Stress cardiac imaging is the current first line investigation for coronary artery disease diagnosis and decision making and an adjunctive tool in a range of non-ischaemic cardiovascular diseases. ...Exercise cardiovascular magnetic resonance (Ex-CMR) has developed over the past 25 years to combine the superior image qualities of CMR with the preferred method of exercise stress. Presently, numerous exercise methods exist, from performing stress on an adjacent CMR compatible treadmill to in-scanner exercise, most commonly on a supine cycle ergometer. Cardiac conditions studied by Ex-CMR are broad, commonly investigating ischaemic heart disease and congenital heart disease but extending to pulmonary hypertension and diabetic heart disease. This review presents an in-depth assessment of the various Ex-CMR stress methods and the varied pulse sequence approaches, including those specially designed for Ex-CMR. Current and future developments in image acquisition are highlighted, and will likely lead to a much greater clinical use of Ex-CMR across a range of cardiovascular conditions.
Aims
Left ventricular (LV) thrombus is increasingly detected in patients with and without ischaemic heart disease due to the increased availability of cardiac magnetic resonance imaging. Risk factors ...include anterior ST elevation myocardial infarction, delayed reperfusion therapy, and non‐ischaemic cardiomyopathy with severe LV systolic dysfunction. We aimed to report the characteristics and outcomes of patients with LV thrombus treated with either vitamin K antagonist (VKA) or direct oral anticoagulants (DOAC) with a view to describing differences in efficacy, specifically, subsequent thromboembolic events, thrombus resolution, and also side effects of therapy including clinically significant bleeding.
Methods and results
We conducted a retrospective, observational cohort study of patients diagnosed with LV thrombus between 1 December 2012 and 30 June 2018 and treated with either DOAC or VKA. We recorded patient demographics, past medical history, prescribed medications, and baseline investigations. The primary outcomes were rates of thromboembolism and clinically significant bleeding, with secondary outcomes of thrombus resolution on repeat cardiac imaging, repeat hospitalization, and all‐cause mortality. During the study period, 84 patients were diagnosed with and managed for LV thrombus. Of these, 62 received VKA and 22 DOAC including 13 prescribed rivaroxaban, eight apixaban, and one dabigatran. Most patients 75 (89%) were male with an average age of 62 ± 14 years. Ischaemic heart disease was the cause of LV impairment in 73 (87%) patients. Baseline characteristics were similar between groups at baseline. Most n = 55 (65%) were co‐prescribed a single antiplatelet agent and 32 (38%) received dual‐antiplatelet therapy. During an average follow‐up of 3.0 ± 1.4 years, there were no statistically significant differences between VKA and DOAC in rates of stroke (2% vs. 0%, P = 0.55), other thromboemboli (2% vs. 0%, P = 0.55), or clinically significant bleeding (10% vs. 0%, P = 0.13). The average interval to cardiac imaging follow‐up was 233 ± 251 days and was not different between groups (P = 0.83), and there was no difference in the rate of resolution of thrombus (76% vs. 65% P = 0.33). Rehospitalization (50% vs. 45%: P = 0.53) and all‐cause mortality (10% vs. 14%; P = 0.61) were also similar.
Conclusions
Our data suggest that DOACs are likely to be at least as effective and safe as VKA for stroke prevention in patients with LV thrombus and, despite their lack of a licence for this indication, are therefore likely to represent a reasonable and more convenient option for this setting. The optimal timing and type of anticoagulation for LV thrombus, as well as the role of screening for high‐risk patients, should be tested in prospective, randomized trials.
When feasible, guidelines recommend mitral valve repair (MVr) over mitral valve replacement (MVR) to treat primary mitral regurgitation (MR), based upon historic outcome studies and transthoracic ...echocardiography (TTE) reverse remodeling studies. Cardiovascular magnetic resonance (CMR) offers reference standard biventricular assessment with superior MR quantification compared to TTE. Using serial CMR in primary MR patients, we aimed to investigate cardiac reverse remodeling and residual MR post-MVr vs MVR with chordal preservation.
83 patients with ≥ moderate-severe MR on TTE were prospectively recruited. 6-min walk tests (6MWT) and CMR imaging including cine imaging, aortic/pulmonary through-plane phase contrast imaging, T1 maps and late-gadolinium-enhanced (LGE) imaging were performed at baseline and 6 months after mitral surgery or watchful waiting (control group).
72 patients completed follow-up (Controls = 20, MVr = 30 and MVR = 22). Surgical groups demonstrated comparable baseline cardiac indices and co-morbidities. At 6-months, MVr and MVR groups demonstrated comparable improvements in 6MWT distances (+ 57 ± 54 m vs + 64 ± 76 m respectively, p = 1), reduced indexed left ventricular end-diastolic volumes (LVEDVi; − 29 ± 21 ml/m2 vs − 37 ± 22 ml/m2 respectively, p = 0.584) and left atrial volumes (− 23 ± 30 ml/m2 and − 39 ± 26 ml/m2 respectively, p = 0.545). At 6-months, compared with controls, right ventricular ejection fraction was poorer post-MVr (47 ± 6.1% vs 53 ± 8.0% respectively, p = 0.01) compared to post-MVR (50 ± 5.7% vs 53 ± 8.0% respectively, p = 0.698). MVR resulted in lower residual MR-regurgitant fraction (RF) than MVr (12 ± 8.0% vs 21 ± 11% respectively, p = 0.022). Baseline and follow-up indices of diffuse and focal myocardial fibrosis (Native T1 relaxation times, extra-cellular volume and quantified LGE respectively) were comparable between groups. Stepwise multiple linear regression of indexed variables in the surgical groups demonstrated baseline indexed mitral regurgitant volume as the sole multivariate predictor of left ventricular (LV) end-diastolic reverse remodelling, baseline LVEDVi as the most significant independent multivariate predictor of follow-up LVEDVi, baseline indexed LV end-systolic volume as the sole multivariate predictor of follow-up LV ejection fraction and undergoing MVR (vs MVr) as the most significant (p < 0.001) baseline multivariate predictor of lower residual MR.
In primary MR, MVR with chordal preservation may offer comparable cardiac reverse remodeling and functional benefits at 6-months when compared to MVr. Larger, multicenter CMR studies are required, which if the findings are confirmed could impact future surgical practice.
Sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce the risk of major adverse cardiovascular (CV) events and hospitalization for heart failure (HF) in patients with type 2 diabetes (T2D). Using ...CV MRI (CMR) and
P-MRS in a longitudinal cohort study, we aimed to investigate the effects of the selective SGLT2 inhibitor empagliflozin on myocardial energetics and cellular volume, function, and perfusion. Eighteen patients with T2D underwent CMR and
P-MRS scans before and after 12 weeks' empagliflozin treatment. Plasma N-terminal prohormone B-type natriuretic peptide (NT-proBNP) levels were measured. Ten volunteers with normal glycemic control underwent an identical scan protocol at a single visit. Empagliflozin treatment was associated with significant improvements in phosphocreatine-to-ATP ratio (1.52 to 1.76,
= 0.009). This was accompanied by a 7% absolute increase in the mean left ventricular ejection fraction (
= 0.001), 3% absolute increase in the mean global longitudinal strain (
= 0.01), 8 mL/m
absolute reduction in the mean myocardial cell volume (
= 0.04), and 61% relative reduction in the mean NT-proBNP (
= 0.05) from baseline measurements. No significant change in myocardial blood flow or diastolic strain was detected. Empagliflozin thus ameliorates the "cardiac energy-deficient" state, regresses adverse myocardial cellular remodeling, and improves cardiac function, offering therapeutic opportunities to prevent or modulate HF in T2D.
Four-dimensional-flow cardiac MR (4DF-MR) offers advantages in primary mitral regurgitation. The relationship between 4DF-MR-derived mitral regurgitant volume (MR-Rvol) and the post-operative left ...ventricular (LV) reverse remodeling has not yet been established.
To ascertain if the 4DF-MR-derived MR-Rvol correlates with the LV reverse remodeling in primary mitral regurgitation.
Prospective, single-center, two arm, interventional vs. nonintervention observational study.
Forty-four patients (male N = 30; median age 68 59-75) with at least moderate primary mitral regurgitation; either awaiting mitral valve surgery (repair MVr, replacement MVR) or undergoing "watchful waiting" (WW).
5 T/Balanced steady-state free precession (bSSFP) sequence/Phase contrast imaging/Multishot echo-planar imaging pulse sequence (five shots).
Patients underwent transthoracic echocardiography (TTE), phase-contrast MR (PMRI), 4DF-MR and 6-minute walk test (6MWT) at baseline, and a follow-up PMRI and 6MWT at 6 months. MR-Rvol was quantified by PMRI, 4DF-MR, and TTE by one observer. The pre-operative MR-Rvol was correlated with the post-operative decrease in the LV end-diastolic volume index (LVEDVi).
Included Student t-test/Mann-Whitney test/Fisher's exact test, Bland-Altman plots, linear regression analysis and receiver operating characteristic curves. Statistical significance was defined as P < 0.05.
While Bland-Altman plots demonstrated similar bias between all the modalities, the limits of agreement were narrower between 4DF-MR and PMRI (bias 15; limits of agreement -36 mL to 65 mL), than between 4DF-MR and TTE (bias -8; limits of agreement -106 mL to 90 mL) and PMRI and TTE (bias -23; limits of agreement -105 mL to 59 mL). Linear regression analysis demonstrated a significant association between the MR-Rvol and the post-operative decrease in the LVEDVi, when the MR-Rvol was quantified by PMRI and 4DF-MR, but not by TTE (P = 0.73). 4DF-MR demonstrated the best diagnostic performance for reduction in the post-operative LVEDVi with the largest area under the curve (4DF-MR 0.83; vs. PMRI 0.78; and TTE 0.51; P = 0.89).
This study demonstrates the potential clinical utility of 4DF-MR in the assessment of primary mitral regurgitation.
2 TECHNICAL EFFICACY: Stage 5.
Background
Hypertrophic cardiomyopathy (HCM) remains the commonest cause of sudden cardiac death among young athletes. Differentiating between physiologically adaptive left ventricular (LV) ...hypertrophy observed in athletes' hearts and pathological HCM remains challenging. By quantifying the diffusion of water molecules, diffusion tensor imaging (DTI) MRI allows voxelwise characterization of myocardial microstructure.
Purpose
To explore microstructural differences between healthy volunteers, athletes, and HCM patients using DTI.
Study Type
Prospective cohort.
Population
Twenty healthy volunteers, 20 athletes, and 20 HCM patients.
Field Strength/Sequence
3T/DTI spin echo.
Assessment
In‐house MatLab software was used to derive mean diffusivity (MD) and fractional anisotropy (FA) as markers of amplitude and anisotropy of the diffusion of water molecules, and secondary eigenvector angles (E2A)—reflecting the orientations of laminar sheetlets.
Statistical Tests
Independent samples t‐tests were used to detect statistical significance between any two cohorts. Analysis of variance was utilized for detecting the statistical difference between the three cohorts. Statistical tests were two‐tailed. A result was considered statistically significant at P ≤ 0.05.
Results
DTI markers were significantly different between HCM, athletes, and volunteers. HCM patients had significantly higher global MD and E2A, and significantly lower FA than athletes and volunteers. (MDHCM = 1.52 ± 0.06 × 10−3 mm2/s, MDAthletes = 1.49 ± 0.03 × 10−3 mm2/s, MDvolunteers = 1.47 ± 0.02 × 10−3 mm2/s, P < 0.05; E2AHCM = 58.8 ± 4°, E2Aathletes = 47 ± 5°, E2Avolunteers = 38.5 ± 7°, P < 0.05; FAHCM = 0.30 ± 0.02, FAAthletes = 0.35 ± 0.02, FAvolunteers = 0.36 ± 0.03, P < 0.05). HCM patients had significantly higher E2A in their thickest segments compared to the remote (E2Athickest = 66.8 ± 7, E2Aremote = 51.2 ± 9, P < 0.05).
Data Conclusion
DTI depicts an increase in amplitude and isotropy of diffusion in the myocardium of HCM compared to athletes and volunteers as reflected by increased MD and decreased FA values. While significantly higher E2A values in HCM and athletes reflect steeper configurations of the myocardial sheetlets than in volunteers, HCM patients demonstrated an eccentric rise in E2A in their thickest segments, while athletes demonstrated a concentric rise. Further studies are required to determine the diagnostic capabilities of DTI.
Evidence Level
1
Technical Efficacy Stage
2
Abstract
Aims
The 2016 European Society of Cardiology Heart Failure Guidelines defined a new category: heart failure with mid-range ejection fraction (HFmrEF) of 40–49%. This new category was ...highlighted as having limited evidence and research was advocated into underlying characteristics, pathophysiology, and diagnosis. We used multi-parametric cardiovascular magnetic resonance (CMR) to define the cardiac phenotype of presumed non-ischaemic HFmrEF.
Methods and results
Patients (N = 300, 62.7 ± 13 years, 63% males) with a clinical diagnosis of heart failure with no angina symptoms, history of myocardial infarction, or coronary intervention were prospectively recruited. Patients underwent clinical assessment and CMR including T1 mapping, extracellular volume (ECV) mapping, late gadolinium enhancement, and measurement of myocardial blood flow at rest and maximal hyperaemia. Of 273 patients in the final analysis, 93 (34%) patients were categorized as HFmrEF, 46 (17%) as heart failure with preserved ejection fraction (HFpEF), and 134 (49%) as heart failure with reduced ejection fraction (HFrEF). Nineteen (20%) patients with HFmrEF had evidence of occult ischaemic heart disease. Diffuse fibrosis and hyperaemic myocardial blood flow were similar in HFmrEF and HFpEF, but HFmrEF showed significantly lower native T1 (1311 ± 32 vs. 1340 ± 45 ms, P < 0.001), ECV (24.6 ± 3.2 vs. 26.3 ± 3.1%, P < 0.001), and higher myocardial perfusion reserve (2.75 ± 0.84 vs. 2.28 ± 0.84, P < 0.001) compared with HFrEF.
Conclusion
Patients with HFmrEF share most phenotypic characteristics with HFpEF, including the degree of microvascular impairment and fibrosis, but have a high prevalence of occult ischaemic heart disease similar to HFrEF. Further work is needed to confirm how the phenotype of HFmrEF responds to medical therapy.
Graphical Abstract
Graphical Abstract
There is limited research into the mechanisms of heart failure with mildly reduced ejection fraction (HFmrEF, 40–49%). Using cardiovascular magnetic resonance, we have shown that patients with HFmrEF share most phenotypic characteristics with heart failure with preserved ejection fraction (HFpEF, ≥50%), including the degree of microvascular impairment and fibrosis. However, they also have a high prevalence of occult ischaemic heart disease similar to heart failure with reduced ejection fraction (HFrEF, <40%).
Purpose
Exercise imaging using current modalities can be challenging. This was patient focused study to establish the feasibility and reproducibility of exercise-cardiovascular magnetic resonance ...imaging (EX-CMR) acquired during continuous in-scanner exercise in asymptomatic patients with primary mitral regurgitation (MR).
Methods
This was a prospective, feasibility study. Biventricular volumes/function, aortic flow volume, MR volume (MR-Rvol) and regurgitant fraction (MR-RF) were assessed at rest and during low- (Low-EX) and moderate-intensity exercise (Mod-EX) in asymptomatic patients with primary MR.
Results
Twenty-five patients completed EX-CMR without complications. Whilst there were no significant changes in the left ventricular (LV) volumes, there was a significant increase in the LVEF (rest 63 ± 5% vs. Mod-EX 68 ± 6%;
p
= 0.01). There was a significant reduction in the right ventricular (RV) end-systolic volume (rest 68 ml(60–75) vs. Mod-EX 46 ml(39–59);
p
< 0.001) and a significant increase in the RV ejection fraction (rest 55 ± 5% vs. Mod-EX 65 ± 8%;
p
< 0.001). Whilst overall, there were no significant group changes in the MR-Rvol and MR-RF, individual responses were variable, with MR-Rvol increasing by ≥ 15 ml in 4(16%) patients and decreasing by ≥ 15 ml in 9(36%) of patients. The intra- and inter-observer reproducibility of LV volumes and aortic flow measurements were excellent, including at Mod-EX.
Conclusion
EX-CMR is feasible and reproducible in patients with primary MR. During exercise, there is an increase in the LV and RV ejection fraction, reduction in the RV end-systolic volume and a variable response of MR-Rvol and MR-RF. Understanding the individual variability in MR-Rvol and MR-RF during physiological exercise may be clinically important.
PDF
