The relationship between myocardial microstructure and strain in chronic infarction using cardiovascular magnetic resonance diffusion tensor imaging and feature tracking

BACKGROUND

Cardiac diffusion tensor imaging (cDTI) using cardiovascular magnetic resonance (CMR) is a novel technique for the non-invasive assessment of myocardial microstructure. Previous studies have shown myocardial infarction to result in loss of sheetlet angularity, derived by reduced secondary eigenvector (E2A) and reduction in subendocardial cardiomyocytes, evidenced by loss of myocytes with right-handed orientation (RHM) on helix angle (HA) maps. Myocardial strain assessed using feature tracking-CMR (FT-CMR) is a sensitive marker of sub-clinical myocardial dysfunction. We sought to explore the relationship between these two techniques (strain and cDTI) in patients at 3 months following ST-elevation MI (STEMI).

METHODS

32 patients (F = 28, 60 ± 10 years) underwent 3T CMR three months after STEMI (mean interval 105 ± 17 days) with second order motion compensated (M2), free-breathing spin echo cDTI, cine gradient echo and late gadolinium enhancement (LGE) imaging. HA maps divided into left-handed HA (LHM, - 90 < HA < - 30), circumferential HA (CM, - 30° < HA < 30°), and right-handed HA (RHM, 30° < HA < 90°) were reported as relative proportions. Global and segmental analysis was undertaken.

RESULTS

Mean left ventricular ejection fraction (LVEF) was 44 ± 10% with a mean infarct size of 18 ± 12 g and a mean infarct segment LGE enhancement of 66 ± 21%. Mean global radial strain was 19 ± 6, mean global circumferential strain was - 13 ± - 3 and mean global longitudinal strain was - 10 ± - 3. Global and segmental radial strain correlated significantly with E2A in infarcted segments (p = 0.002, p = 0.011). Both global and segmental longitudinal strain correlated with RHM of infarcted segments on HA maps (p < 0.001, p = 0.003). Mean Diffusivity (MD) correlated significantly with the global infarct size (p < 0.008). When patients were categorised according to LVEF (reduced, mid-range and preserved), all cDTI parameters differed significantly between the three groups.

CONCLUSION

Change in sheetlet orientation assessed using E2A from cDTI correlates with impaired radial strain. Segments with fewer subendocardial cardiomyocytes, evidenced by a lower proportion of myocytes with right-handed orientation on HA maps, show impaired longitudinal strain. Infarct segment enhancement correlates significantly with E2A and RHM. Our data has demonstrated a link between myocardial microstructure and contractility following myocardial infarction, suggesting a potential role for CMR cDTI to clinically relevant functional impact.

Coexistent diabetes is associated with the presence of adverse phenotypic features in patients with hypertrophic cardiomyopathy

Background

Type 2 diabetes mellitus (DM) is associated with worsened clinical outcomes in hypertrophic cardiomyopathy (HCM) patients. The reasons for this adverse prognostic association are incompletely understood. Although distinct entities both HCM and DM share common features of impaired myocardial energetics and coronary microvascular function.

Purpose

We sought to test the hypothesis that co-existent diabetes is associated with greater reductions in myocardial energetics and perfusion, and higher scar burden in HCM.

Research design and methods

Seventy-five age- and sex-matched participants with concomitant HCM and DM (HCM-DM, n=20), isolated HCM (n=20), isolated DM (n=20) and healthy volunteers (HV, n=15) underwent 31phosphorus magnetic resonance spectroscopy and cardiovascular magnetic resonance imaging. The HCM groups were matched for HCM phenotype. The DM groups were matched for diabetes treatment, duration, HbA1c, body mass index and hypertension comorbidity.

Results

ESC sudden cardiac death risk scores were comparable between the HCM groups (HCM: 2.2±1.5%, HCM-DM: 1.9±1.2%; p=NS) and sarcomeric mutations were equally common. HCM-DM had the highest NT-proBNP levels (HV: 42 ng/L [IQR: 35–66], DM: 118 ng/L [IQR: 53–187], HCM: 298 ng/L [IQR: 157–837], HCM-DM: 726 ng/L [IQR: 213–8695]; p&lt;0.0001). Left-ventricular ejection fraction, mass and wall thickness were similar between the HCM groups. HCM-DM displayed a greater degree of fibrosis burden with higher scar percentage, and lower global longitudinal strain compared to the isolated HCM. PCr/ATP was similarly decreased in the HCM-DM and DM (HV: 2.17±0.49, DM: 1.61±0.23, HCM: 1.93±0.38, HCM-DM: 1.54±0.27; p=0.0003). HCM-DM had the lowest stress myocardial blood flow (HV: 2.06±0.42 ml/min/g, DM: 1.78±0.45 ml/min/g, HCM: 1.74±0.44 ml/min/g, HCM-DM: 1.39±0.42 ml/min/g; p=0.004).

Conclusions

We show for the first time that HCM patients with DM comorbidity display greater reductions in myocardial energetics, perfusion, contractile function and higher myocardial scar burden and serum NT-proBNP levels compared to patients with isolated HCM despite similar LV mass and wall thickness and presence of sarcomeric mutations. These adverse phenotypic features may be important components of the adverse clinical manifestation attributable to a combined presence of HCM and DM.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Diabetes UK

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.

Transaortic flow rate to predict short and long term outcomes in individuals with asymptomatic aortic stenosis

Background

Echocardiographic derived transaortic flow rate (TFR), defined as stroke volume over left ventricular ejection time, has been shown to be associated with increased mortality in asymptomatic mild to severe aortic stenosis (AS) and superior to stroke volume index (SVi) in individuals with symptomatic discordant AS undergoing aortic valve replacement. However, TFR has not been explored alongside SVi in asymptomatic moderate to severe AS, who are a group of interest in risk stratifying for early intervention. Moreover, there is no data where TFR is indexed to body surface area (TFRi).

Purpose

We explored the prognostic value of TFR, TFRi and SVi in a homogenous cohort of asymptomatic patients with moderate to severe AS.

Methods

Subjects with asymptomatic moderate to severe AS were prospectively recruited to the Prognostic Importance of Microvascular Dysfunction in asymptomatic patients with AS (PRIMID) study, a multi-centre observational study in the UK conducted between April 2012 and November 2014. All subjects underwent extensive phenotyping with transthoracic echocardiography, bicycle exercise testing and cardiovascular magnetic resonance (CMR) imaging, with blinded core-lab analysis. Patients were followed up in person for a minimum of 12 months, and through health records thereafter. The composite outcome of interest was: cardiovascular mortality, AVR for symptoms and major adverse cardiovascular events (hospitalisation with heart failure, myocardial infarction, syncope and arrhythmia) at one-year and at five years. A cox proportional hazards model was used to calculate a hazard ratio (HR) and 95% confidence intervals (95% CI). Known co-variables associated with the composite outcome were added into the multivariable model.

Results

Overall, 173 individuals were included with a mean age of 66.3—-±13.3 years and 76.4% were male. Most individuals had severe AS (71.1%, n=123). There were 47 (64.4%) primary outcome events at one-year and 110 (63.6%) events at five-years. Age, sex, N-terminal pro brain natriuretic peptide (NT-pro-BNP), peak aortic velocity (AV Vmax), a positive exercise tolerance test (ETT), myocardial perfusion reserve and right ventricular ejection fraction measured on cardiac magnetic resonance were included in the multivariable model in addition to TFR or TFRi or SVi. Decreasing TFR and TFRi remained independently associated with one-year and five-year composite outcome (Figure 1). However, SVi was only associated with the composite outcome at five-years. AV Vmax (HR: 4.36, 95% CI: 2.59, 7.34, p&lt;0.01) and a positive ETT (HR: 1.87, 95% CI: 1.03, 3.37, p=0.04) were independently associated with the primary outcome at one-year.

Conclusion

Both TFR and TFRi have a potential role in risk stratifying asymptomatic patients with AS and identifying those for earlier intervention, and may be superior to SVi. However, further prospectively designed studies are needed before this becomes part of the routine clinical practice.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Independent research from a Post-Doctoral Fellowship supported by the National Institute for Health Research (NIHR-PDF 2011-04-51 Geral P McCann).

Post-myocardial infarction late diastolic left ventricular blood flow energetics are independently associated with left ventricular remodeling

Background

Post-myocardial infarction (MI) left ventricular (LV) remodeling emerges as a compensatory mechanism and leads to complex pathophysiological changes in LV blood flow hemodynamics. The interplay, if any, between LV blood flow energetics and remodeling remains unknown. We hypothesized that LV blood flow energetics early after MI are independently related to the temporal changes in LV end-diastolic volume (LVEDV).

Methods

In this prospective cohort study, 69 patients with acute re-perfused ST-segment elevation MI (STEMI) were included. The patients underwent cardiovascular magnetic resonance (CMR) examination within 2 days of the index event and at 3-month. CMR examination included cine, late gadolinium enhancement, and whole-heart 4D flow acquisitions. LV volume-function, infarct size (indexed to body surface area), microvascular obstruction (MVO), mitral inflow, and 4D blood flow kinetic energy (KE) characteristics were obtained. LV mean and peak KEi (indexed to LVEDV) were quantified for all time parameters (entire cardiac cycle, during systole/diastole, at E- and A-waves).

Results

In univariable linear regression analysis, peak KEi (R-R interval), mean systolic KEi, A-wave KEi, MVO presence were all associated with the relative change (%) of LVEDV (p=0.03, p=0.01, p&lt;0.01, P=0.03, respectively). In multivariable linear regression analysis, A-wave KEi was identified as the only independent marker for association with the relative change of LVEDV (p=0.02). In another univariable linear regression analysis, A-wave KEi, infarct size, and MVO presence were all associated with the absolute change of LVEDV (p=0.03, p=0.04, p=0.04, respectively). In multivariable linear regression analysis, A-wave KEi was determined as the only independent marker for association with the absolute change of LVEDV (p=0.02). No significant association was observed between mitral inflow characteristics and relative and absolute change of LVEDV.

Conclusion

Late diastolic LV blood flow energetics early after acute MI are independently associated with both absolute and relative longitudinal changes in LVEDV and may provide incremental value over infarct and mitral inflow characteristics to be associated with post-MI LV remodeling.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): British Heart Foundation

Clinical outcomes and myocardial recovery in energetics, perfusion and contractile function after valve replacement surgery in severe aortic stenosis patients with diabetes comorbidity

Background

Aortic stenosis (AS) and type 2 diabetes mellitus (DM) are increasingly frequent comorbidities in aging populations, and diabetes is associated with increased morbidity and mortality after aortic valve replacement (AVR). Although distinct pathological entities, AS and DM share common features of impaired myocardial energetics and coronary microvascular dysfunction (CMD). The mechanisms for the adverse prognostic association between AS and DM are incompletely understood.

Purpose

Utilising 31phosphorus magnetic resonance spectroscopy (31P-MRS) and CMR, we tested the hypotheses that the collective impact of severe AS and DM on the myocardium aggravates the impairment in energetics, function and perfusion.

Methods

Eighty-eight severe AS patients with (AS-DM) and without DM (Iso-AS) undergoing AVR and 15 healthy volunteers were recruited. Patients with coronary artery disease were excluded. Participants with AS underwent 31P-MRS and comprehensive CMR imaging 1 month prior to and 6 months after AVR.

Results

Demographic, biochemical and CMR/31P-MRS data are shown in Table-1. All groups were matched for age and sex distribution, with AS groups matched for surgical scores and frailty scores. NTproBNP levels were similarly elevated in AS groups. Left ventricular (LV) volumes and ejection fraction (EF) were similar between the groups, with no significant difference in LV mass or wall thickness between the AS groups. The baseline differences in myocardial energetics, stress myocardial blood flow (MBF) and global longitudinal strain (GLS) are shown in the Figure. AS-DM patients showed greater reductions in myocardial energetics (p&lt;0.0001), global stress MBF (p&lt;0.0001) and more significant reductions in GLS (p=0.001) than the Iso-AS patients. At 6 month post AVR both AS groups showed significant improvements in stress MBF and GLS. However, only the Iso-AS patients showed significant improvement in myocardial energetics.

AS patients were followed up for a median of 12 months. Cumulative incidence of the clinical events post AVR (composite of cardiovascular death, stroke, heart failure admission, infective endocarditis) were significantly higher in the AS-DM group than the Iso-AS group (Hazard Ratio: 3.35; 95% CI: 0.97–11.6; p=0.02).

Conclusion

Diabetes was associated with increased morbidity and mortality after AVR. We showed for the first time that the collective impact of T2DM and AS on the myocardium aggravates energetic impairment, CMD and contractile dysfunction. While myocardial recovery following AVR was associated with similar improvements in perfusion and contractile function in severe AS patients with and without T2DM, improvements in energetics were only detected in isolated AS patients. However, despite the significant improvements in contractile function and perfusion following AVR in diabetes patients, these parameters remained lower in the group with diabetes comorbidity compared to isolated AS patients.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Wellcome Trust

Gestational diabetes, preeclampsia and the maternal heart

Background

Gestational diabetes mellitus (GDM) and preeclampsia (pE) are both associated with an increased risk of cardiovascular mortality and morbidity, including an increased risk of developing heart failure in later life. Both conditions are increasing in prevalence; GDM affects up to 12% and pE affects 3–5% of pregnancies worldwide. Compromised cardiac energy production is an important contributor to most forms of heart disease. The changes in myocardial energetics in GDM and pE have not been characterised previously.

Purpose

We sought to assess if women with GDM and women with pE in the third trimester of pregnancy exhibit adverse cardiac alterations in myocardial energetics, function or tissue characteristics.

Methods

Thirty-eight healthy pregnant (HP) women, thirty women with GDM and fifteen women with pE were recruited, matched for age and ethnicity. Participants underwent phosphorus magnetic resonance spectroscopy and cardiovascular magnetic resonance for assessment of myocardial energetics (phosphocreatine to ATP ratio (PCr/ATP)), tissue characteristics, biventricular volumes and ejection fractions, left ventricular (LV) mass, global longitudinal strain (GLS) and mitral in-flow E/A ratio.

Results

The biochemical characteristics and multiparametric MR results are given in Table 1.

The women in the GDM and the pE groups had higher body-mass index. There was a stepwise increase in the systolic and diastolic BP from the HP to the GDM to the pE group. There was no difference in NTproBNP concentrations between the groups. The gestational weight gain was higher in women with GDM and pE compared to the HP group.

The women in the GDM and the pE groups showed similar reductions in myocardial PCr/ATP ratios compared to HP group (Figure 1a), accompanied by lower LV end-diastolic volumes and higher LV mass (Figure 1b) and enhanced LV concentricity in both groups (Figure 1c). While LV ejection fractions were similar across the groups, the GLS was reduced in women with GDM and in women with pE (Figure 1d).

Conclusions

We show here for the first time that despite no prior diagnosis of diabetes or hypertension, women with GDM or pE manifest impaired myocardial contractility and higher LV mass, associated with reductions in myocardial energetics. These findings may aid our understanding of the long-term cardiovascular risks associated with these conditions.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Wellcome Trust

Evaluation of cardiac involvement in patients with clinical post-COVID-19 syndrome

Introduction

The underlying pathophysiology of Post-COVID-19 syndrome remains unknown, but increased cardiometabolic demand and state of mitochondrial dysfunction have emerged as candidate mechanisms. Cardiovascular magnetic resonance (CMR) provides insight into pathophysiological mechanisms underlying cardiovascular disease and 31-phosphorus magnetic resonance spectroscopy (31P-MRS) allows non-invasive assessment of the myocardial energetic state.

Purpose

We sought to assess whether Post-COVID-19 syndrome is associated with abnormalities of myocardial structure, function, perfusion and tissue characteristics or energetic derangement.

Methods

Prospective case-control study. A total of 20 patients with a clinical diagnosis of Post-COVID-19 syndrome (seropositive) and no prior underlying cardiovascular disease (CVD) and ten matching controls underwent 31P-MRS and CMR at 3T at a single time point. (Figure 1) All patients had been symptomatic with acute COVID-19, but none required hospital admission.

Results

Between the Post-COVID-19 syndrome patients and matched contemporary controls there were no differences in myocardial energetics (phosphocreatine to ATP ratio), in cardiac structure (biventricular volumes, left ventricular mass), function (biventricular ejection fractions, global longitudinal strain), tissue characterization (T1 and extracellular volume [ECV] fraction mapping, late gadolinium enhancement) or perfusion (myocardial rest and stress blood flow, myocardial perfusion reserve). One patient with Post-COVID-19 syndrome showed subepicardial hyperenhancement on the late gadolinium enhancement imaging compatible with prior myocarditis, but no accompanying abnormality in cardiac size, function, perfusion, ECV, T1, T2 mapping or energetics. This patient was excluded from statistical analyses. (Table 1)

Conclusion

In this study, the overwhelming majority of patients with a clinical Post-COVID-19 syndrome with no prior CVD did not exhibit any abnormalities in myocardial energetics, structure, function, blood flow or tissue characteristics.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Welcome Trust Clinical Career Development Fellowship (221690/Z/20/Z);NIHR-UKRI COVID-19 Rapid Response Rolling Call (COV0254)ESC Training Grant

The effect of COVID-19 on training in cardiology: a survey of UK cardiology trainees

Background

The COVID-19 pandemic has had an unprecedented impact on delivering cardiology services. In the UK and many other countries, cardiologists in training were redeployed to other services. To date, the impact of COVID-19 and the requisite NHS response on cardiology training has been unclear.

Purpose

To assess the impact of the COVID-19 pandemic on cardiology training in the UK.

Methods

An annual survey of UK cardiology trainees was conducted through the national trainee organisation. In 2021, trainees were asked questions regarding their training experience, procedural exposure, and how they had been impacted by COVID-19. Reported procedural numbers were compared with those reported in 2017–2019. Chi squared analyses were used to compare categorical variables with Mann-Whitney U tests used for continuous variables.

Results

A total of 576 trainees completed the survey (70% male, mean age 33±3 years). Of 545 respondents who detailed the impact of COVID-19 on training opportunities, 70.5% (n=384) reported a negative or very negative impact. A similar picture was seen when asked about procedure, diagnostic, and outpatient training opportunities (Figure 1). Those completing core cardiology training in 2021 reported performing significantly fewer coronary angiograms (median 170, IQR 85–315) compared with those completing core cardiology training 2017–2019 (median 285, IQR 165–460, p<0.001).

Fifty percent of trainees (n=285) reported being redeployed for a median duration of 4 months (IQR 3–5 months). There was substantial regional variation in both the proportion of trainees redeployed (Figure 2, p<0.001) and the median length of redeployment (p=0.008). Those redeployed were more likely to report negative training experiences as a result of COVID-19 (p<0.001). Redeployed trainees completing core cardiology training in 2021 reported undertaking significantly fewer echocardiograms (median 205, IQR 100–300) compared with those not redeployed (median 280, IQR 200–300, p=0.01). Thirty-five percent of all trainees reported being close to burnout, with redeployed trainees being more likely to feel this way (p<0.001). When asked about methods to redress lost training opportunities, 37% of trainees wanted to prolong their training time with a median of 6 months felt to be required (IQR 6–8 months).

Discussion

This large survey of the UK experience illustrates the substantial negative impact of COVID-19 on the quality of cardiology training. Redeployment alone resulted in an estimated 95 person-years of lost training time. Coordinated national and regional strategies are required to avoid the creation of a generation of under-trained consultant cardiologists.

Funding Acknowledgement

Type of funding sources: None.

Left ventricular blood flow energetics after acute ST-segment elevation myocardial infarction associate with left ventricular remodeling

Background

Myocardial infarction (MI) leads to complex changes in left ventricular (LV) haemodynamics. It remains unknown how four-dimensional (4D) acute changes in LV blood flow kinetic energy (KE) affect LV remodeling. We hypothesized that LV blood flow energetics are independently associated with adverse LV-remodeling.

Methods

In total, 69 revascularised ST-segment elevation MI patients were enrolled. All patients underwent cardiovascular magnetic resonance (CMR) examination within 2 days of the index event and at 3-month. CMR examination included cine, late gadolinium enhancement, and whole-heart 4D flow acquisitions. CMR analysis included: LV volumes, function, infarct size (indexed to body surface area), microvascular obstruction (MVO), two-dimensional, retrospective valve tracking derived mitral inflow metrics, and 4D blood flow KE components (Fig. 1). Adverse LV-remodeling was defined and categorized according to increase in LV end-diastolic volume: 10% (mild), 15% (moderate), and 20% (severe).

Results

Twenty-four patients (35%) developed mild, 17 patients (25%) moderate, 11 patients (16%) severe LV remodeling. Demographics and clinical history were comparable between patients with/without LV remodeling. In univariable logistic regression analysis, A-wave KE was associated with mild, moderate, and severe LV remodeling (p=0.03, p=0.02, p=0.02, respectively), whereas infarct size was associated with only mild LV remodeling (p=0.02). In multivariable logistic regression analysis, whilst the infarct size and A-wave KE were identified as independent markers for mild LV remodeling (p=0.03, p=0.09, respectively), A-wave KE was the only independent marker regarding moderate and severe LV remodeling (both, p&lt;0.01). In ROC analysis for A-wave KE to be associated with the presence of adverse LV remodeling, the area under the curve was 0.67 for mild (p=0.02), 0.70 for moderate (p=0.01), 0.71 for severe (p=0.03) LV remodeling.

Conclusion

In patients with STEMI, LV hemodynamics assessment by LV blood flow KE demonstrated an incremental value to predict adverse LV-remodeling. A-wave KE early after acute MI had an independent effect on adverse LV remodeling.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): This work was supported by the British Heart Foundation [FS/10/62/28409 to S.P.] and Dutch Technology Foundation (STW), project number 11626 (JW, ME).

Coronary microvascular dysfunction is only detectable in type 2 diabetes in the presence of obesity

Background

Heart failure (HF) is a leading cardiovascular complication of type 2 diabetes (T2D). Coronary microvascular dysfunction (CMD) precedes HF in diabetes and carries important prognostic information. CMD is also evident in metabolically healthy obese individuals without diabetes or hypertension. Whether diabetes causes CMD in the absence of obesity is uncertain. The interrelation among visceral adiposity and CMD has not been assessed previously.

Objectives

We sought to better understand the links between visceral and epicardial adipose tissue (VAT and EAT respectively) distribution, insulin resistance with myocardial perfusion, energetics and function in asymptomatic lean (LnT2D) and overweight/obese T2D patients (ObT2D) without cardiovascular disease.

Methods

62 participants [27 Ob-T2D, 15 Ln-T2D, and 20 overweight controls] were recruited. Subjects underwent cardiac and abdominal magnetic resonance imaging and 31P-magnetic resonance spectroscopy, for measurements of EAT and VAT areas, rest and adenosine stress myocardial blood flow (MBF), cardiac function and phosphocreatine to ATP ratio (PCr/ATP). Fasting blood samples were taken for plasma homeostasis model assessment of insulin resistance (HOMA-IR) index calculations.

Results

The biochemical characteristics and multiparametric MR results are given in Table 1 and results of Pearson's regression analysis in the entire study population are given in Table 2.

Stress MBF was lowest in ObT2D, while rest MBF was highest in LnT2D. Left ventricular ejection fraction (LVEF) and myocardial PCr/ATP were similarly reduced in diabetes groups. In the absence of obesity, there was no significant increase in VAT, EAT or HOMA-IR in T2D patients compared to controls. BMI and VAT, negatively correlated with LVEF, and strain parameters. PCr/ATP correlated with LVEF, but not HOMA-IR. BMI, EAT and VAT all correlated significantly with HOMA-IR, and HOMA-IR correlated with cardiac functional parameters. There was no association between HOMA-IR and myocardial perfusion.

Conclusions

In this study CMD was only evident in ObT2D patients, with normal rest and stress MBF in LnT2D patients. Despite normal perfusion and no significant increase in insulin resistance, LVEF and myocardial PCr/ATP were similarly reduced in LnT2D and ObT2D, and PCr/ATP correlated with LVEF. This suggests that alterations in cardiac energy metabolism are mechanistically more relevant for the pathophysiology of diabetic cardiomyopathy in LnT2D patients. In the absence of correlation between insulin resistance and myocardial perfusion, factors like inflammation and altered adipokine profile may play important roles for the pathophysiology of CMD in ObT2D patients. A better understanding of the underlying pathophysiological mechanisms of diabetic cardiomyopathy in LnT2D and ObT2D may help to develop contemporary tailored treatment and prevention strategies to tackle excess heart failure risk.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): BHFWellcome trust Table 1Table 2

Mechanistic insights from a multiparametric magnetic resonance imaging study regarding the role of sodium glucose co-transporter 2 inhibitors

Background

Type 2 diabetes (T2D) is associated with an increased risk of heart failure (HF) and cardiovascular (CV) mortality. Sodium–glucose-co transporter-2 (SGLT2) inhibitors reduce the risk of major adverse CV events and hospitalisation for HF in T2D patients with high cardiovascular risk, despite only a modest improvement in glycemic control. Restoring cellular energy homeostasis and reversing adverse cardiac remodelling in diabetes have been speculated as a potential metabolic modulatory effect of SGLT2 inhibitors leading to their beneficial CV outcomes. Myocardial energy deficient states can be detected non-invasively by 31-phosphorus magnetic resonance spectroscopy (31P-MRS).

Objectives

Utilising cardiovascular magnetic resonance imaging (CMR) and 31P-MRS in a single centre longitudinal cohort study, we aimed to investigate the effects of the selective SGLT2 inhibitor empagliflozin on myocardial energetics, function, perfusion, and myocardial cellular volume in patients with T2D.

Methods

Eighteen consecutive T2D patients who were commenced on empagliflozin in cardiometabolic optimisation clinics underwent CMR and 31P-MRS scans before and after twelve-week empagliflozin treatment, and plasma N-terminal pro hormone B-type natriuretic peptide (NT-proBNP) levels were measured. Ten controls with no diabetes underwent an identical 31P-MRS and CMR protocol on a single visit.

Results

When compared to controls, patients with T2D showed: lower myocardial energetics (1.52±0.40 vs 2.20±0.5, p=0.0005), lower stress myocardial blood flow (1.60±0.50 vs 2.10±0.50, p=0.02) and lower left ventricular ejection fraction (52±13% vs 63±4%, p=0.01). Treatment with empagliflozin led to significant improvements in myocardial energetics (PCr/ATP: 1.52 to 1.76, p=0.009). This was accompanied by a relative 13% improvement in left ventricular ejection fraction (p=0.001), 3% improvement in global longitudinal strain (p=0.01), 61% reduction in NTproBNP (p=0.05), and 9% reduction in myocardial cell volume (p=0.04). No significant change in myocardial blood flow or diastolic strain was detected.

Conclusions

For the first time, we demonstrate that empagliflizon improves myocardial energetics and function, reduces myocardial cellular volume, and reduces NT-proBNP levels in patients with T2D.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): British Heart Foundation PCr/ATPLVEF

Effect of low dose intracoronary alteplase on global circumferential strain (myocardial strain CMR substudy from the T-TIME trial)

Background

Microvascular obstruction affects half of patients with ST-segment elevation myocardial infarction (STEMI) and confers an adverse prognosis. Feature-tracking (FT) cardiac magnetic resonance (CMR) allows myocardial strain assessment from standard cine images without the need for specialist sequences. Myocardial strain reflects both systolic and diastolic function allowing the assessment of both global and regional myocardial deformation. Strain recovery is impaired in patients with microvascular obstruction. There is growing evidence to suggest that global circumferential strain may offer incremental value beyond traditional CMR endpoints.

Purpose

We aimed to determine whether a therapeutic strategy involving low-dose intracoronary alteplase improves global circumferential strain in STEMI.

Methods

Between March 17, 2016, and December 21, 2017, 440 patients presenting at 11 hospitals in the United Kingdom within 6 hours of STEMI were randomised in a 1:1:1 dose-ranging trial design. Participants were randomly assigned to treatment with placebo (n=151), alteplase 10mg (n=144), or alteplase 20mg (n=145). The primary outcome was the amount of microvascular obstruction (%left ventricular mass) quantified by CMR at 2–7 days. Global circumferential strain was a prespecified secondary endpoint measured at 2–7 days and 3 months. Troponin T AUC was measured at 0, 2, and 24 hours post reperfusion. Patients were followed up to 1 year with all events adjudicated by an independent committee.

Results

Among the 440 patients who were randomised (mean age 60.5 years; 85% male), the primary endpoint was achieved in 396 (90%), all patients were followed up to 1 year for clinical events. The amount (mean, standard deviation) of microvascular obstruction was not different between the groups (2.3% vs. 2.6% vs. 3.5% left ventricular mass); p=0.28. Global circumferential strain was worse in patients receiving alteplase. −23.1% (placebo) vs −20.6 (10mg alteplase) vs −22.0% (20mg alteplase); mean difference for both doses combined vs placebo: 1.8% (95% CI 0.5, 3.2), p=0.009. There were no differences between groups in the other CMR endpoints including LV ejection fraction (LVEF). The area-under-the-curve for troponin T measured in 317 (72%) patients was increased in both treatment groups compared to placebo, mean difference 1.53 (95% CI: 1.16, 2.01), p=0.002. There were no differences in MACE at 1 year; placebo n=16 (10.6%), 10mg alteplase n=22 (15.3%), 20mg alteplase group n=15 (10.3%).

Conclusion

In patients presenting within 6 hours of STEMI, low-dose intracoronary alteplase compared with placebo did not reduce microvascular obstruction. There was a reduction in global circumferential strain and an increase in Troponin T AUC supporting an increase in myocardial injury early after reperfusion in patients receiving alteplase. There was no differences in MACE at one year suggesting no long-term clinical sequelae.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): T-TIME was supported by grant 12/170/4 from the Efficacy and Mechanism Evaluation (EME) programme of the National Institute for Health Research (NIHR-EME). Boehringer-Ingelheim U.K. Ltd. provided the study drugs (alteplase 10mg, 20mg), matched placebo, and sterile water for injection. Study recruitment flowchartTable- Study endpoints

Microstructural characteristics of chronic infarct segments assessed using diffusion tensor imaging

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): British Heart Foundation

Background

The microstructural changes following myocardial infarction (MI) can be characterised in-vivo with cardiac diffusion tensor imaging (cDTI) imaging, using mean diffusivity (MD), fractional anisotropy (FA), secondary eigenvector angle (E2A) and helix angle (HA) maps. In this study, we use cDTI to explore the microstructural differences between subendocardial and transmural chronic infarct segments.

Method

Twenty STEMI patients (15 men, 5 women, mean age 59) underwent 3T CMR scan at 3 months following presentation (mean interval 107 ± 18 days). Scan protocol included: second order motion compensated (M012) free-breathing spin echo DTI (3 slices, 18 diffusion directions at b-values 100s/mm2[3], 200s/mm2[3] and 500s/mm2[12], acquired resolution was 2.20x2.27x8mm3; cine gradient echo and LGE imaging. Average MD, FA, E2A and HA parameters were calculated on a 16-AHA-segmental level. HA maps were described by dividing values into left-handed HA (LHM, -90° &lt; HA &lt; -30°), circumferential HA (CM, -30° &lt; HA &lt; 30°), and right-handed HA (RHM, 30° &lt; HA &lt; 90°) and reported as relative proportions. Infarct segments were identified using LGE; patients were categorised according to the maximal transmurality of their infarct segments, into subendocardial (&lt;50% LGE) or transmural (&gt;50% LGE) MI.

Results

DTI acquisition was successful in all patients (acquisition time 13 ± 5mins). Ten patients had transmural MI. The results are shown in table 1. Transmurally infarcted segments had significantly lower FA (FA subendocardial MI = 0.27 ± 0.04, FA transmural MI = 0.23 ± 0.02, p &lt; 0.01), lower E2A (E2A subendocardial MI = 47 ± 7°, E2A transmural MI = 38 ± 6°, p &lt; 0.01) and lower proportions of right-handed cardiomyocytes (RHM subendocardial MI = 21 ± 5%, RHM transmural MI = 14 ± 5%, p &lt; 0.01) than subendocardial infarct segments. 

Conclusion

Compared to subendocardial MI segments, the diffusion of water molecules is more isotropic in transmurally infarcted myocardium as evidenced by lower FA values, signifying increased structural disarray. The significantly lower E2A values suggest that laminar sheetlets of transmural infarct segments remain fixed at shallower angles during systole and are unable to reach their usual contractile configuration. The lower proportions of RHM on HA maps highlight the significantly greater loss of subendocardial cardiomyocytes in transmural infarct segments. Further studies are required to assess if these segmental changes can be predictive of long-term LV remodelling.

Left ventricular four-dimensional blood flow energetics and vorticity in chronic myocardial infarction patients with/without left ventricular thrombus

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): The British Heart Foundation [FS/10/62/28409] and Dutch ZonMw [104003001].

Background

Left ventricular thrombus (LVT) formation is a frequent and serious complication of myocardial infarction (MI). How global LV flow characteristics are related to this phenomenon is yet uncertain. In this study, we investigated LV flow differences using 4D flow cardiovascular magnetic resonance (CMR) between chronic MI patients with LVT [MI-LVT(+)] and without LVT [MI-LVT(-)], and healthy controls.

Methods

In this prospective cohort study, the 4D flow CMR data were acquired in 19 chronic MI patients (MI-LVT(+), n= 9 and MI-LVT(-), n= 10) and 9 age-matched controls. All included subjects were in sinus rhythm. The following LV flow parameters were obtained: LV flow components (direct, retained, delayed, residual), mean and peak KE values (indexed to instantaneous LV volume), mean and peak vorticity values, and diastolic vortex ring properties (position, orientation, shape).

Results

The MI patients demonstrated a significantly larger amount of delayed and residual flow, and a smaller amount of direct flow compared to controls (p = 0.02, p = 0.03, and p &lt; 0.001, respectively). The MI-LVT(+) patients demonstrated numerically increased residual flow and reduced retained and direct flow in comparison to MI-LVT(-) patients. Systolic mean and peak LV blood flow KE values were significantly lower in MI patients compared to controls (p = 0.04, p = 0.03, respectively). Overall, the mean and peak LV vorticity values were significantly lower in MI patients compared to controls. The mean vorticity at the basal level was significantly higher in MI-LVT(+) than in MI-LVT(-) patients (p &lt; 0.01). The vortex ring core during E-wave in MI-LVT(-) group was located closer to the mitral annulus and in a less tilted orientation to the LV compared to MI-LVT(+) group (p = 0.05, p &lt; 0.01, respectively).

Conclusion

Chronic MI patients with LVT express a different distribution of LV flow components, irregular vorticity vector fields, and altered diastolic vortex ring geometric properties as assessed by 4D flow CMR. Larger prospective studies are warranted to further evaluate these initial observations.

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.

Unilateral branch pulmonary artery stenting in tetralogy of fallot improves ventricular function

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): NIHR

Background

Pulmonary artery stenosis (PAS) occurs commonly in patients with tetralogy of fallot (ToF). Cardiac function and especially left ventricular longitudinal strain has been identified as an important prognostic factor for long term survival in ToF. The clinical relevance of unilateral PAS to long-term bi-ventricular function is poorly understood.

Purpose

We sought to evaluate the effect of resolving unilateral pulmonary artery obstruction on right and left ventricular performance.

Methods

We prospectively included 40 patients with TOF between 2016 and 2020, 20 who underwent unilateral PAS stenting and as comparison 20 who underwent surgical pulmonary valve replacement (PVR). MRI data was acquired during routine clinical care before and around 6-12 months after the procedure. 4 PAS patients attended additional research scans acquiring ventricular 4D flow MRI data. 4D flow MRI data was compared to the average kinetic energy curve of 10 age-matched healthy volunteers.

Results

Of the 20 patients undergoing PAS, 2 also underwent percutaneous PVR and were excluded from the comparison analysis. All patients in the PAs group showed an improvement in branch PA flow differential post procedure. Patients undergoing PAS were younger than those undergoing PVR (median 12 vs 19 years, p &lt; 0.001). Other baseline anatomical and functional parameters including right ventricular (RV) volume indexed to body surface are (RVEDV/BSA) were comparable (pre PAS median 151 [122,170] vs pre PVR 162 [140,191]; p = 0.217). While in the PVR group the right ventricular volumes reduced in both end-diastole and end-systole, in the PAS group RV function improved due to reduced end-systolic volume with largely stable end-diastolic volumes.

Changes in the left ventricle (LV) were even more interesting. In the PVR group ejection fraction improved due to an increase in end-diastolic volume with no improvement in ventricular longitudinal strain. In contrast, in the PAS group LV ejection fraction improved by a reduction in end-systolic volume and the PAS group showed a small but significant improvement in LV longitudinal strain. In addition, ¾ patients undergoing 4D flow MRI assessment showed LV kinetic energy curve more similar to the healthy volunteer averaged  LV kinetic energy curve after PAS. The 4th patient already had a near normal LV kinetic energy curve prior to PAS.

Conclusion

Unilateral PAS does not alter RV end-diastolic volumes but improves RV function. LV ejection fraction improvement is similar to that seen after PVR, but importantly PAS also improved LV longitudinal strain. This suggests that PAS might positively influence long term morbidity and mortality risk in ToF patients, but a larger multi-centre long term follow-up study is needed to confirm this.

The relationship between myocardial microstructure and strain in chronic infarcts, assessed using diffusion tensor imaging and feature tracking

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): British Heart Foundation

Background

Cardiac diffusion tensor imaging (cDTI) is a novel technique for the non-invasive assessment of myocardial microstructure.  It allows in-vivo characterisation of microstructural changes post myocardial infarction (MI). Previously published evidence shows significant loss of sheetlet orientation as derived by cDTI secondary eigenvector (E2A), and loss of subendocardial cardiomyocytes derived by reductions in the proportions of myocytes with right-handed orientation (RHM) on helix angle (HA) maps. The assessment of myocardial strain by feature tracking (FT) allows the measurement of radial strain (RS), thought to be driven by the dynamic reorientation of laminar sheetlets, and longitudinal strain (LS), which is thought to relate to subendocardial function. We sought to explore the relationship between the strain and cDTI parameters in patients at 3 months following ST-elevation MI (STEMI).

Methods

Twenty five STEMI patients (M:F = 18:7, mean age 58 ± 9) underwent 3T CMR scan (mean interval 106 ± 17 days) with the following protocol: second order motion compensated (M2), free-breathing spin echo DTI (3 slices, 18 diffusion directions at b-values 100s/mm2, 200s/mm2 and 500s/mm2, acquired resolution was 2.20*2.27*8mm3; cine gradient echo and Late Gadolinium Enhancement (LGE) imaging. HA maps were described by dividing values into left-handed HA (LHM, -90&lt; HA &lt; -30), circumferential HA (CM, -30° &lt; HA &lt; 30°), and right-handed HA (RHM, 30° &lt; HA &lt; 90°) and reported as relative proportions. Segmental analysis were undertaken to derive: HA proportions, E2A, longitudinal strain and LGE%. Segments positive for LGE were classed as infarct segments.

Results

cDTI acquisition was successful in all patients (acquisition time 13 ± 5mins). Mean ejection fraction was 47 ± 8% with mean LGE in the infarcted segment of 57 ± 27%. Mean radial strain was 21 (95% confidence interval, 15-26). The mean E2A was 44 (95% confidence interval 41-47). There was a significant correlation between segmental radial strain and segmental E2A in infarcted segments (p &lt; 0.001, figure 1). In addition, segmental longitudinal strain correlated with the proportion of RHM on HA maps (p &lt; 0.02, figure 2).

Conclusion

Through the combined use of cDTI and FT in patients with chronic infarcts, our results show that the loss of sheetlet orientation assessed using E2A, correlates with worsening radial strain. Segments with less subendocardial cardiomyocytes, evidenced by a lower proportion of myocytes with right-handed orientation on HA maps, correlated with worse longitudinal strain. While this could potentially elucidate the complex association between myocardial microstructure and regional function, further studies are needed to define the incremental clinical value of cDTI.

Prospective longitudinal characterisation of the relationship between diabetes and cardiac remodeling

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): British Heart Foundation Clinical Research Training Fellowship and Wellcome Trust

Background

Cardiovascular disease represents the primary cause of death in patients with type 2 diabetes (T2D). Heart failure (HF) is the commonest initial presentation of cardiovascular disease in T2D. Development of HF in patients with T2D is associated with a 4 to 6-fold increase in mortality, making the prevention of cardiac dysfunction an important goal. The long-term impact of T2D on cardiac function in the absence of cardiovascular disease is unknown. This is the first prospective longitudinal study utilising cardiovascular magnetic resonance (CMR) to evaluate the impact of T2D on cardiac remodeling.

Objectives

To determine longitudinal changes in the phenotypic expression of heart disease in diabetes over 6 years, and examine the association of baseline blood and imaging biomarkers with remodeling over time in patients who remained free of cardiovascular/clinical events, and to report clinical outcomes in the entire cohort.

Methods

100 asymptomatic T2D patients with no history of cardiovascular disease or hypertension were previously studied. Biventricular volumes, function, and myocardial strain were assessed by CMR and blood biomarkers taken. 6-year follow-up CMR was repeated in those without interim cardiovascular events.

Results

Of the 100 patients, 78 could be contacted for follow-up. 29 participants experienced cardiovascular/clinical events over 6 years. 32 patients who were asymptomatic and without events received follow-up CMR. The major adverse cardiovascular event rate (MI, angina, revascularisation, stroke, death) during the 6-year follow-up period, including the patients with a silent MI, amounted to 25% in this study with an overall clinical event rate of 35%.

 There were no significant changes in BP, BMI or HBA1c between baseline and follow-up (Table 1). Left ventricular end-diastolic-volume(p = 0.005), mass (p = 0.01), ejection fraction (p = 0.0001), and right ventricular end-diastolic-volume(p = 0.03) and ejection fraction(p = 0.003) reduced over time (Figure 2 and Table 1). Baseline plasma high-sensitivity cardiac-troponin-T (hs-cTnT) (R=-0.44; p = 0.01) was significantly associated with change in left ventricular ejection fraction over time.

Conclusions

Even in the absence of overt clinical CAD, significant valvular disease, uncontrolled hypertension or change in BMI, T2D results in significant reductions in cardiac size and biventricular systolic function over time. The major adverse cardiovascular event rate (MI, angina, revascularisation, stroke, death) during the 6-year follow-up period was high in diabetes patients (25%). Plasma biomarker hs-cTnT measured at baseline was associated with change in LV systolic function over the 6-year follow-up period. hs-cTnT could potentially have a significant utility as a risk-predicting tool for cardiac dysfunction in T2D patients.

Quantification of mitral regurgitation and biventricular assessment is feasible during continuous supine exercise cardiovascular magnetic resonance in primary mitral regurgitation patients

Funding Acknowledgements

Type of funding sources: None.

Background

Biventricular volume and great vessel flow assessment during continuous supine free-breathing exercise cardiovascular magnetic resonance (Ex-CMR) is feasible in healthy volunteers using Compressed SENSEx3 (CS3) sequences1. Exercise transthoracic echocardiography (TTE) provides prognostic information in primary mitral regurgitation (MR). Resting CMR offers reference standard biventricular assessment and MR quantification with superior reproducibility to TTE. Ex-CMR assessment of biventricular volumes and quantitated MR may offer additional prognostic information.

Purpose

Determine the feasibility of biventricular assessment and MR quantification in primary MR patients during continuous supine Ex-CMR using the recently validated protocol1.

Methods

10 asymptomatic patients with at least moderate primary MR on TTE (8 male, median age 62, 55-67years interquartile range) underwent continuous in-scanner (1.5T Philips Ingenia) supine cycle ergometer (Lode BV) Ex-CMR. Target heart rates (THR) were individually prescribed using heart rate reserve (HRR) and age predicted maximal heart rate model. Participants exercised for 2-minutes at no resistance, then an increase of 25-Watts every 2-minutes until THR achieved at low (30-39% HRR), then moderate (40-59% HRR) stages. CMR imaging: free-breathing CS3 respiratory navigated short axis cine imaging and free-breathing CS3 aortic phase-contrast magnetic-resonance at rest, low and moderate exercise stages. MR was quantified indirectly from left ventricular (LV) and aortic stroke volumes. Intra/inter-observer reproducibility was assessed by coefficient of variance (CV).

Results

All patients completed the Ex-CMR protocol without complication. During exercise, no statistically significant changes occurred in LV volumes, global left ventricular ejection fraction (LVEF), right ventricular end-diastolic or systolic volumes (Table 1). From rest to low and moderate exercise: right ventricular ejection fraction increased (55 ± 5.4% to 60 ± 6.0% and 63 ± 6.6% respectively, p = 0.001) and MR fraction decreased (40 ± 14% to 36 ± 11% and 30 ± 15% respectively, p = 0.006) allowing effective forward LVEF (aortic stroke volume/ left ventricular end-diastolic volume) to increase (38 ± 9.3% to 43 ± 9.3% and 46 ± 11% respectively, p = 0.004). Intra-observer reproducibility (Table 2) was excellent (CV &lt;10%), except right ventricular stroke volumes (RVSV) during low, MR volumes and fraction during moderate and right ventricular end-systolic volumes (RVESV) during both exercise stages, which were good (CV10-20%). Inter-observer reproducibility (Table 2) was excellent (CV &lt; 10%), except RVESV and MR volumes at all stages, LV end-systolic volumes during low and MR fraction during moderate exercise, which were good (CV 10-20%).

Conclusion

Biventricular assessment and MR quantification during continuous supine Ex-CMR is feasible in asymptomatic primary MR patients, further research assessing the techniques prognostic ability is now warranted.

Prevalence, predictors and outcomes of thyroid dysfunction in patients with acute myocardial infarction: the ThyrAMI-1 study

PURPOSE

Thyroid dysfunction in patients with cardiac disease is associated with worse outcomes. This study aimed to evaluate the prevalence and analyse predictors and outcomes of thyroid dysfunction in patients presenting with an acute myocardial infarction (AMI).

METHODS

A prospective multicentre observational study of patients recruited from six acute hospitals within the North of England. Consecutive patients without previous thyroid disease presenting with both ST-elevation AMI (STEMI) and non-ST-elevation AMI (NSTEMI) were recruited to the Thyroxine in Acute Myocardial Infarction 1 (ThyrAMI-1) cohort study between December 2014 and 2016. Thyroid profile, standard biochemistry measurements and demographic information were obtained within 12 h of admission to hospital. Multivariable logistic regression analyses were performed to assess the predictors of thyroid dysfunction and Cox proportional hazards analyses were utilised to compare all-cause mortality by categories of thyroid dysfunction up to June 2019.

RESULTS

Of the 1802 participants analysed, 1440 (79.9%) were euthyroid, 312 (17.3%) had subclinical hypothyroidism (SCH), 22 (1.2%) had subclinical hyperthyroidism (SHyper) and 25 (1.3%) had low T3 syndrome (LT3S). Predictors for SCH were increasing age, female sex, higher thyroid peroxidase antibody (TPOAb) levels, higher serum creatinine levels and early morning sampling time (between 00:01-06:00 h). The predictors of SHyper were lower body mass index and afternoon sampling time (between 12:01 and 18:00 h). Predictors of LT3S were increasing age, higher creatinine levels and presence of previous ischaemic heart disease. Compared to the euthyroid group, patients with LT3S had higher all-cause mortality; adjusted hazard ratio (95% CI) of 2.02 (1.03-3.95), p = 0.04, whereas those with SCH and SHyper did not exhibit significantly increased mortality; adjusted hazard ratios (95% CI) of 1.05 (0.74-1.49), p = 0.79 and 0.27 (0.04-1.95), p = 0.19, respectively.

CONCLUSIONS

Thyroid dysfunction is common in AMI patients on admission to hospital and our data provide an understanding regarding which factors might influence thyroid dysfunction in these patients. Furthermore, the negative association between LT3S and increased mortality post-AMI has once again been highlighted by this study. More research is required to assess if treatment of thyroid dysfunction improves clinical outcomes.

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

Longitudinal change in left ventricular 4D flow kinetic energy after myocardial infarction

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): British Heart Foundation HRUK

Background. Four-dimensional flow (4D flow) cardiovascular magnetic resonance (CMR) imaging provides quantification of intra-cavity left ventricular (LV) flow kinetic energy (KE) parameters in three dimensions. Myocardial infarction (MI) is known to cause acute alterations in intra-cardiac blood flow but assessments of longitudinal changes are lacking.

Purpose. Assess longitudinal changes in LV flow post ST-elevation myocardial infarction (STEMI).

Method. Twenty acutely reperfused STEMI patients (13 men, 7 women, mean age 54 ± 9 years) underwent 3T CMR acutely (within 5-7 days) and 3 months post-MI.  CMR protocol included functional imaging, late gadolinium enhancement and 4D flow. Using Q-MASS, LV KE parameters were derived and indexed to LV end-diastolic volume (LVKEiEDV). Based on acute ejection fraction (EF), patients were grouped as follows: preserved (pEF) EF &gt;50%, reduced (rEF) EF &lt;50% including mild (rEF= 40-49%), moderate to severe (EF &lt;40%) impairment. 

Results. Out of 20 patients, 13 had rEF acutely (7 mild rEF, 6 moderate to severe rEF). Acute LVKEiEDV parameters varied significantly between pEF and rEF (Table). At 3 months, pEF and mild rEF patients showed a significant (P &lt; 0.05) reduction in average, systolic and peak-A wave LVKEiEDV. Mild rEF patients also had significant (P &lt; 0.05) reduction in minimal and peak-E wave LVKEiEDV. However in patients with moderate to severe rEF in the acute scan, there were no significant change by 3 months (Figure).

Conclusion. Following MI, 4D flow LVKE derived biomarkers significantly decreased over time in pEF and mild rEF groups but not in moderate to severe rEF group. 4D flow assessment might provide incremental prognostic value beyond EF assessment alone.

Table pEF (n = 7) rEF (n = 13) V1 V2 P-value V1 V2 P-value EF(%) 56 ± 5 55 ± 4 0.40 41 ± 7 47 ± 9 0.01 Infarct Size(%) 31 ± 20 15 ± 9 0.04 18 ± 13† 16 ± 11 0.41 LV KEiEDV parameters Average(µJ/ml) 9 ± 2 7 ± 2 0.02 10 ± 3† 8 ± 3 0.01 Minimal(µJ/ml) 1 ± 0.6 1 ± 0.5 0.46 1.3 ± 0.5 1 ± 0.6 0.03 Systolic(µJ/ml) 10 ± 4 7 ± 2 &lt;0.01 12 ± 4† 7 ± 3 &lt;0.01 Diastolic(µJ/ml) 8 ± 3 7 ± 2 0.13 9 ± 3 8 ± 3 0.09 Peak-E wave(µJ/ml) 22 ± 9 23 ± 8 0.44 20 ± 7 18 ± 10 0.23 Peak-A wave(µJ/ml) 18 ± 10 11 ± 4 0.04 17 ± 9 14 ± 7 0.02 †P &lt; 0.05 V1 comparison between pEF and rEF Abstract Figure

The effect of microvascular obstruction on the myocardial microstructure: a diffusion tensor imaging study

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): Heart Research UK

Background

Diffusion tensor cardiac magnetic resonance (DT-CMR) imaging allows for characterising myocardial microstructure in-vivo using mean diffusivity (MD), fractional anisotropy (FA), secondary eigenvector angle (E2A) and helix angle (HA) maps. Following myocardial infarction (MI), alterations in MD, FA and HA proportions have previously been reported. E2A depicts the contractile state of myocardial sheetlets, however the behaviour of E2A in infarct segments, and all DTI markers in areas of microvascular obstruction (MVO) is also not fully understood. 

Purpose

We performed spin echo DTI in patients following ST-elevation MI (STEMI) in order to investigate acute changes in DTI parameters in remote and infarct segments both with and without MVO.

Method

Twenty STEMI patients (16 men, 4 women, mean age 59) had acute (5 ± 2d) 3T CMR scans. CMR protocol included: second order motion compensated (M012) free-breathing spin echo DTI (3 slices, 18 diffusion directions at b-values 100s/mm2[3], 200s/mm2[3] and 500s/mm2[12], reconstructed resolution was 1.66x1.66x8mm); cine and late gadolinium enhancement (LGE) imaging. Average MD, FA, E2A HA parameters were calculated on a  16 AHA segmental level. HA maps were described by dividing values into left-handed HA (LHM, -90° &lt; HA &lt; -30°), circumferential HA (CM, -30° &lt; HA &lt; 30°), and right-handed HA (RHM, 30° &lt; HA &lt; 90°) and reported as relative proportions. Segments were defined as infarct (positive for LGE) and remote (opposite to the infarct). 

Results

DTI acquisition was successful in all patients (acquisition time 13 ± 5mins). Ten patients had evidence of MVO on LGE images. MD was significantly higher in infarct regions in comparison to remote; MVO-ve infarct segments had significantly higher MD than MVO + ve infarct segments (MD remote= 1.46 ± 0.12x10-3mm2/s, MD MVO + ve = 1.59 ± 0.12x10-3mm2/s, MD MVO-ve  = 1.75 ± 0.12x10-3mm2/s, ANOVA p &lt; 0.01). FA was reduced in infarct segments in comparison to remote; MVO-ve infarct segments had significantly lower FA than MVO + ve infarct segments (FAremote= 0.37 ± 0.02, FA MVO + ve = 0.31 ± 0.02 x 10-3mm2/s, MD MVO-ve =0.25 ± 0.02, ANOVA p &lt; 0.01).

E2A values were significantly lower in infarct segments compared to remote; MVO + ve infarct segments had significantly lower values than MVO-ve. (E2A remote= 57.4 ± 5.2°, E2A MVO-ve = 46.8 ± 2.5°, E2A MVO + ve = 36.8 ± 3.1°, ANOVA p &lt; 0.001). RHM% (corresponding to subendocardium) was significantly lower in infarct segments compared to remote; MVO + ve infarct segments had significantly lower RHM% than MVO-ve. (RHM remote= 37 ± 3%, RHM RHM MVO-ve= 28 ± 7%, MVO + ve= 8 ± 5%, ANOVA p &lt; 0.001).

Conclusion

The presence of MVO results in a decrease in MD and increase in FA in comparison to surrounding infarct segments. However, the reduction in E2A and right-handed myocytes on HA in infarct segments is further exacerbated by the presence of MVO. Further study is required to investigate the underlying mechanisms for such alterations in signal intensity.

Abstract Figure. A case of transmural septal MI with MVO

Diagnostic accuracy of 4D flow MRI comparing 2mm3 and 3mm3 spatial resolution

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): National Institute for Health Research, UK University of Leeds

Background

Cardiac magnetic resonance (CMR) examinations requiring repeated breath-holds are challenging in younger patients. While 4-dimensional phase-contrast (4D flow) CMR does not require breath-holds, acquisition has been lengthy. Therefore to date spatial resolution has been influenced mainly by scan length. With accelerated sequences becoming available, higher spatial resolution is becoming clinically feasible.

Purpose

We therefore evaluated the minimum spatial resolution in 4D flow CMR necessary for accurate clinical assessment.

Methods

Ten healthy volunteers (mean age 24.8 years) underwent cardiac examinations on a 3T scanner using a 4D Flow prototype sequence at 2x2x2mm3 (4DFlow2) and 3x3x3mm3 (4DFlow3) spatial resolution. Net forward flow (FF) and peak velocity (PV) using valve tracking were calculated with commercially available software and kinetic energy (KE) in the left ventricle (LV) was analysed using a research tool. Bland-Altman analysis was used for statistical assessment and is reported as bias ± limits of agreement.

Results

Aortic valve flow metrics were similar in 4DFlow2 (FF 94ml; PV 133cm/s) and 4DFlow3 (FF 95ml; PV 130cm/s), and both showed good agreement with 2D PC MRI (FF 93ml, Bland-Altman:1.6 ± 9.7 and 2.2 ± 13.5, respectively). Similar results were obtained for pulmonary valve flow (FF 138cm/s; Bland-Altman:4.7 ± 15.1 and 8.1 ± 18.2, respectively). Branch pulmonary artery (PA) FF showed good agreement with the main PA FF in 2D and 4DFlow2 (Bland-Altman:1.1 ± 15.9 and 1.1 ± 10.6, respectively), but not in 4DFlow3 (Bland-Altman:1.1 ± 32.5). Global LV KE measured by 4DFlow3 was on average 12% lower compared to 4DFlow2, whereas maximum systolic LV KE was similar in both acquisition methods.

Conclusions

3mm3 spatial resolution appears to be sufficient for clinical evaluation of aortic and pulmonary valves. Smaller vessels such as branch pulmonary arteries require higher resolution for accurate assessment. While no gold standard is available for kinetic energy assessment, our results suggest that some parameters LV energetic assessment is spatial resolution sensitive. Differences in SNR might also contribute to the differing results.

Abstract Figure. Bland-Altman plots for 4D flow MRI

Highly integrated workflows for exploring cardiovascular conditions: Exemplars of precision medicine in Alzheimer's disease and aortic dissection

For precision medicine to be implemented through the lens of in silico technology, it is imperative that biophysical research workflows offer insight into treatments that are specific to a particular illness and to a particular subject. The boundaries of precision medicine can be extended using multiscale, biophysics-centred workflows that consider the fundamental underpinnings of the constituents of cells and tissues and their dynamic environments. Utilising numerical techniques that can capture the broad spectrum of biological flows within complex, deformable and permeable organs and tissues is of paramount importance when considering the core prerequisites of any state-of-the-art precision medicine pipeline. In this work, a succinct breakdown of two precision medicine pipelines developed within two Virtual Physiological Human (VPH) projects are given. The first workflow is targeted on the trajectory of Alzheimer's Disease, and caters for novel hypothesis testing through a multicompartmental poroelastic model which is integrated with a high throughput imaging workflow and subject-specific blood flow variability model. The second workflow gives rise to the patient specific exploration of Aortic Dissections via a multi-scale and compliant model, harnessing imaging, computational fluid-dynamics (CFD) and dynamic boundary conditions. Results relating to the first workflow include some core outputs of the multiporoelastic modelling framework, and the representation of peri-arterial swelling and peri-venous drainage solution fields. The latter solution fields were statistically analysed for a cohort of thirty-five subjects (stratified with respect to disease status, gender and activity level). The second workflow allowed for a better understanding of complex aortic dissection cases utilising both a rigid-wall model informed by minimal and clinically common datasets as well as a moving-wall model informed by rich datasets.

6030Effects of adjunctive treatment with low-dose alteplase during primary percutaneous coronary intervention according to ischaemic time

Background

Microvascular obstruction affects half of patients with acute ST-segment elevation myocardial infarction and confers an adverse prognosis.

Purpose

We aimed to determine whether the efficacy and safety of a therapeutic strategy involving low-dose intra-coronary alteplase infused early after coronary reperfusion associates with ischaemic time.

Methods

We conducted a prospective, multicentre, parallel group, 1:1:1 randomised, dose-ranging trial in patients undergoing primary percutaneous coronary intervention. Ischaemic time, defined as the time from symptom onset to coronary reperfusion, was a pre-specified sub-group of interest. Between March 17, 2016, and December 21, 2017, 440 patients presenting at 11 hospitals in the UK were enrolled with follow up to 3 months. Patients with acute myocardial infarction due to occlusion of a major coronary artery presenting ≤6 hours from symptom onset were randomly assigned to treatment with placebo, alteplase 10mg or alteplase 20mg. The primary outcome was the amount of microvascular obstruction disclosed by cardiac magnetic resonance imaging at 2–7 days. Secondary outcomes included infarct size, myocardial haemorrhage, left ventricular ejection fraction, and troponin T area-under-the curve.

Results

440 patients were randomized (figure), the primary endpoint was achieved in 396 (90%), seventeen (3.9%) withdrew and all other patients were followed up to 3 months. In the primary analysis, the amount of microvascular obstruction did not differ between the groups. Their ischaemic times were: ≤2 hours, n=98; ≥2–<4 hours, n=215; and ≥4–6 hours, n=83.

In patients with an ischaemic time ≥4 hours, treatment with alteplase (10 mg, n=26; 20 mg, n=30) was associated with a dose dependent increase in the amount (mean) of microvascular obstruction (% left ventricular mass) compared to placebo (n=27) 1.14 vs. 3.11 vs. 5.20; mean difference on square root scale 0.81 (95% CI 0.21, 1.42), p=0.009. The interaction test between ischaemic time and treatment (active vs. placebo) was not statistically significant p=0.06, however when the interaction was assessed for a trend across treatment groups this did reach statistical significance, p=0.018.

Furthermore, a higher proportion of patients presenting ≥4–6 hours treated with 20 mg of alteplase had myocardial haemorrhage (59.3%) compared to the placebo group (28.0%), odds ratio 3.81 (95% CI 1.19, 12.25), p=0.025. The amount of haemorrhage was also greater; estimated mean difference 3.49 (95% CI 1.22, 5.75), p=0.0026. No between-treatment group differences for myocardial haemorrhage were observed in patients presenting with shorter ischaemic times.

Study flow diagram

Conclusions

In patients presenting with an ischaemic time ≥4 hours, adjunctive treatment with low-dose intra-coronary alteplase during primary PCI was associated with increases in microvascular obstruction and myocardial haemorrhage. The mechanism may involve haemorrhagic transformation within the infarct core.

Acknowledgement/Funding

NIHR EME programme (reference: 12/170/45); British Heart Foundation (BHF reference FS/16/74/32573)

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

The chlorine isotope fingerprint of the lunar magma ocean

The Moon contains chlorine that is isotopically unlike that of any other body yet studied in the Solar System, an observation that has been interpreted to support traditional models of the formation of a nominally hydrogen-free ("dry") Moon. We have analyzed abundances and isotopic compositions of Cl and H in lunar mare basalts, and find little evidence that anhydrous lava outgassing was important in generating chlorine isotope anomalies, because (37)Cl/(35)Cl ratios are not related to Cl abundance, H abundance, or D/H ratios in a manner consistent with the lava-outgassing hypothesis. Instead, (37)Cl/(35)Cl correlates positively with Cl abundance in apatite, as well as with whole-rock Th abundances and La/Lu ratios, suggesting that the high (37)Cl/(35)Cl in lunar basalts is inherited from urKREEP, the last dregs of the lunar magma ocean. These new data suggest that the high chlorine isotope ratios of lunar basalts result not from the degassing of their lavas but from degassing of the lunar magma ocean early in the Moon's history. Chlorine isotope variability is therefore an indicator of planetary magma ocean degassing, an important stage in the formation of terrestrial planets.