Cardiac pressure overload exposes hidden anthracycline-induced cardiotoxicity: results from a preclinical large-animal trial

Aim

The purpose of this work is to elucidate if low cumulative doxorubicin doses has a differential cardiac impact in pigs with or without pre-existing LV pressure overload. Impact of interventions on LV anatomy, function and tissue composition was evaluated by serial cardiac magnetic resonance (CMR). At the end of the in vivo protocol, hearts were processed to evaluate differential molecular pathways in both groups.

Methods

A total of 95 pigs were included. 52 animals underwent supravalvular aortic banding to generate LV hypertrophy, while another did not. 4 months after banding (a time where LV hypertrophy is prominent), animals in both groups were randomized to receive intravenous doxorubicin (1 mg/kg once per week, for 5 weeks) or saline. Thus, 4 study groups (N=15–22 per group) comprised the study population (banding yes/no, doxorubicin yes/no). All individuals underwent to serial Cardiac Magnetic Resonance exams every month and were sacrificed fo ex vivo analysisat 4 months after doxorubicin injections. To discriminate between doxorubicin effect in banding/no banding groups but also the effect of banding in doxorubicin protocols, t-test was used for two-group comparisons after two-way ANOVA test. Differences were considered statistically significant at p<0.05. Logrank test was performed to compare survival curves.

Results

Pigs receiving doxorubicin after cardiac pressure overload showed an increased mortality compared with the other groups (p=0.006). Only this group developed a progressive cardiotoxicity phenotype, characterized as a significant decline in cardiac function compared with control operated animals (49.7% ± 8.1 vs 79.6% ± 6.7, p<0.001), but also with non-operated pigs receiving the same anthracycline regime (vs 63.9% ± 4, p<0.001). Cardiac deterioration was based mainly on systolic dysfunction compared with control operated animals (38.2 ml indexed ± 3.5 vs 13.6±6.6, p=0.01) and non-operated pigs treated with doxorubicin (vs 26.6 ml indexed ± 6.6, p<0.001). In-vivo CMR tissue characterization revealed elevation on T2 relaxation times compared with Control animals (46.2 ms ± 3.5 vs 41.8±2.7, p=0.04) with no Extracellular Volume expansion. Ex-vivo histological analyses showed presence of intra-cardiomyocyte vacuolization in the Banding + DOXO group (p=0.01). Regarding mitochondrial phenotype, animals with Banding + DOXO exhibited a fragmented phenotype with extremely damaged mitochondria. Animals with only aortic banding exhibit increasing cardiac hyperkinesia and cardiac hypertrophy at the end of the study.

Conclusion(s)

We demonstrated that a very low dosage of doxorubicin is enough to exert cardiotoxicity in a pressure overload scenario. Characterized as a deterioration in cardiac function, myocardial edema, classical histological lesions and mitochondrial damage. Providing preclinical evidence that modest anthracycline protocols may be harmful for patients with cardiac comorbidities.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): ERC MATRIX

Cardiac magnetic resonance imaging derived reference values for ventricular anatomy and function and myocardial tissue characterization in adolescents: the EnIGMA study

Introduction

Cardiac magnetic resonance (CMR) imaging is a precise tool for the assessment of cardiac anatomy and function. However, studies providing reference values for CMR parameters, including myocardial tissue properties, in healthy adolescents are scarce.

Purpose

To provide CMR derived reference values for biventricular mass, volumes and function measured by cine steady-state free-precession (SSFP) sequences and myocardial tissue relaxation properties as measured by native T1- and T2-mapping sequences in healthy adolescents.

Methods

A comprehensive non-contrast CMR study was performed in healthy adolescents aged 15 to 18 years enrolled in the “Early ImaginG Markers of unhealthy lifestyles in Adolescents” (EnIGMA) project using a 3-Tesla CMR scanner between March 2021 and October 2021. The imaging protocol included a cine SSFP to provide high-quality images for chamber size and function analysis, and a T2-GraSE mapping and native T1-mapping sequences (MOLLI Scheme 5 (3) 3) to provide precise myocardial relaxation time properties. Images were analyzed by experienced observers using the Cardiac Analysis tool available at IntelliSpace Portal following a standard protocol. In cine SSFP sequences, right and left ventricles were manually contoured for end-diastolic and end-systolic phases in the short-axis orientation, respectively (Figure 1A, B). Native T1 and T2 maps were analyzed in a mid-ventricular short axis slice and summarized values per individual were determined (Figure 1C, D). Student's t-tests were used for between-gender comparisons.

Results

CMR scans were performed in 123 adolescents (63 girls, 51.2%) with a mean age of 16.0 years (standard deviation (SD)=0.5), mean body mass index of 21.4 (SD=3.2) kg/m2, mean body surface area of 1.69 (SD=0.16) m2, and mean heart rate during CMR acquisitions of 69 (SD=11) beats/minute. Reference percentiles (P) 3, 10, 25, 50, 75, 90 and 97 for the different parameters analyzed by gender are provided in Figure 2. Mean left and right ventricular end-diastolic indexed volumes were higher in boys than in girls (91.5 vs 78.1 ml/m2, p<0.01; and 101.1 vs 84.2 ml/m2, p<0.01), as well as the indexed cardiac mass (48.4 vs 36.4 g/m2, p<0.01). Left ventricular ejection fraction (LVEF) was similar in boys and girls (62.0 vs. 62.9%, p=0.23), whereas right ventricular ejection fraction was slightly lower in boys than in girls (55.3 vs. 57.1%, p=0.03). Mean myocardial native T1 relaxation time was 1253 (SD=28) ms in girls and 1215 (SD=23) ms in boys (p<0.01), whereas mean myocardial T2 relaxation time was 44.1 (SD=2.3) ms and 44.4 (SD=2.0) ms in girls and boys, respectively (p=0.46).

Conclusion

This study provided CMR derived reference values for biventricular anatomy, function, and myocardial tissue properties, in healthy adolescents aged 15 to 18 years. This information may be useful for the differential diagnosis of cardiac diseases, such as cardiomyopathies and myocarditis, in adolescent population.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): Instituto de Salud Carlos III (ISCIII)-Fondo de Investigaciόn SanitariaEuropean Regional Development Fund/European Social Fund (“A way to make Europe”/“Investing in your future”)

Non-contrast cardiac magnetic resonance imaging after SARS-CoV2 infection or vaccination in asymptomatic adolescents: insights from the EnIGMA study

Background

Myocarditis after SARS-CoV2 infection or vaccination is rare, but seems to be relatively more frequent in young population. Cardiac magnetic resonance (CMR) T2 weighted sequences have the potential to detect subclinical myocarditis. However, there is paucity of data on the potential myocardial involvement after SARS-CoV2 infection or vaccination in asymptomatic adolescents.

Purpose

To evaluate the presence of subclinical myocardial damage in adolescents who were infected with SARS-CoV2 or vaccinated against SARS-CoV2 using non-contrast CMR imaging.

Methods

Asymptomatic adolescents enrolled in the “Early ImaginG Markers of unhealthy lifestyles in Adolescents” (EnIGMA) project were scanned using a 3-Tesla CMR scanner between March 2021 and October 2021. CMR scans included CINE imaging and myocardial T2-mapping sequences. SARS-CoV2 IgG antibody testing was performed in capillary blood samples, and date of confirmed SARS-CoV2 infection and/or vaccination if any was collected. Participants were assigned to three different groups according to SARS-CoV2 status: Group 1 (non-infected and non-vaccinated), Group 2 (infected and non-vaccinated), and Group 3 (vaccinated, independently of past infection status). CMR images were analyzed by experienced observers blinded to adolescent's SARS-CoV2 status. ANOVA and multiple regression analysis, together with correlation coefficients, were used to study between-group differences and associations among variables of interest.

Results

A total of 115 adolescents with a mean age of 16.0 years (standard deviation (SD)=0.4), 54% girls, completed the CMR study and SARS-CoV2 data successfully, and were assigned to Group 1 (n=72), Group 2 (n=22), and Group 3 (n=21). Left and right ventricular ejection fraction (LVEF/RVEF) did not significantly differ among groups: mean LVEF was 62.8% (SD=4.1), 63.0% (SD=3.7) and 60.9% (SD=3.9) [p=0.12] and mean RVEF was 56.5% (SD=4.2), 56.5% (SD=5.5) and 54.5% (SD=5.1) [p=0.23] in Groups 1, 2 and 3, respectively. Similarly, there were no between-group significant differences in myocardial T2 relaxation values: mean T2 values were 44.1 ms (SD=2.2), 44.1 ms (SD=1.8) and 44.4 ms (SD=1.9) in Groups 1, 2, and 3, respectively (p=0.63) (Figure 1). No differences were found either after adjusting for age and gender. Median time (interquartile range) from date of infection or vaccination to CMR acquisition was 133 (121) days and 28 (38) days in Group 2 and Group 3, respectively. No correlation between time from infection/vaccination to CMR acquisition and T2 values was detected (Figure 2).

Conclusions

This observational study did not find evidence of subclinical myocardial involvement after SARS-CoV2 infection or vaccination in asymptomatic adolescents, as assessed with T2-mapping magnetic resonance imaging.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Instituto de Salud Carlos III (ISCIII)-Fondo de Investigaciόn Sanitaria.European Regional Development Fund/European Social Fund (“A way to make Europe”/“Investing in your future”.

Remote ischemic preconditioning ameliorates anthracycline-induced cardiotoxicity and preserves mitochondrial integrity: results from a randomized preclinical trial in pigs

Introduction

Anthracycline-induced cardiotoxicity (AIC) is a serious adverse effect occurring in a significant proportion of patients. Irreversible mitochondrial damage is a central mechanism of AIC. Despite many efforts, there is a lack of therapies able to prevent AIC. Remote ischemic preconditioning (RIPC) could be a promising therapy to prevent AIC due to the scheduled application of chemotherapy in cancer patients.

Purpose

To evaluate the cardioprotective efficacy of RIPC in large animal model of AIC.

Methods

Large-White pigs (n=20) underwent a validated protocol of AIC consisting on five intracoronary doxorubicin injections (0.45 mg/kg), on weeks 0, 2, 4, 6, 8 of the study. Pigs were randomized before the initiation of the study to remote ischemic pre-conditioning (RIPC, 3 cycles of 5 min lower limb ischemia followed by 5 min reperfusion) or sham procedure immediately before doxorubicin injections. An additional group of 10 pigs without any exposure to doxorubicin was carried out as controls. Pigs underwent a comprehensive serial cardiac magnetic resonance (CMR) exam baseline, and on weeks 6, 8, 12, and 16. After 16-week CMR, pigs were sacrificed and tissue samples collected. A second group of 10 pigs (randomized 1:1 for RIPC) underwent the same protocol but were sacrificed 2 weeks after the third doxorubicin dose for early evaluation of tissue changes. Primary endpoint of the study was CMR-based left ventricular ejection fraction on week 16.

Results

Until week 6 (time of fourth doxorubicin injection), LVEF remained unchanged in both groups. From there on, a progressive decline in LVEF was observed. LVEF depression trajectory was blunted in RIPC animals. Compared to controls, pigs undergoing RIPC before each doxorubicin dose had a significantly higher LVEF at week 16: median (IQR) 45% (27–50%) vs 33% (19–47%) in RIPC and controls respectively, p=0.04. Improvement in LVEF was mainly due to a more preserved contractile function, as evidence by smaller LVESV, and better regional contractile function. After 3 doxorubicin doses, a time where global (LVEF) and regional contractile function was still unchanged, transmission electron microscopy (TEM) showed fragmented mitochondria with remodeled cristae only in control pigs. At the end of the 16 weeks, TEM evaluation in control pigs (as compared to RIPC pigs) showed overt cardiomyocyte's mitochondrial fragmentation with overt structural derangement. At this time, RIPC pigs had significantly less interstitial fibrosis on histology.

Conclusions

In a translatable large animal model of AIC, RIPC applied immediately before each doxorubicin cycle resulted in a preservation of cardiac contractility with significantly higher long-term LVEF and less cardiac fibrosis. RIPC prevented the deleterious effects of doxorubicin on mitochondria since early stages of AIC. RIPC is a promising intervention to be tested in clinical trials to prevent cardiotoxicity.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): The CNIC is supported by the Instituto de Salud Carlos III (ISCIII), the Ministerio de Ciencia e Innovaciόn and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence (SEV-2015-0505)

New three-dimensional volumetric ultrasound probe for accurate quantification of atherosclerotic plaque volume

Background

Atherosclerosis burden is directly related with the development of clinical cardiovascular events. Recent ESC guidelines endorse carotid and/or femoral plaque burden assessment as a complement for conventional cardiovascular risk evaluation. Compared with previous 3D probes, new 3D-matrix transducers for vascular ultrasound imaging are designed to improve functionality and image quality for an accurate study of atherosclerosis burden.

Purpose

We aimed to validate a commercially available 3D-matrix transducer for plaque volume measurement in early disease stages (small plaques) when accurate plaque detection and quantification is challenging, and intermediate-advanced (medium-large size) plaques in carotid and femoral arteries.

Methods

We performed an ex vivo study using carotid and femoral arterial specimens from a pig model of early atherosclerosis in which actual 3D vascular ultrasound (3DVUS) volume measurements obtained using the new 3D-matrix transducer (XL14–3) were correlated against gold-standard histological measurements. Moreover, we performed a clinical experiment in a subset of intermediate-high risk patients from the “Athero-Brain: Head to Heart (H2H)” study with patent carotid and femoral atherosclerosis for comparing plaque volume evaluated by the new XL14–3 3D-matrix transducer, based on “electronic” 3D-sweep technology, with that measured by previously validated VL13–5 “mechanical” 3D-sweep transducer that uses a mechanically steered linear-array.

Results

In the ex vivo setting, we evaluated 11 atherosclerotic plaques (6 carotid and 5 femoral plaques, mean plaque volume 16.5±22.5 mm3 ranging in size from 1 to 56 mm3), finding a strong correlation between 3DVUS measures and the histological gold-standard with an intraclass correlation coefficient (ICC) of 0.994 (95% CI [0.976; 0.998]). In the clinical setting, we measured 25 plaques (14 carotid and 11 femoral plaques; mean plaque volume 273.4±216.5 mm3 ranging in size from 10 to 859 mm3) from 8 patients (mean age 75±5 years old, 45% men) finding again a strong correlation between 3DVUS electronic-based and mechanical-based volume measurements (ICC=0.996 95% CI [0.991; 0.998]). Correlation and Bland-Altman plots for the measurements of both experiments are displayed in the figure and showed good agreement (Slope close to 1 in the Passing Bablock analysis) with small or lower than clinically relevant differences between measurements.

Conclusions

3DVUS using new matrix technology accurately measures plaque volumes of early (small-size) to intermediate-advanced plaques located in superficial arteries like carotid and femoral arteries.

Figure 1

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): National Institute of Health Carlos III Institute through an Integrated Excellence Project Grant

Beneficial effect of colchicine in an animal model of atherosclerosis

Background

Atherosclerosis is a chronic inflammatory disease and colchicine demonstrated clinical benefits in the treatment of stable coronary artery disease.

Purpose

Our aim was to assess the anti-inflammatory effects of colchicine on atherosclerotic vascular disease.

Methods

Atherosclerosis was induced in the abdominal aorta of 20 rabbits with high-cholesterol diet and balloon endothelial denudation. The study protocol lasted 36 weeks. After 18 weeks rabbits were randomized to receive either colchicine or placebo. Two animals died in each group. At randomization and at the end of the study, all animals underwent MRI and positron 18F-FDG PET/CT. In this post-hoc subgroup analyses, animals of each group in the first quartile of cholesterol levels were excluded. For MRI plaque volume values were expressed as Normalized Wall Index (NWI) and for 18F-FDG PET/CT values were expressed as mean maximum standard uptake (meanSUVmax). Statistical comparisons were made by using the Mann-Whitney U test for unpaired data and Wilcoxon signed-rank test for paired data.

Results

Results are summarized in Table 1. Animals with higher levels of cholesterol (6 per group) showed significant differences in favor to colchicine group, both as NWI at the end of the protocol 0.47 (IQR 0.05) in the colchicine group versus 0.52 (IQR 0.03) in the placebo; p=0.01] and as relative increase in meanSUVmax [−4.0% (IQR 30.1) in the colchicine group versus 35.1 (IQR 59.0) in the placebo; p 0.041] (Figure 1).

Conclusions

Colchicine may stabilize atherosclerotic plaque by reducing inflammatory activity and plaque burden.

Figure 1

Funding Acknowledgement

Type of funding source: Public grant(s) – EU funding. Main funding source(s): This work was supported by a grant from the Sociedad Española de Cardiología and a grant from the Carlos III Institute of Health of Spain and Fondo Europeo de Desarrollo Regional (FEDER, “Una manera de hacer Europa”)

Small bowel obstruction caused by pericaecal hernia resolved with a laparoscopic approach

Small bowel obstruction from internal hernias is a familiar pathology for the surgeon, with an incidence of 0.5-5.8%. However, pericaecal hernia is a very uncommon type of internal hernia. Diagnosis and early treatment are essential to avoid strangulation and necrosis of the incarcerated small bowel. We report a case of an 84-year-old woman with no previous history of abdominal surgery who came to our hospital having endured 6 hours of abdominal pain and vomiting. Following physical examination and computed tomography, a diagnosis of small bowel obstruction caused by pericaecal hernia was made and emergency surgery was performed. The hernia was successfully reduced with a laparoscopic approach. Although pericaecal hernia is a rare disease, surgeons should bear it in mind as a differential diagnosis in small bowel obstruction.

P3108Microcirculation injury is involved in anthracycline-induced cardiac toxicity

Background/Introduction

Cardiotoxicity (CT) is a major concern for cancer patients receiving anthracyclines. While the effect of anthracyclines on cardiomyocytes is well established, its impact on myocardial microcirculation has not been characterized.

Purpose

To evaluate the effect of low and high cumulative doses of doxorubicin (doxo) on anatomical and functional vasculature status evaluated by serial invasive Coronary Flow Reserve (CFR) and Cardiac Magnetic Resonance (CMR)-based quantitative perfusion in a large animal model.

Methods

Large-white male pigs (n=15, 30 kg) were distributed in 2 doxo regimes: Group 1) high cumulative dose (5 biweekly intracoronary (i.c) injections of 0.45 mg/kg of doxo) followed-up until week 16 (a time when severe left ventricular systolic dysfunction is present) and then sacrificed (N=5); Group 2) low cumulative dose of doxo (3 biweekly i.c. doses) followed-up until week 16 and then sacrificed (N=5)). Group 3) pigs sacrificed at 6 weeks (2 weeks after third doxo dose), N=5. Invasive catheter-based CFR was evaluated after i.c papaverine (0.5 mg/kg) while CMR quantitative rest perfusion maps were obtained after intravenous injection of gadolinium. CFR and CMR were performed before doxo, and at 0, 2, 4, 6 and 16 weeks thereafter. Cardiac vessels were evaluated ex vivo with trichrome staining. Statistical analysis was performed using one-way ANOVA with multiple pairwise comparisons (vs. baseline) and Bonferroni corrected p-value.

Results

CFR and CMR-quantitative myocardial perfusion were non-significantly reduced after 3 doxo doses despite myocardial vasculature was overtly injured on histology at this timepoint. Animals receiving 5 doxo doses suffered a progressive deterioration of CFR and CMR-perfusion until week 16 (1.41±0.23 vs 3.71±0.94 at baseline [p=0.014] and 65.4±18.2 ml/100g/min vs 154.9±56.3 ml/100g/min at baseline [p=0.046], respectively). At 16 weeks histology revealed extensive microvascular damage with media layer involvement and perivascular fibrosis. Pigs receiving 3 doxo doses showed less pronounced CFR reduction on long-term follow-up (3.13±0.82 vs 3.69±1.57 at baseline [p>0.05] but overt CMR-perfusion reduction (138.3±11.9 vs 197.8±37.1 at baseline [p=0.045]). On histology, damage of vasculature including arterioles was evidenced to a lesser extent than in the high cumulative doxo dose group with mild microvascular disruption and smooth muscle vacuolization.

Conclusions

Doxorubicin results in a progressive damage of the myocardial microcirculation. Even low cumulative doxo doses (resulting in no overt left ventricular dysfunction) results in vascular damage. The microcirculation status may serve as an early marker of doxorubicin cardiotoxicity.

Thrombosis of the abdominal aorta secondary to Brucella spondylitis

Spondylitis is one of the most frequent osteoarticular complications of Brucella infection in adults. Occasionally it gives rise to soft tissue paravertebral or epidural masses, which can compress surrounding structures. A patient with thrombosis of the abdominal aortic artery secondary to Brucella lumbar spondylitis is presented here, a complication that has not been previously reported.