Cardiac reverse remodeling in primary mitral regurgitation: mitral valve replacement vs. mitral valve repair

BACKGROUND

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.

METHODS

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).

RESULTS

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.

CONCLUSION

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.

Perioperative cerebral microinfarction and quality of life following mitral valve surgery

Introduction

Mitral regurgitation (MR) is the second most common valvular pathology worldwide. When untreated, severe MR is associated with significant morbidity and mortality. Mitral valve surgery is recommended in symptomatic patients and those with evidence of adverse left atrial or left ventricular remodelling. Although uncommon, stroke is a recognised complication of mitral valve surgery and is associated with unfavourable outcomes. While silent cerebral microinfarction has been described following cardiac surgery, its incidence in mitral valve surgery and its impact on quality of life is presently unknown. The main aim of this study was to assess the incidence of perioperative cerebral microinfarction following mitral valve surgery and its impact on medium-term health-related quality of life (HRQoL).

Methods

Cerebral diffusion-weighted magnetic resonance imaging (DWI-MRI) was conducted pre-operatively and prior to discharge in 31 patients undergoing mitral valve surgery for mitral regurgitation. Blinded analysis was conducted by a neuro-radiologist. HRQoL assessment was undertaken at baseline and at a 6-month follow up with EuroQoL-5 dimensions (EQ-5D-5L) and Hospital Anxiety and Depression Scale (HADS) questionnaires.

Results

Thirty-one patients underwent paired cerebral DWI-MRI (mitral valve replacement (MVR) n=16 [52%] and mitral valve repair (MVr) n=15 [48%]). Prevalence of atrial fibrillation was similar in both groups (MVR n=9 [56%] vs. MVr n=7 [47%], p=0.59). Peri-operative cerebral microinfarction occurred in 9 patients (29%). Embolic events were numerically higher in the MVR group versus MVr group, but not statistically significant (n=7 [44%] vs. n=2 [13%], p=0.06). Presence of multiple lesions, large lesions &gt;5mm, small lesions &lt;5mm and the total number of lesions did not differ significantly between the two groups. Median volume of lesions was higher in the MVR group versus MVr (0 [0–0.4] vs 0 [0–0], p=0.04) (Table 1).

There was no difference in the mean change in HRQoL during 6m follow up between patients with peri-operative cerebral microinfarction and those with no detectable embolic events (Table 2). Within group comparison (MVR group and MVr group) also did not demonstrate any significant difference.

Conclusions

Peri-operative cerebral microinfarction occurred in almost a third of patients undergoing mitral valve surgery, with higher volume of lesions following MVR. These lesions however, did not exhibit significant impact on medium term health-related quality of life.

Funding Acknowledgement

Type of funding sources: None.

Successful percutaneous mitral valve leaflet repair for primary mitral regurgitation results in functional improvement and positive cardiac reverse remodelling

Funding Acknowledgements

Type of funding sources: None.

Background

Percutaneous mitral valve leaflet repair can be an effective treatment for primary mitral regurgitation (MR) patients deemed high-risk for surgery. Accurate assessment of cardiac reverse remodelling is essential to optimise future patient selection. Cardiovascular magnetic resonance (CMR) is the reference standard for cardiac volumetric assessment and compared to transthoracic echocardiography (TTE) provides superior reproducibility in MR quantification. Prior CMR studies have analysed cardiac reverse remodelling following percutaneous intervention in combined cohorts of primary and secondary MR patients. However, as aetiology of MR can significantly impact outcomes, focused studies are warranted.

Purpose

Assess cardiac reverse remodelling and quantify changes in MR following percutaneous mitral valve leaflet repair for primary MR using the reference standard (CMR).

Methods

12 patients with at least moderate-severe MR on TTE were prospectively recruited to undergo CMR imaging and 6-minute walk tests (6MWT) at baseline and 6 months following percutaneous mitral valve leaflet repair (MitraClip). CMR protocol involved: left-ventricular (LV) short axis cines (bSSFP, SENSE-2, 10mm, no gap), transaxial right-ventricular (RV) cines (bSSFP, SENSE-2, 8mm, no gap), two and four chamber cines and aortic through-plane phase contrast imaging, planned at the sino-tubular junction. MR was quantified indirectly using LV and aortic stroke volumes.

Results

12 patients underwent percutaneous mitral valve leaflet repair (MitraClip) for posterior mitral valve leaflet prolapse, however 1 patient declined follow up after single-leaflet clip detachment resulting in 11 patients (age 83 ± 5years, 9 male) completing follow up imaging. At 6-months: significant improvements occurred in New York Heart Association functional class (Table 1) and 6MWT distances (223 ± 71m to 281 ± 65m, p = 0.005) and significant reductions occurred in indexed left ventricular end-diastolic volumes (LVEDVi) (118 ± 21ml/m2 to 94 ± 27ml/m2, p = 0.001), indexed left ventricular end-systolic volumes (58 ± 19ml/m2 to 48 ± 21ml/m2, p = 0.007) and quantitated MR volume (55 ± 22ml to 24 ± 12ml, p = 0.003) and MR fraction (49 ± 9.4% to 29 ± 14%, p= &lt;0.001). There were no statistically significant changes in left ventricular ejection fraction (LVEF), right ventricular dimensions/ejection fraction or bi-atrial dimensions (Table 1). All patients demonstrated decreased LVEDVi and quantified MR (Figure 1).

Conclusion

Successful percutaneous mitral valve leaflet repair for primary MR results in reduction in MR, positive LV reverse remodelling, preservation of LVEF, and functional improvements. Larger CMR studies are now required to further guide optimal patient selection.

Detrimental Immediate- and Medium-Term Clinical Effects of Right Ventricular Pacing in Patients With Myocardial Fibrosis

BACKGROUND

Long-term right ventricular (RV) pacing leads to heart failure or a decline in left ventricular (LV) function in up to a fifth of patients. We aimed to establish whether patients with focal fibrosis detected on late gadolinium enhancement cardiovascular magnetic resonance (CMR) have deterioration in LV function after RV pacing.

METHODS

We recruited 84 patients with LV ejection fraction ≥40% into 2 observational CMR studies. Patients (n=34) with a dual-chamber device and preserved atrioventricular conduction underwent CMR in 2 asynchronous pacing modes (atrial asynchronous and dual-chamber asynchronous) to compare intrinsic atrioventricular conduction with forced RV pacing. Patients (n=50) with high-grade atrioventricular block underwent CMR before and 6 months after pacemaker implantation to investigate the medium-term effects of RV pacing.

RESULTS

The key findings were (1) initiation of RV pacing in patients with fibrosis, compared with those without, was associated with greater immediate changes in both LV end-systolic volume index (5.3±3.5 versus 2.1±2.4 mL/m2; P<0.01) and LV ejection fraction (-5.7±3.4% versus -3.2±2.6%; P=0.02); (2) medium-term RV pacing in patients with fibrosis, compared with those without, was associated with greater changes in LV end-systolic volume index (8.0±10.4 versus -0.6±7.3 mL/m2; P=0.008) and LV ejection fraction (-12.3±7.9% versus -6.7±6.2%; P=0.012); (3) patients with fibrosis did not experience an improvement in quality of life, biomarkers, or functional class after pacemaker implantation; (4) after 6 months of RV pacing, 10 of 50 (20%) patients developed LV ejection fraction <35% and were eligible for upgrade to cardiac resynchronization according to current guidelines. All 10 patients had fibrosis on their preimplant baseline scan and were identified by >1.1 g of fibrosis with 90% sensitivity and 70% specificity.

CONCLUSIONS

Fibrosis detected on CMR is associated with immediate- and medium-term deterioration in LV function following RV pacing and could be used to identify those at risk of heart failure before pacemaker implantation.

Acute Microstructural Changes after ST-Segment Elevation Myocardial Infarction Assessed with Diffusion Tensor Imaging

Background Cardiac diffusion tensor imaging (cDTI) allows for in vivo characterization of myocardial microstructure. In cDTI, mean diffusivity and fractional anisotropy (FA)-markers of magnitude and anisotropy of diffusion of water molecules-are known to change after myocardial infarction. However, little is known about regional changes in helix angle (HA) and secondary eigenvector angle (E2A), which reflects orientations of laminar sheetlets, and their association with long-term recovery of left ventricular ejection fraction (LVEF). Purpose To assess serial changes in cDTI biomarkers in participants following ST-segment elevation myocardial infarction (STEMI) and to determine their associations with long-term left ventricular remodeling. Materials and Methods In this prospective study, 30 participants underwent cardiac MRI (3 T) after STEMI at 5 days and 3 months after reperfusion (National Institute of Health Research study no. 33963 and Research Ethics no. REC17/YH/0062). Spin-echo cDTI with second-order motion-compensation (approximate duration, 13 minutes; three sections; 18 noncollinear diffusion-weighted scans with b values of 100 sec/mm² [three acquisitions], 200 sec/mm² [three acquisitions], and 500 sec/mm² [12 acquisitions]), functional images, and late gadolinium enhancement images were obtained. Multiple regression analysis was used to assess associations between acute cDTI parameters and 3-month LVEF. Results Acutely infarcted myocardium had reduced FA, E2A, and myocytes with right-handed orientation (RHM) on HA maps compared with remote myocardium (mean remote FA = 0.36 ± 0.02 [standard deviation], mean infarcted FA = 0.25 ± 0.03, P < .001; mean remote E2A = 55° ± 9, mean infarcted E2A = 49° ± 10, P < .001; mean remote RHM = 16% ± 6, mean infarcted RHM = 9% ± 5, P < .001). All three parameters (FA, E2A, and RHM) correlated with 3-month LVEF (r = 0.68, r = 0.59, and r = 0.53, respectively), with acute FA being independently predictive of 3-month LVEF (standardized β = 0.56, P = .008) after multivariable analysis adjusting for factors, including acute LVEF and infarct size. Conclusion After ST-segment elevation myocardial infarction, diffusion becomes more isotropic in acutely infarcted myocardium as reflected by decreased fractional anisotropy. Reductions in secondary eigenvector angle suggest that the myocardial sheetlets are unable to adopt their usual steep orientations in systole, whereas reductions in myocytes with right-handed orientation on helix angle maps are likely reflective of a loss of organization among subendocardial myocytes. Correlations between these parameters and 3-month left ventricular ejection fraction highlight the potential clinical use of cardiac diffusion tensor imaging after myocardial infarction in predicting long-term remodeling. © RSNA, 2021 Online supplemental material is available for this article.

Detrimental immediate and long-term clinical effects of right ventricular pacing in patients with myocardial fibrosis

Funding Acknowledgements

Type of funding sources: None.

Background

Long-term right ventricular (RV) pacing leads to heart failure or a decline in left ventricular (LV) function in up to a fifth of patients.

Objectives

We aimed to establish whether patients with focal fibrosis detected on late gadolinium enhancement cardiovascular magnetic resonance (CMR) have deterioration in LV function after RV pacing.

Methods

We recruited 110 patients (84 in final analysis) into two observational CMR studies. Patients (n = 34) with a dual chamber device and preserved atrioventricular (AV) conduction underwent CMR in two asynchronous pacing modes (AOO & DOO) to compare intrinsic conduction with RV pacing. Patients (n = 50) with high-grade AV block underwent CMR before and 6 months after pacemaker implantation to investigate the long-term effects of RV pacing.

Results: The three key findings were

1) Initiation of RV pacing in patients with fibrosis, compared to those without, was associated with greater immediate changes in both LV end-systolic volume index (LVESVi) (5.3 ± 3.5 vs 2.1 ± 2.4 mL/m2; p &lt; 0.01) and LV ejection fraction (LVEF) (-5.7 ± 3.4% vs -3.2 ± 2.6%; p = 0.02); 2) Long-term RV pacing in patients with fibrosis, compared to those without, was associated with greater changes in LVESVi (8.0 ± 10.4 vs -0.6 ± 7.3 mL/m2; p = 0.008) and LVEF (-12.3 ± 7.9 vs -6.7 ± 6.2%; p = 0.012); 3) Patients with fibrosis did not experience an improvement in quality of life, biomarkers or functional class after pacemaker implantation.

Conclusions

Fibrosis detected on CMR is associated with immediate and long-term deterioration in LV function following RV pacing and could be used to identify those at risk of heart failure prior to pacemaker implantation.

Characteristics before and after pacing Study 1 No fibrosis (n = 16) Fibrosis (n = 18) AOO DOO p-value AOO DOO p-value LVEDVi - mL/m&sup2; 66 ± 13 66 ± 12 0.67 78 ± 14 79 ± 13 0.34 LVESVi - mL/m&sup2; 30 ± 10 32 ± 9 0.003 38 ± 11 43 ± 12 &lt;0.001 LVEF - % 56 ± 6 53 ± 5 &lt;0.001 52 ± 8 47 ± 9 &lt;0.001 Mechanical Dyssynchrony index - ms 61 ± 17 71 ± 25 0.07 81 ± 18 89 ± 21 0.04 Study 2 No fibrosis (n = 19) Fibrosis (n = 31) Pre-PPM Post-PPM p-value Pre-PPM Post-PPM p-value LVEDVi -mL/m&sup2; 88 ± 21 73 ± 14 &lt;0.001 90 ± 18 83 ± 21 0.007 LVESVi -mL/m&sup2; 35 ± 9 34 ± 9 0.71 41 ± 14 49 ± 21 0.001 LVEF - % 60 ± 5 54 ± 7 &lt;0.001 56 ± 8 43 ± 12 &lt;0.001 Mechanical Dyssynchrony index - ms 70 ± 29 81 ± 22 0.15 84 ± 30 98 ± 31 0.03 Abstract Figure. Mechanism for heart failure after pacing

Feasibility and reproducibility of a cardiovascular magnetic resonance free-breathing, multi-shot, navigated image acquisition technique for ventricular volume quantification during continuous exercise

Background

Cardiovascular magnetic resonance (CMR) image acquisition techniques during exercise typically requires either transient cessation of exercise or complex post-processing, potentially compromising clinical utility. We evaluated the feasibility and reproducibility of a navigated image acquisition method for ventricular volumes assessment during continuous physical exercise.

Methods

Ten healthy volunteers underwent supine cycle ergometer (Lode) exercise CMR on two separate occasions using a free-breathing, multi-shot, navigated, balanced steady-state free precession cine pulse sequence. Images were acquired at 3-stages, baseline and during steady-state exercise at 55% and 75% maximal heart rate (HR_max), based on a prior supine cardiopulmonary exercise test. Intra-and inter-observer variability and inter-scan reproducibility were derived. Clinical feasibility was tested in a separate cohort of patients with severe mitral regurgitation (n=6).

Results

End-diastolic volume (EDV) of both LV and RV decreased during exercise at 55% and 75% HR_max, although a reduction in RVEDV index was only observed at 75% HR_max. Ejection fractions (EF) for both ventricles were significantly higher at 75% HR_max compared to their respective baselines (LVEF 68%±3% vs. 58%±5%, P=0.001; RVEF 66%±4% vs. 58%±7%, P=0.02). Intra-observer and inter-observer reproducibility of LV parameters was excellent at all 3-stages. Although measurements of RVESV were more variable during exercise, the reproducibility of both RVEF and RV cardiac index was excellent (CV <10%). Inter-scan LV and RV ejection fraction were highly reproducible at all 3 stages, although inter-scan reproducibility of indexed RVESV was only moderate. The protocol was well tolerated by all patients.

Conclusions

Exercise CMR using a free-breathing, multi-shot, navigated cine imaging method allows simultaneous assessment of left and right ventricular volumes during continuous exercise. Intra- and inter-observer reproducibility were excellent. Inter-scan LV and RV ejection fraction were also highly reproducible.

P589Assessment of cardiac reverse remodelling following mitral valve repair and mitral valve replacement in degenerative mitral regurgitation: a cardiovascular magnetic resonance study

Background

Mitral valve (MV) repair is currently recommended over replacement (1). The guidelines suggesting this are however based on historic evidence which compared outdated techniques of MV replacement. Recent data cast doubts on its validity in the current era of chordal-preservation techniques in MV replacement.

Purpose

Using cardiovascular magnetic resonance (CMR) imaging, this study aimed to assess the impact of MV repair and MV replacement on cardiac left ventricular (LV) reverse remodelling.

Methods

65 patients with moderate-severe and severe mitral regurgitation (MR) were prospectively recruited. Of these, 37 patients (59% men, 65±15 years) to date with paired CMR scans at baseline and at 6 months were evaluated. Patients either underwent MV repair (n=9), MV replacement (n=10) or watchful waiting (n=18). The CMR protocol included cines for left ventricle (LV), left atria (LA), and aortic flow assessment. The LA and LV parameters, and MR fraction were analysed.

Results

At 6 months, both the MV repair and replacement groups exhibited a reduction in LV end-diastolic volume (LVEDV) and LA volumes when compared to the control group. The indexed LVEDV decreased significantly from 129±33ml/m2 to 99±37ml/m2, p<0.001 in the repair group, from 118±24ml/m2 to 90±26ml/m2, p<0.001 in the replacement group and remained unchanged in the control group 115±25ml/m2 to 113±25ml/m2, p=0.53. The absolute reduction in indexed LVEDV was not significantly different between the repair and replacement groups (−30±15ml/m2 vs −29±19ml/m2, repair vs replacement, p=1.00). Similarly, both surgical groups also sustained an equal degree of LA size reduction (−42±26ml/m2 vs −36±23ml/m2, repair vs replacement; p=1.00). There was a decline in the global postoperative LV ejection fraction (Table 1). The degree of reduction in LV ejection fraction however did not differ between the repair and replacement group (−9±6% vs −6±8%, repair vs replacement; p=1.00). Those undergoing surgery experienced a significant reduction in their MR severity, although those with replacement had a more effective reduction in MR severity (MR fraction for repair: 47±9% to 15±10%, p<0.001 vs replacement: 41±13% to 5±4%, p<0.001).

Conclusion

MV surgery leads to atrial and left ventricular reverse remodelling, and a decline in global LV ejection fraction. In this small series, MV replacement with chordal preservation showed similar cardiac reverse remodelling benefits to MV repair. Although residual MR is often seen following repair, this did not lead to less favourable cardiac reverse remodelling.

Acknowledgement/Funding

Leeds NIHR infrastructure

Regression of Left Ventricular Mass in Athletes Undergoing Complete Detraining Is Mediated by Decrease in Intracellular but Not Extracellular Compartments

BACKGROUND

Athletic cardiac remodeling can occasionally be difficult to differentiate from pathological hypertrophy. Detraining is a commonly used diagnostic test to identify physiological hypertrophy, which can be diagnosed if hypertrophy regresses. We aimed to establish whether athletic cardiac remodeling assessed by cardiovascular magnetic resonance is mediated by changes in intracellular or extracellular compartments and whether this occurs by 1 or 3 months of detraining.

METHODS

Twenty-eight athletes about to embark on a period of forced detraining due to incidental limb bone fracture underwent clinical assessment, ECG, and contrast-enhanced cardiovascular magnetic resonance within a week of their injury and then 1 month and 3 months later.

RESULTS

After 1 month of detraining, there was reduction in left ventricular (LV) mass (130±28 to 121±25 g; P<0.0001), increase in native T1 (1225±30 to 1239±30 ms; P=0.02), and extracellular volume fraction (24.5±2.3% to 26.0±2.6%; P=0.0007) with no further changes by 3 months. The decrease in LV mass was mediated by a decrease in intracellular compartment volume (94±22 to 85±19 mL; P<0.0001) with no significant change in the extracellular compartment volume. High LV mass index, low native T1, and low extracellular volume fraction at baseline were all predictive of regression in LV mass in the first month.

CONCLUSIONS

Regression of athletic LV hypertrophy can be detected after just 1 month of complete detraining and is mediated by a decrease in the intracellular myocardial compartment with no change in the extracellular compartment. Further studies are needed in athletes with overt and pathological hypertrophy to establish whether native T1 and extracellular volume fraction may complement electrocardiography, echocardiography, cardiopulmonary exercise testing, and genetic testing in predicting the outcome of detraining.

Clinical evaluation of two dark blood methods of late gadolinium quantification of ischemic scar

BACKGROUND

Late gadolinium enhancement (LGE) imaging was validated for diagnosis and quantification of myocardial infarction (MI). Despite good contrast between scar and normal myocardium, contrast between blood pool and myocardial scar can be limited. Dark blood LGE sequences attempt to overcome this issue.

PURPOSE

To evaluate T₁ rho (T₁ ρ)-prepared dark blood sequence and compare to blood nulled (BN) phase sensitive inversion recovery (PSIR) and standard myocardium nulled (MN) PSIR for detection and quantification of scar.

STUDY TYPE

Prospective.

POPULATION

Thirty patients with prior MI.

FIELD STRENGTH/SEQUENCE

Patients underwent identical 1.5 T MRI protocols. Following routine LGE imaging, a slice with scar, remote myocardium, and blood pool was selected. PSIR LGE was repeated with inversion time set to MN, to BN, and T₁ ρ FIDDLE (flow-independent dark-blood delayed enhancement) in random order.

ASSESSMENT

Three observers. Qualitative assessment of confidence scores in scar detection and degree of transmurality. Quantitative assessment of myocardial scar mass (grams), and contrast-to-noise ratio (CNR) measurements between scar, blood pool, and myocardium.

STATISTICAL TESTS

Repeated-measures analysis of variance (ANOVA) with Bonferroni correction, coefficient of variation, and the Cohen κ statistic.

RESULTS

CNR_scar-blood was significantly increased for both BN (27.1 ± 10.4) and T₁ ρ (30.2 ± 15.1) compared with MN (15.3 ± 8.4 P < 0.001 for both sequences). There was no significant difference in CNR_scar-myo between BN (55.9 ± 17.3) and MN (51.1 ± 17.8 P = 0.512); both had significantly higher CNR_scar-myo compared with the T₁ ρ (42.6 ± 16.9 P = 0.007 and P = 0.014, respectively). No significant difference in scar size between LGE methods: MN (2.28 ± 1.58 g) BN (2.16 ± 1.57 g) and T₁ ρ (2.29 ± 2.5 g). Confidence scores were significantly higher for BN (3.87 ± 0.346) compared with MN (3.1 ± 0.76 P < 0.001) and T₁ ρ (3.20 ± 0.71 P < 0.001).

DATA CONCLUSION

PSIR with inversion time (TI) set for blood nulling and the T₁ ρ LGE sequence demonstrated significantly higher scar to blood CNR compared with routine MN. PSIR with TI set for blood nulling demonstrated significantly higher reader confidence scores compared with routine MN and T₁ ρ LGE, suggesting routine adoption of a BN PSIR approach might be appropriate for LGE imaging.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:146-152.

Left ventricular thrombus formation in myocardial infarction is associated with altered left ventricular blood flow energetics

Aims

The main aim of this study was to characterize changes in the left ventricular (LV) blood flow kinetic energy (KE) using four-dimensional (4D) flow cardiovascular magnetic resonance imaging (CMR) in patients with myocardial infarction (MI) with/without LV thrombus (LVT).

Methods and results

This is a prospective cohort study of 108 subjects [controls = 40, MI patients without LVT (LVT- = 36), and MI patients with LVT (LVT+ = 32)]. All underwent CMR including whole-heart 4D flow. LV blood flow KE wall calculated using the formula: KE=12 ρblood . Vvoxel . v2, where ρ = density, V = volume, v = velocity, and was indexed to LV end-diastolic volume. Patient with MI had significantly lower LV KE components than controls (P < 0.05). LVT+ and LVT- patients had comparable infarct size and apical regional wall motion score (P > 0.05). The relative drop in A-wave KE from mid-ventricle to apex and the proportion of in-plane KE were higher in patients with LVT+ compared with LVT- (87 ± 9% vs. 78 ± 14%, P = 0.02; 40 ± 5% vs. 36 ± 7%, P = 0.04, respectively). The time difference of peak E-wave KE demonstrated a significant rise between the two groups (LVT-: 38 ± 38 ms vs. LVT+: 62 ± 56 ms, P = 0.04). In logistic-regression, the relative drop in A-wave KE (beta = 11.5, P = 0.002) demonstrated the strongest association with LVT.

Conclusion

Patients with MI have reduced global LV flow KE. Additionally, MI patients with LVT have significantly reduced and delayed wash-in of the LV. The relative drop of distal intra-ventricular A-wave KE, which represents the distal late-diastolic wash-in of the LV, is most strongly associated with the presence of LVT.

CMR quantitation of change in mitral regurgitation following transcatheter aortic valve replacement (TAVR): impact on left ventricular reverse remodeling and outcome

Current echocardiographic data reporting the impact of concomitant mitral regurgitation (MR) on outcome in patients who undergo transcatheter aortic valve replacement (TAVR) are conflicting. Using cardiovascular magnetic resonance (CMR) imaging, this study aimed to assess the impact of MR severity on cardiac reverse remodeling and patient outcome. 85 patients undergoing TAVR with CMR pre- and 6 m post-TAVR were evaluated. The CMR protocol included cines for left (LV) and right ventricular (RV) volumes, flow assessment, and myocardial scar assessment by late gadolinium enhancement (LGE). Patients were dichotomised according to CMR severity of MR fraction at baseline (‘non-significant’ vs ‘significant’) and followed up for a median duration of 3 years. Forty-two (49%) patients had ‘significant MR’ at baseline; they had similar LV and RV size and function compared to the ‘non-significant MR’ group but had greater LV mass at baseline. In those with significant MR at baseline, 77% (n = 32) had a reduction in MR post-TAVR, moving them into the ‘non-significant’ category at 6-months, with an overall reduction in MR fraction from 34 to 17% (p < 0.001). Improvement in MR was not associated with more favourable cardiac reverse remodeling when compared with the ‘non-improvers’. Significant MR at baseline was not associated with increased mortality at follow-up. Significant MR is common in patients undergoing TAVR and improves in the majority post-procedure. Improvement in MR was not associated with more favourable LV reverse remodeling and baseline MR severity was not associated with mortality.

Left ventricular blood flow kinetic energy after myocardial infarction - insights from 4D flow cardiovascular magnetic resonance

BACKGROUND

Myocardial infarction (MI) leads to complex changes in left ventricular (LV) haemodynamics that are linked to clinical outcomes. We hypothesize that LV blood flow kinetic energy (KE) is altered in MI and is associated with LV function and infarct characteristics. This study aimed to investigate the intra-cavity LV blood flow KE in controls and MI patients, using cardiovascular magnetic resonance (CMR) four-dimensional (4D) flow assessment.

METHODS

Forty-eight patients with MI (acute-22; chronic-26) and 20 age/gender-matched healthy controls underwent CMR which included cines and whole-heart 4D flow. Patients also received late gadolinium enhancement imaging for infarct assessment. LV blood flow KE parameters were indexed to LV end-diastolic volume and include: averaged LV, minimal, systolic, diastolic, peak E-wave and peak A-wave KEiEDV. In addition, we investigated the in-plane proportion of LV KE (%) and the time difference (TD) to peak E-wave KE propagation from base to mid-ventricle was computed. Association of LV blood flow KE parameters to LV function and infarct size were investigated in all groups.

RESULTS

LV KEiEDV was higher in controls than in MI patients (8.5 ± 3 μJ/ml versus 6.5 ± 3 μJ/ml, P = 0.02). Additionally, systolic, minimal and diastolic peak E-wave KEiEDV were lower in MI (P < 0.05). In logistic-regression analysis, systolic KEiEDV (Beta = - 0.24, P < 0.01) demonstrated the strongest association with the presence of MI. In multiple-regression analysis, infarct size was most strongly associated with in-plane KE (r = 0.5, Beta = 1.1, P < 0.01). In patients with preserved LV ejection fraction (EF), minimal and in-plane KEiEDV were reduced (P < 0.05) and time difference to peak E-wave KE propagation during diastole increased (P < 0.05) when compared to controls with normal EF.

CONCLUSIONS

Reduction in LV systolic function results in reduction in systolic flow KEiEDV. Infarct size is independently associated with the proportion of in-plane LV KE. Degree of LV impairment is associated with TD of peak E-wave KE. In patient with preserved EF post MI, LV blood flow KE mapping demonstrated significant changes in the in-plane KE, the minimal KEiEDV and the TD. These three blood flow KE parameters may offer novel methods to identify and describe this patient population.

Fully automated, inline quantification of myocardial blood flow with cardiovascular magnetic resonance: repeatability of measurements in healthy subjects

BACKGROUND

Non-invasive assessment of myocardial ischaemia is a cornerstone of the diagnosis of coronary artery disease. Measurement of myocardial blood flow (MBF) using positron emission tomography (PET) is the current reference standard for non-invasive quantification of myocardial ischaemia. Dynamic myocardial perfusion cardiovascular magnetic resonance (CMR) offers an alternative to PET and a recently developed method with automated inline perfusion mapping has shown good correlation of MBF values between CMR and PET. This study assessed the repeatability of myocardial perfusion mapping by CMR in healthy subjects.

METHODS

Forty-two healthy subjects were recruited and underwent adenosine stress and rest perfusion CMR on two visits. Scans were repeated with a minimum interval of 7 days. Intrastudy rest and stress MBF repeatability were assessed with a 15-min interval between acquisitions. Interstudy rest and stress MBF and myocardial perfusion reserve (MPR) were measured for global myocardium and regionally for coronary territories and slices.

RESULTS

There was no significant difference in intrastudy repeated global rest MBF (0.65 ± 0.13 ml/g/min vs 0.62 ± 0.12 ml/g/min, p = 0.24, repeatability coefficient (RC) =24%) or stress (2.89 ± 0.56 ml/g/min vs 2.83 ± 0.64 ml/g/min, p = 0.41, RC = 29%) MBF. No significant difference was seen in interstudy repeatability for global rest MBF (0.64 ± 0.13 ml/g/min vs 0.64 ± 0.15 ml/g/min, p = 0.80, RC = 32%), stress MBF (2.71 ± 0.61 ml/g/min vs 2.55 ± 0.57 ml/g/min, p = 0.12, RC = 33%) or MPR (4.24 ± 0.69 vs 3.73 ± 0.76, p = 0.25, RC = 36%). Regional repeatability was good for stress (RC = 30-37%) and rest MBF (RC = 32-36%) but poorer for MPR (RC = 35-43%). Within subject coefficient of variation was 8% for rest and 11% for stress within the same study, and 11% for rest and 12% for stress between studies.

CONCLUSIONS

Fully automated, inline, myocardial perfusion mapping by CMR shows good repeatability that is similar to the published PET literature. Both rest and stress MBF show better repeatability than MPR, particularly in regional analysis.

Multimodality imaging for the quantitative assessment of mitral regurgitation

The natural history of mitral regurgitation (MR) results in significant morbidity and mortality. Innovations in non-invasive imaging have provided new insights into the pathophysiology and quantification of MR, in addition to early detection of left ventricular (LV) dysfunction and prognostic assessment in asymptomatic patients. Transthoracic (TTE) and transesophageal (TOE) echocardiography are the mainstay for diagnosis, assessment and serial surveillance. However, the advance from 2D to 3D imaging leads to improved assessment and characterization of mitral valve (MV) disease. Cardiovascular magnetic resonance (CMR) is increasingly used for MR quantitation and can provide an alternative imaging method if echocardiography is suboptimal or inconclusive. Other techniques such as exercise echocardiography, tissue Doppler imaging and speckle-tracking echocardiography can further offer complementary information on prognosis. This review summarises the current evidence for state-of-the-art cardiovascular imaging for the investigation of MR. Whilst advanced echocardiographic techniques are superior in the evaluation of complex MV anatomy, CMR appears the most accurate technique for the quantification of MR severity. Integration of multimodality imaging for the assessment of MR utilises the advantages of each imaging technique and offers the most comprehensive assessment of MR.

The Prognostic Value of Heart Type Fatty Acid Binding Protein in Patients with Suspected Acute Coronary Syndrome: A Systematic Review

Background:

Heart type fatty acid protein (HFABP) is a cytosolic protein released early after acute coronary syndrome (ACS) even in the absence of myocardial necrosis.

Objectives:

The purpose of this systematic review was to determine whether HFABP levels in patients with suspected, or confirmed ACS, improve risk stratification when added to established means of risk assessment.

Methods:

We searched Medline, Pubmed and Embase databases from inception to July 2015 to identify prospective studies with suspected or confirmed ACS, who had HFABP measured during the index admission with at least 1 month follow up data. A prognostic event was defined as all-cause mortality or acute myocardial infarction (AMI).

Results:

7 trials providing data on 6935 patients fulfilled inclusion criteria. There were considerable differences between studies and this was manifest in variation in prognostic impact of elevated HFABP(Odds ratio range 1.2-15.2 for death). All studies demonstrated that HFABP provide unadjusted prognostic information and in only one study this was negated after adjusting for covariates. A combination of both negative troponin and normal HFABP conferred a very low event rate. No study evaluated the incremental value of HFABP beyond that of standard risk scores. Only one study used a high sensitive troponin assay.

Conclusion:

There was marked heterogeneity in prognostic impact of HFABP in ACS between studies reflecting differences in sampling times and population risk. Prospective studies of suspected ACS with early sampling of HFABP in the era of high sensitivity troponin are necessary to determine the clinical value of HFABP. HFABP should not currently be used clinically as a prognostic marker in patients with suspected ACS.

Extra-cellular expansion in the normal, non-infarcted myocardium is associated with worsening of regional myocardial function after acute myocardial infarction

BACKGROUND

Expansion of the myocardial extracellular volume (ECV) is a surrogate measure of focal/diffuse fibrosis and is an independent marker of prognosis in chronic heart disease. Changes in ECV may also occur after myocardial infarction, acutely because of oedema and in convalescence as part of ventricular remodelling. The objective of this study was to investigate changes in the pattern of distribution of regional (normal, infarcted and oedematous segments) and global left ventricular (LV) ECV using semi-automated methods early and late after reperfused ST-elevation myocardial infarction (STEMI).

METHODS

Fifty patients underwent cardiovascular magnetic resonance (CMR) imaging acutely (24 h-72 h) and at convalescence (3 months). The CMR protocol included: cines, T2-weighted (T2 W) imaging, pre-/post-contrast T1-maps and LGE-imaging. Using T2 W and LGE imaging on acute scans, 16-segments of the LV were categorised as normal, oedema and infarct. 800 segments (16 per-patient) were analysed for changes in ECV and wall thickening (WT).

RESULTS

From the acute studies, 325 (40.6%) segments were classified as normal, 246 (30.8%) segments as oedema and 229 (28.6%) segments as infarct. Segmental change in ECV between acute and follow-up studies (Δ ECV) was significantly different for normal, oedema and infarct segments (0.8 ± 6.5%, -1.78 ± 9%, -2.9 ± 10.9%, respectively; P < 0.001). Normal segments which demonstrated deterioration in wall thickening at follow-up showed significantly increased Δ ECV compared with normal segments with preserved wall thickening at follow up (1.82 ± 6.05% versus -0.10 ± 6.88%, P < 0.05).

CONCLUSION

Following reperfused STEMI, normal myocardium demonstrates subtle expansion of the extracellular volume at 3-month follow up. Segmental ECV expansion of normal myocardium is associated with worsening of contractile function.

The effect of carvedilol on B-type natriuretic peptide and cardiac function in patients with heart failure and persistent atrial fibrillation

OBJECTIVES

We sought to determine the relationship between changes in natriuretic peptides and symptoms as a consequence of introducing beta-blocker therapy, in patients with chronic heart failure (CHF) and persistent atrial fibrillation (AF).

METHODS

In a randomised, double-blind, placebo-controlled study involving 47 patients with CHF and persistent AF (mean age 68 years and 62% men), we analysed the individual change (Δ) in B-type natriuretic peptide (BNP) level to the introduction of carvedilol (titrated to a target dose of 25 mg twice daily, group A) or placebo (group B) in addition to background treatment with digoxin. Symptoms score, 6-min walk distance, New York Heart Association (NYHA) class, left ventricular ejection fraction (LVEF), heart rate (24-hour ECG) and BNP were measured at baseline and at 4 months.

RESULTS

LVEF (Δ median +5 vs. +0.4, p = 0.048), symptoms score (Δ median -4 vs. 0, p = 0.04), NYHA class (Δ median -33% vs. +3% in NYHA class 3-4, p = 0.046) and heart rate [Δ median 24-hour ventricular rate (VR) -19 vs. -2, p < 0.0001] improved with combination therapy of digoxin and carvedilol compared to digoxin alone, but BNP (Δ median +28 vs. -6 , p = 0.11) trended in the opposite direction. There was no relationship between the degree of symptomatic improvement or VR control and BNP response.

CONCLUSION

After the introduction of carvedilol, clinical outcome appears unrelated to BNP changes in patients with CHF and AF. Changes in BNP cannot be used as a marker of clinical response in terms of symptoms or cardiac function in this setting.