for diastolic LV radial and circumferential strain rates.

CONCLUSION

Impairment of myocardial strains is more strongly associated with alterations in LV and RV volumetric function parameters than elevated mPAP, therefore limiting diagnostic information of myocardial strain parameters in PH.

Assessment of Right Ventricular Function-a State of the Art

PURPOSE OF REVIEW

The right ventricle (RV) has a complex geometry and physiology which is distinct from the left. RV dysfunction and failure can be the aftermath of volume- and/or pressure-loading conditions, as well as myocardial and pericardial diseases.

RECENT FINDINGS

Echocardiography, magnetic resonance imaging and right heart catheterisation can assess RV function by using several qualitative and quantitative parameters. In pulmonary hypertension (PH) in particular, RV function can be impaired and is related to survival. An accurate assessment of RV function is crucial for the early diagnosis and management of these patients. This review focuses on the different modalities and indices used for the evaluation of RV function with an emphasis on PH.

The heart of the matter: Right heart imaging indicators for treatment escalation in pulmonary arterial hypertension

Right heart (RH) structure and function are major determinants of symptoms and prognosis in pulmonary arterial hypertension (PAH). RH imaging provides detailed information, but evidence and guidelines on the use of RH imaging in treatment decisions are limited. We conducted a Delphi study to gather expert opinion on the role of RH imaging in decision-making for treatment escalation in PAH. A panel of 17 physicians with expertise in PAH and RH imaging used three surveys in a modified Delphi process to reach consensus on the role of RH imaging in PAH. Survey 1 used open-ended questions to gather information. Survey 2 contained Likert scale and other questions intended to identify consensus on topics identified in Survey 1. Survey 3 contained Likert scale questions derived from Survey 2 and summary information on the results of Survey 2. The Delphi panel reached consensus that RH imaging is likely to improve the current risk stratification algorithms and help differentiate risk levels in patients at intermediate risk. Tricuspid annular plane systolic excursion, right ventricular fractional area change, right atrial area, tricuspid regurgitation, inferior venae cavae diameter, and pericardial effusion should be part of routine echocardiography in PAH. Cardiac magnetic resonance imaging is valuable but limited by cost and access. A pattern of abnormal RH imaging results should prompt consideration of hemodynamic evaluation and possible treatment escalation. RH imaging is an important tool for decisions about treatment escalation in PAH, but systematically collected evidence is needed to clarify its role.

Left ventricular strain in patients with Takayasu arteritis with preserved ejection fraction: an analysis using cardiac magnetic resonance imaging feature tracking

Background

The alteration of myocardial strain in patients with Takayasu arteritis (TAK) remains unclear. This study aimed to evaluate left ventricular (LV) stain in patients with TAK and preserved left ventricular ejection fraction (pLVEF) using cardiac magnetic resonance imaging feature tracking (CMR-FT) to analyze risk factors for impaired LV strain and to compare the baseline difference of LV strain between patients with reduced and nonreduced LVEF at 6-month follow-up.

Methods

In all, 51 patients with TAK and 30 healthy controls were prospectively enrolled. All participants underwent multiple short- and long-axis cine scans with true fast imaging with steady-state precession sequence. In this observational study, LV global and regional longitudinal, circumferential, and radial strain and their strain rates were analyzed with FT on cine images. The relationship between LV strain and clinical data was explored. The baseline LV strain between patients with TAK and reduced and nonreduced LVEF was compared using transthoracic echocardiography (TTE) at the 6-month follow-up.

Results

Patients with TAK with pLVEF showed a decline in baseline global longitudinal peak strain (GLS) [TAK (-13.35%±3.11%) vs. controls (-14.77%±1.74%), P=0.021] and circumferential peak strain (GCS) [TAK (-21.46%±2.66%) vs. controls (-22.75%±2.57%), P=0.027] in comparison with normal controls. The longitudinal peak strain (LPS) in the apical (P=0.003) and midventricular regions (P=0.027) and the circumferential peak strain (CPS) in the basal (P=0.021) and midventricular regions (P=0.008) also decreased in patients with TAK. Patients with pulmonary hypertension (PH) or myocardial late gadolinium enhancement (LGE) showed a greater reduction in strain compared with those without PH or LGE. GLS showed a negative association with erythrocyte sedimentation rate (ESR), while GCS showed a positive association with disease duration. In the 30 patients who were followed up, the baseline global and apical circumferential diastolic peak strain rates (DPSR) in patients with reduced LVEF were higher than those in patients without reduced LVEF.

Conclusions

In patients with TAK and pLVEF, CMR-FT indicated that both global and segmental myocardial strain decreased. PH, male gender, long disease duration, elevated ESR, and myocardial LGE were associated with declined LV strain. Baseline increased circumferential DPSR may be associated with the decline in LVEF during follow-up.

Apply pressure-strain loop to quantify myocardial work in pulmonary hypertension: A prospective cohort study

Objectives

Pressure-strain loop (PSL) is a novel method to quantify myocardial work in many cardiovascular diseases. To investigate the value of myocardial work parameters derived from PSL for evaluating cardiac function and clinical prognosis in patients with pulmonary hypertension (PH).

Methods

A total of 52 patients with PH and 27 healthy controls were enrolled in this prospective study. PSLs determined by echocardiography were used to calculate global work index (GWI) of left ventricle (LV) and right ventricle (RV). Global constructive work (GCW) comprised the sum of myocardial work performed during shortening in systole and during lengthening in isovolumic relaxation. Global wasted work (GWW) comprised the sum of myocardial work performed during lengthening in systole and during shortening in isovolumic relaxation. Global work efficiency (GWE) was defined as GCW/(GCW + GWW).

Results

LVGWW, RVGWI, RVGCW and RVGWW were significantly higher in patients than controls (all P < 0.001). LVGWE, LVGWI, LVGCW, and RVGWE were lower in patients than controls (all P < 0.01). Myocardial work parameters correlated well with clinical and other conventional echocardiographic assessments (all P < 0.05). In binary logistic regression analysis, the combination of RVGWE and estimation of pulmonary arterial systolic pressure (ePASP) was the best model to predict clinical outcomes (OR = 0.803, P = 0.002 and OR = 1.052, P = 0.015, respectively). Receiver operating characteristic curv demonstrated the combination of RVGWE and ePASP was the best predictor of adverse events with 100% sensitivity and 76.3% specificity (AUC = 0.910, P < 0.001).

Conclusion

Myocardial work parameters derived from PSL are emerging markers of cardiac function. And the combination of RVGWE and ePASP is a useful predictor of clinical outcome in PH patients.

The Balance between the Left and Right Ventricular Deformation Evaluated by Speckle Tracking Echocardiography Is a Great Predictor of the Major Adverse Cardiac Event in Patients with Pulmonary Hypertension

Cardiovascular failure is one of the most relevant causes of death in pulmonary hypertension (PH). With progressive increases of right ventricular (RV) afterload in PH patients, both RV and left ventricular (LV) function impair and RV–LV dyssynchrony develop in parallel. We aimed to analyze the balance between the left and right ventricular deformation to assess the outcome of patients with pulmonary hypertension by means of speckle tracking echocardiography. In this prospective study, 54 patients with invasively diagnosed pulmonary hypertension, and 26 healthy volunteers were included and underwent a broad panel of noninvasive assessment including 2D-echocardiography, 2D speckle tracking, 6-minute walking test and BNP. Patients were followed up for 338.7 ± 131.1 (range 60 to 572) days. There were significant differences in |LVGLS/RVFLS-1| and |LASc/RASc-1| between PH patients and the control group. During the follow up, 13 patients experienced MACEs, which included 7 patients with cardiac death and 6 patients with re-admitted hospital due to right ventricular dysfunction. In the multivariate Cox model analysis, |LVGLS/RVFLS-1| remained independent prognosis of markers (HR = 4.03). Our study findings show that |LVGLS/RVFLS-1| is of high clinical and prognostic relevance in pulmonary hypertension patients and reveal the importance of the balance between the left and right ventricular deformation.

Myocardial Strain Evaluation with Cardiovascular MRI: Physics, Principles, and Clinical Applications

Myocardial strain is a measure of myocardial deformation, which is a more sensitive imaging biomarker of myocardial disease than the commonly used ventricular ejection fraction. Although myocardial strain is commonly evaluated by using speckle-tracking echocardiography, cardiovascular MRI (CMR) is increasingly performed for this purpose. The most common CMR technique is feature tracking (FT), which involves postprocessing of routinely acquired cine MR images. Other CMR strain techniques require dedicated sequences, including myocardial tagging, strain-encoded imaging, displacement encoding with stimulated echoes, and tissue phase mapping. The complex systolic motion of the heart can be resolved into longitudinal strain, circumferential strain, radial strain, and torsion. Myocardial strain metrics include strain, strain rate, displacement, velocity, torsion, and torsion rate. Wide variability exists in the reference ranges for strain dependent on the imaging technique, analysis software, operator, patient demographics, and hemodynamic factors. In anticancer therapy cardiotoxicity, CMR myocardial strain can help identify left ventricular dysfunction before the decline of ejection fraction. CMR myocardial strain is also valuable for identifying patients with left ventricle dyssynchrony who will benefit from cardiac resynchronization therapy. CMR myocardial strain is also useful in ischemic heart disease, cardiomyopathies, pulmonary hypertension, and congenital heart disease. The authors review the physics, principles, and clinical applications of CMR strain techniques. Online supplemental material is available for this article. ^©RSNA, 2022.

Biventricular Myocardial Strain Analysis in Patients with Pulmonary Arterial Hypertension Using Cardiac Magnetic Resonance Tissue-Tracking Technology

To evaluate both left and right ventricular (LV and RV) function in patients with pulmonary arterial hypertension (PAH) using cardiac magnetic resonance tissue-tracking (CMR-TT) technology and explore its clinical value. Methods: A total of 79 participants (including 47 patients with PAH and 32 healthy controls) underwent cardiac magnetic resonance imaging (CMRI) with a short-axis balanced steady-state free precession (SSFP) sequence. The biventricular cardiac function parameters and strain parameters were obtained by postprocessing with CVI42 software. A comparative analysis was performed between the LV and RV strain parameters in all PAH patients and in PAH patients with reduced or preserved cardiac function. Results: The results showed preferable repeatability of CMR-TT in analyzing the global radial strain (GRS), circumferential strain (GCS), and longitudinal strain (GLS) of the left and right ventricles in the PAH group. The GRS, GCS, and GLS of the left and right ventricles except for LV GRS (LVGRS) of PAH patients were significantly lower than those of healthy controls (p < 0.05 for all). The GRS and GCS of the left and right ventricles showed a moderate correlation in the PAH group (r = 0.323, p = 0.02; r = 0.301, p = 0.04, respectively). PAH patients with preserved RV function (n = 9) showed significantly decreased global and segmental RS, CS, and LS of the right ventricles than healthy controls (p < 0.05 for all), except for basal RVGCS (RVGCS-b, p = 0.996). Only the LVGLS was significantly different between the PAH patients with preserved LV function (n = 32) and the healthy controls (−14.23 ± 3.01% vs. −16.79 ± 2.86%, p < 0.01). Conclusions: As a nonradioactive and noninvasive technique, CMR-TT has preferable feasibility and repeatability in quantitatively evaluating LV and RV strain parameters in PAH patients and can be used to effectively detect early biventricular myocardial damage in patients with PAH.

MRI Feature Tracking Strain in Pulmonary Hypertension: Utility of Combined Left Atrial Volumetric and Deformation Assessment in Distinguishing Post- From Pre-capillary Physiology

Aims

Pulmonary hypertension (PH) is dichotomized into pre- and post-capillary physiology by invasive catheterization. Imaging, particularly strain assessment, may aid in classification and be helpful with ambiguous hemodynamics. We sought to define cardiac MRI (CMR) feature tracking biatrial peak reservoir and biventricular peak systolic strain in pre- and post-capillary PH and examine the performance of peak left atrial strain in distinguishing the 2 groups compared to TTE.

Methods and Results

Retrospective cross-sectional study from 1 Jan 2015 to 31 Dec 2020; 48 patients (22 pre- and 26 post-capillary) were included with contemporaneous TTE, CMR and catheterization. Mean pulmonary artery pressures were higher in the pre-capillary cohort (55 ± 14 vs. 42 ± 9 mmHg; p &lt; 0.001) as was pulmonary vascular resistance (median 11.7 vs. 3.7 WU; p &lt; 0.001). Post-capillary patients had significantly larger left atria (60 ± 22 vs. 25 ± 9 ml/m2; p &lt; 0.001). There was no difference in right atrial volumes between groups (60 ± 21 vs. 61 ± 29 ml/m2; p = 0.694), however peak RA strain was lower in post-capillary PH patients (8.9 ± 5.5 vs. 18.8 ± 7.0%; p &lt; 0.001). In the post-capillary group, there was commensurately severe peak strain impairment in both atria (LA strain 9.0 ± 5.8%, RA strain 8.9 ± 5.5%). CMR LAVi and peak LA strain had a multivariate AUC of 0.98 (95% CI 0.89–1.00; p &lt; 0.001) for post-capillary PH diagnosis which was superior to TTE.

Conclusion

CMR volumetric and deformation assessment of the left atrium can highly accurately distinguish post- from pre-capillary PH.

State-of-the-art myocardial strain by CMR feature tracking: clinical applications and future perspectives

Based on conventional cine sequences of cardiac magnetic resonance (CMR), feature tracking (FT) is an emerging tissue tracking technique that evaluates myocardial motion and deformation quantitatively by strain, strain rate, torsion, and dyssynchrony. It has been widely accepted in modern literature that strain analysis can offer incremental information in addition to classic global and segmental functional analysis. Furthermore, CMR-FT facilitates measurement of all cardiac chambers, including the relatively thin-walled atria and the right ventricle, which has been a difficult measurement to obtain with the reference standard technique of myocardial tagging. CMR-FT objectively quantifies cardiovascular impairment and characterizes myocardial function in a novel way through direct assessment of myocardial fiber deformation. The purpose of this review is to discuss the current status of clinical applications of myocardial strain by CMR-FT in a variety of cardiovascular diseases. KEY POINTS: • CMR-FT is of great value for differential diagnosis and provides incremental value for evaluating the progression and severity of diseases. • CMR-FT guides the early diagnosis of various cardiovascular diseases and provides the possibility for the early detection of myocardial impairment and additional information regarding subclinical cardiac abnormalities. • Direct assessment of myocardial fiber deformation using CMR-FT has the potential to provide prognostic information incremental to common clinical and CMR risk factors.

Radiomics side experiments and DAFIT approach in identifying pulmonary hypertension using Cardiac MRI derived radiomics based machine learning models

Side experiments are performed on radiomics models to improve their reproducibility. We measure the impact of myocardial masks, radiomic side experiments and data augmentation for information transfer (DAFIT) approach to differentiate patients with and without pulmonary hypertension (PH) using cardiac MRI (CMRI) derived radiomics. Feature extraction was performed from the left ventricle (LV) and right ventricle (RV) myocardial masks using CMRI in 82 patients (42 PH and 40 controls). Various side study experiments were evaluated: Original data without and with intraclass correlation (ICC) feature-filtering and DAFIT approach (without and with ICC feature-filtering). Multiple machine learning and feature selection strategies were evaluated. Primary analysis included all PH patients with subgroup analysis including PH patients with preserved LVEF (≥ 50%). For both primary and subgroup analysis, DAFIT approach without feature-filtering was the highest performer (AUC 0.957-0.958). ICC approaches showed poor performance compared to DAFIT approach. The performance of combined LV and RV masks was superior to individual masks alone. There was variation in top performing models across all approaches (AUC 0.862-0.958). DAFIT approach with features from combined LV and RV masks provide superior performance with poor performance of feature filtering approaches. Model performance varies based upon the feature selection and model combination.

Cardiac Magnetic Resonance Imaging in Pulmonary Arterial Hypertension: Ready for Clinical Practice and Guidelines?

Purpose of Review

Pulmonary arterial hypertension (PAH) is a progressive disease with high mortality. A greater understanding of the physiology and function of the cardiovascular system in PAH will help improve survival. This review covers the latest advances within cardiovascular magnetic resonance imaging (CMR) regarding diagnosis, evaluation of treatment, and prognostication of patients with PAH.

Recent Findings

New CMR measures that have been proven relevant in PAH include measures of ventricular and atrial volumes and function, tissue characterization, pulmonary artery velocities, and arterio-ventricular coupling.

Summary

CMR markers carry prognostic information relevant for clinical care such as treatment response and thereby can affect survival. Future research should investigate if CMR, as a non-invasive method, can improve existing measures or even provide new and better measures in the diagnosis, evaluation of treatment, and determination of prognosis of PAH.

Cardiac Magnetic Resonance in Pulmonary Hypertension-an Update

PURPOSE OF REVIEW

This article reviews advances over the past 3 years in cardiac magnetic resonance (CMR) imaging in pulmonary hypertension (PH). We aim to bring the reader up-to-date with CMR applications in diagnosis, prognosis, 4D flow, strain analysis, T1 mapping, machine learning and ongoing research.

RECENT FINDINGS

CMR volumetric and functional metrics are now established as valuable prognostic markers in PH. This imaging modality is increasingly used to assess treatment response and improves risk stratification when incorporated into PH risk scores. Emerging techniques such as myocardial T1 mapping may play a role in the follow-up of selected patients. Myocardial strain may be used as an early marker for right and left ventricular dysfunction and a predictor for mortality. Machine learning has offered a glimpse into future possibilities. Ongoing research of new PH therapies is increasingly using CMR as a clinical endpoint.

SUMMARY

The last 3 years have seen several large studies establishing CMR as a valuable diagnostic and prognostic tool in patients with PH, with CMR increasingly considered as an endpoint in clinical trials of PH therapies. Machine learning approaches to improve automation and accuracy of CMR metrics and identify imaging features of PH is an area of active research interest with promising clinical utility.

Update on noninvasive imaging of right ventricle dysfunction in pulmonary hypertension

Pulmonary hypertension (PH) is a progressive disease affecting patients across the life span. The pathophysiology primarily involves the pulmonary vasculature and right ventricle (RV), but eventually affects the left ventricular (LV) function as well. Safe, accurate imaging modalities are critical for diagnosis, serial monitoring, and tailored therapy. While cardiac catheterization remains the conventional modality for establishing diagnosis and serial monitoring, noninvasive imaging has gained considerable momentum in providing accurate assessment of the entire RV-pulmonary axis. In this state-of-the-art review, we will discuss the most recent developments in echocardiography, magnetic resonance imaging, and computed tomography in PH evaluation from pediatric to adult population.

Myocardial deformation assessment in patients with precapillary pulmonary hypertension: A cardiac magnetic resonance study

PURPOSE

The purpose of this study was to investigate right atrial and ventricular strain parameters on cardiac magnetic resonance (CMR) in patients with precapillary pulmonary hypertension (PPH) and whether they can aid in the assessment of PPH prognosis.

MATERIALS AND METHODS

Adult patients with groups 1 and 4 PPH were invited to participate in the study. Age- and sex-matched healthy volunteers were also recruited as controls. At baseline, patients underwent clinical examination, N-terminal pro-B-type natriuretic peptide measurement and CMR with feature tracking post-processing (CMR-FT). Healthy controls underwent only CMR-FT. The study's primary endpoint was clinical failure, defined as death, hospitalization or demonstrable clinical deterioration during follow-up. Patients who were unable to perform 6-minute walking test due to musculoskeletal disorders were excluded from the study.

RESULTS

Thirty-six patients (8 men, 28 women; mean age, 50.6±13.8 [SD] years [range: 18.6-78.5years]) and 12 healthy control subjects (5 mean, 7 women; mean age, 40.6±13.5 [SD] years [range: 23.1-64.4years]) were recruited. Right ventricular global longitudinal strain (GLS) was significantly impaired in PPH patients (-20.2±5.3 [SD] % [range: -28.8 to -9.1%] vs. -28.4±3.1% [-33.7 to -22.7%] respectively, P<0.001). The right atrial GLS was significantly impaired in PPH compared to healthy controls (-19.9±4.5% [range: -28.6 to -3.6%] vs. -26.5±4.2% [range: -32.8 to -15.8%] respectively) (P<0.001). Clinical failure occurred in 19 (19/36, 53%) of patients. Right ventricular GLS predicted clinical failure most reliably among CMR parameters (-22.6±3.8 [SD] % [range: -27.6 to -12.7%] for patients without clinical failure vs. -18±5.6 [SD] % [range: -28.8 to -9.1%] for patients with clinical failure; hazard ratio [HR]=1.85; P=0.007; area under the AUC curve=0.75). Lower absolute right atrial GLS was significantly associated with clinical failure (-22.7±3.0 [SD] % [range: -28.6 to -17.7%] for patients without clinical failure vs. -16.9±5.8 [SD] % [range: -24.2 to -3.6%] for patients with clinical failure) (HR=1.53; P=0.035).

CONCLUSION

CMR feature tracking-derived myocardial strain parameters of both the right atrium and ventricle can assist clinicians in the prognosis of PPH.

Identification of Cardiac MRI and Bio-Marker Thresholds for One-Year Survival in Pre-Capillary Pulmonary Hypertension: Prospective Study

Background and objectives: Non-invasive imaging of the heart has an important place in the diagnosis and management of pulmonary arterial hypertension (PAH). The aim of this study was to establish the thresholds of cardiac magnetic resonance imaging (CMRI)-derived biventricular deformation, function parameters, and levels of N-terminal pro brain natriuretic peptide (NT-proBNP) for the prediction of survival of pre-capillary pulmonary hypertension (PHprecap) patients. Materials and Methods: In total, 64 incident PHprecap cases, who underwent CMRI, were consecutively enrolled in a prospective cohort study. Patients underwent a systemic evaluation, including measurement of NT-proBNP, two-dimensional (2D) echocardiography, six-minute walk test (6MWT), CMRI with feature tracking (FT), and right-heart catheterization (RHC). Patients were divided into two groups according to one-year survival (survival and non-survival groups). Survival analysis was performed. Results: One-year survival was 79.6%. The distribution between age, sex, mean pulmonary artery pressure (mPAP), New York Heart Association (NYHA) functional class, and 6MWT did not differ between the groups. Survival was significantly lower in the PAH group associated with connective tissue disease (CTD-PAH), where 44% (n = 4) of patients died during the first year. Univariate analysis revealed that severely reduced right-ventricle (RV) ejection fraction (EF) <25.5%, left-ventricle global longitudinal strain (LV GLS) >−14.18%, and right pulmonary artery (RPA) relative area change (RAC) <19%, and severely increased NT-proBNP level >1738 (ng/L) indicate an increased risk of death in PH_precap patients. Conclusions: Impaired RV systolic function and LV global longitudinal strain, decrease of pulmonary artery distensibility, and CTD-PAH etiology, together with high NT-proBNP level, impair prognosis in pre-capillary PH patients. These findings are important for the risk stratification and management of pre-capillary pulmonary hypertension patients.

Two-dimensional speckle tracking echocardiography detected interventricular dyssynchrony predicts exercise capacity and disease severity in pre-capillary pulmonary hypertension

Background

Right ventricular (RV) intraventricular mechanical dyssynchrony detected by two-dimensional speckle tracking echocardiography (2D-STE) has been reported to be correlated with a decrease in RV contractile efficiency in pulmonary hypertension (PH) patients, while little attention has been paid to biventricular dysfunction. Therefore, we aimed to evaluate the predictive value of 2D-STE detected interventricular dyssynchrony for exercise capacity and disease severity in patients with pre-capillary PH (PcPH).

Methods

Conventional transthoracic echocardiography, 2D-STE and cardiopulmonary exercise tests (CPETs) were performed in all participants. Intra- and interventricular dyssynchrony were calculated as the standard deviation (SD) of the time intervals corrected for heart rate between QRS onset and peak longitudinal strain. Multivariate linear regression analyses were performed to identify independent predictors of peak oxygen consumption (PVO₂) during the CPET. Multivariable logistical regression modeling was used to analyze the associations between interventricular dyssynchrony and risk assessment.

Results

Sixty-six PcPH patients were consecutively recruited (19 male and 47 female, average 35 years old). WHO functional class, N-terminal pro-brain natriuretic peptide (BNP) and body mass index were included as independent predictors in the first multivariate regression analysis of clinical data without echocardiographic parameters (Model-1, r²=0.423, P<0.001). We subsequently added conventional echocardiographic parameters and 2D-STE parameters to the clinical data, RV fractional area change (Model-2, r²=0.417, P<0.001), RV global longitudinal strain (Model-3, r²=0.454, P=0.001), RV intraventricular dyssynchrony (Model-4: r²=0.474, P<0.001) and interventricular dyssynchrony (Model-5, r²=0.483, P<0.001) were identified as independent predictors of PVO₂. Interventricular dyssynchrony, calculated as the SD of the time intervals of nine segments, was independently associated with risk assessment (odd ratio 1.027, 95% CI: 1.003–1.052, P=0.03). The area under the receiver-operating characteristic curve (AUC) was 0.73 (P<0.001).

Conclusions

Interventricular dyssynchrony detected by 2D-STE contributed to a better evaluation of exercise capacity and disease severity in PcPH patients.

Prognostic Value of Left Ventricular Function and Mechanics in Pulmonary Hypertension: A Pilot Cardiovascular Magnetic Resonance Feature Tracking Study

Background and objective: Cardiovascular magnetic resonance (CMR) - based feature tracking (FT) can detect left ventricular (LV) strain abnormalities in pulmonary hypertension (PH) patients, but little is known about the prognostic value of LV function and mechanics in PH patients. The aim of this study was to evaluate LV systolic function by conventional CMR and LV global strains by CMR-based FT analysis in precapillary PH patients, thereby defining the prognostic value of LV function and mechanics. Methods: We prospectively enrolled 43 patients with precapillary PH (mean pulmonary artery pressure (mPAP) 55.91 ± 15.87 mmHg, pulmonary arterial wedge pressure (PAWP) ≤15 mmHg) referred to CMR for PH evaluation. Using FT software, the LV global longitudinal strain (GLS) and global circumferential strain (GCS), also right ventricular (RV) GLS were analyzed. Results: Patients were classified into two groups according to survival (survival/non-survival). LV GLS was significantly reduced in the non-survival group (−12.4% [−19.0–(−7.8)] vs. −18.4% [−22.5–(−15.5)], p = 0.009). By ROC curve analysis, LV GLS > −14.2% (CI: 3.229 to 37.301, p < 0.001) was found to be robust predictor of mortality in PH patients. Univariable analysis using the Cox model showed that severely reduced LV GLS > −14.2%, with good sensitivity (77.8%) and high specificity (93.5%) indicated an increase of the risk of death by 11-fold. LV GLS significantly correlated in PH patients with RV ESVI (r = 0.322, p = 0.035), RV EF (r = 0.444, p < 0.003). Conclusions: LV systolic function and LV global longitudinal strain measurements using CMR-FT correlates with RV dysfunction and is associated with poor clinical outcomes in precapillary PH patients.