Genetic Architecture of Acute Myocarditis and the Overlap With Inherited Cardiomyopathy

BACKGROUND

Acute myocarditis is an inflammatory condition that may herald the onset of dilated cardiomyopathy (DCM) or arrhythmogenic cardiomyopathy (ACM). We investigated the frequency and clinical consequences of DCM and ACM genetic variants in a population-based cohort of patients with acute myocarditis.

METHODS

This was a population-based cohort of 336 consecutive patients with acute myocarditis enrolled in London and Maastricht. All participants underwent targeted DNA sequencing for well-characterized cardiomyopathy-associated genes with comparison to healthy controls (n=1053) sequenced on the same platform. Case ascertainment in England was assessed against national hospital admission data. The primary outcome was all-cause mortality.

RESULTS

Variants that would be considered pathogenic if found in a patient with DCM or ACM were identified in 8% of myocarditis cases compared with <1% of healthy controls (P=0.0097). In the London cohort (n=230; median age, 33 years; 84% men), patients were representative of national myocarditis admissions (median age, 32 years; 71% men; 66% case ascertainment), and there was enrichment of rare truncating variants (tv) in ACM-associated genes (3.1% of cases versus 0.4% of controls; odds ratio, 8.2; P=0.001). This was driven predominantly by DSP-tv in patients with normal LV ejection fraction and ventricular arrhythmia. In Maastricht (n=106; median age, 54 years; 61% men), there was enrichment of rare truncating variants in DCM-associated genes, particularly TTN-tv, found in 7% (all with left ventricular ejection fraction <50%) compared with 1% in controls (odds ratio, 3.6; P=0.0116). Across both cohorts over a median of 5.0 years (interquartile range, 3.9-7.8 years), all-cause mortality was 5.4%. Two-thirds of deaths were cardiovascular, attributable to worsening heart failure (92%) or sudden cardiac death (8%). The 5-year mortality risk was 3.3% in genotype-negative patients versus 11.1% for genotype-positive patients (Padjusted=0.08).

CONCLUSIONS

We identified DCM- or ACM-associated genetic variants in 8% of patients with acute myocarditis. This was dominated by the identification of DSP-tv in those with normal left ventricular ejection fraction and TTN-tv in those with reduced left ventricular ejection fraction. Despite differences between cohorts, these variants have clinical implications for treatment, risk stratification, and family screening. Genetic counseling and testing should be considered in patients with acute myocarditis to help reassure the majority while improving the management of those with an underlying genetic variant.

Normal values for paediatric atrial volumes assessed by steady-state free-precession cardiovascular magnetic resonance

Background

Measurement of atrial volumes by steady-state free precession (SSFP)cardiovascular magnetic resonance (CMR) is becoming increasingly important in the treatment and follow-up of paediatric congenital heart disease. It has prognostic value in terms of heart failure and cardiovascular death. However, CMR normal values for the clinically often used mono- and biplane area-length method in children are lacking.

Aims

We sought to create paediatric normal values for atrial volumes using the mono- and biplane area-length method.

Methods

In a retrospective study design, CMR data sets of 157 healthy children with an age range between 4 and 18 years from two centers in the UK and Germany were evaluated. In a four-chamber (4ch-) view, left and right atrial (LA, RA) endocardial borders were segmented during end-diastole and end-systole to calculate minimal and maximal atrial volumes (LAmin, LAmax, RAmin, RAmax) using the monoplane area-length method. Additionally, end-diastolic and end-systolic LA endocardial borders were segmented in a two-chamber (2ch-) view. Using the measurements from the 2ch- and 4ch-views, minimal and maximal LA volumes were calculated using the biplane area-length method. Atrial volumes were normalized for body surface area (BSA in m2). Sex-specific reference curves were created using the lambda mu sigma method.

Results

The median age was 13.8±2.81 years (53 girls).

In children from 4–10 years average atrial volumes measured: monoplane 4ch: LAmin 10.2±3.5 ml/m2, LAmax 28.8±7.4 ml/m2, RAmin 14.1±6.3 ml/m2, RAmax 27.0±11.4 ml/m2; monoplane 2ch: LAmin 10.9±4.1 ml/m2, LAmax 27.0±6.1 ml/m2; biplane: LAmin 10.2±3.3 ml/m2, LAmax 27.4±5.7 ml/m2.

In children from 11–18 years average atrial volumes measured: monoplane 4ch: LAmin 13.6±4.9 ml/m2, LAmax 34.1±9.1 ml/m2, RAmin 19.2±6.8 ml/m2, RAmax 34.2±9.6 ml/m2; monoplane 2ch: LAmin 13.2±4.9 ml/m2, LAmax 31.4±9.7 ml/m2; biplane: LAmin 12.9±4.4 ml/m2, LAmax 31.8±8.8 ml/m2.

Separate centile charts and centile tables for boys and girls for all volumetric parameters were created.

Conclusion

We provide paediatric CMR reference values for atrial volumes. They can be used in the diagnosis and follow-up of congenital or acquired heart disease in children and for research purposes.

Funding Acknowledgement

Type of funding sources: None.

Normal values for paediatric biventricular volumes, ejection fraction and mass – influence of cardiovascular magnetic resonance analysis techniques

Background

Measurement of ventricular volumes and function by steady-state free precession (SSFP) cardiovascular magnetic resonance (CMR) is an important diagnostic tool in the treatment and follow-up of paediatric congenital heart disease. However, normal values are rare and the CMR analysis methods are inconsistent.

Aims

We sought to create two sets of ventricular normal values for different CMR analysis (contouring) methods.

Methods

In a retrospective study design, CMR data sets of 154 healthy children with an age range between 4 and 18 years from two centers in the UK and Germany were evaluated. Left and right ventricular end-diastolic and end-systolic volumes (LVEDV, LVESV, RVEDV, RVESV), ejection fraction (RVEF, LVEF) and myocardial mass (LVMM, RVMM) were analysed from short axis steady-state free precession images by using two different analysis techniques: 1) papillary muscles, myocardial trabeculations and the moderator band were included in the ventricular volume and excluded from the ventricular mass (Figure 1), 2) papillary muscles, myocardial trabeculations and the moderator band were excluded from the ventricular volume and included in the ventricular mass (Figure 2). Sex-specific reference curves were created separately for both ventricular contouring methods using the lambda mu sigma method. Correlations between variables were analyzed with the Spearman's rank correlation. Contouring methods were compared through Bland-Altman analysis.

Results

The mean age was 13.85±2.8 years (53 girls).

In children from 4 to 10 years average ventricular volumes and mass normalized for body surface area (BSA) measured:

In children from 11 to 18 years average ventricular volumes and mass measured:

Separate centile charts and centile tables for boys and girls for all cardiac parameters were created.

Conclusion

We provide paediatric CMR reference values for biventricular volumes, ejection and masses for two different CMR contouring methods. They can be used in the diagnosis and follow-up of congenital or acquired heart disease in children and for research purposes.

Funding Acknowledgement

Type of funding sources: None. Figure 1Figure 2

Cardiovascular magnetic resonance (CMR) normal values for pulmonary arteries in healthy children and adolescents

Funding Acknowledgements

Type of funding sources: None.

Background

Changes in the right ventricular outflow tract (RVOT) and pulmonary arteries (PAs) are often seen in paediatric patients with congenital heart disease (CHD), pulmonary hypertension or genetic disorders (e.g. Marfan syndrome, Loeys-Dietz syndrome, Williams syndrome, DiGeorge syndrome). Cardiovascular magnetic resonance (CMR) imaging is an excellent method to visualize the RVOT and PAs without the use of ionizing radiation and contrast media but for the interpretation of CMR data in the paediatric population the knowledge of normal values is crucial. However, normal values for pulmonary arteries from contrast-free cine CMR images are lacking.

Purpose

The aim of this retrospective multicentre study was to establish reference ranges for the diameters of the mean PA (MPA), right PA (RPA) and left PA (LPA).

Methods

163 CMR scans of healthy children and adolescents (mean age 13.8 ± 2.9 years; range 5-18 years) from two centres in the UK and Germany were included. The diameter of the MPA was measured in sagittal-oblique RVOT cine images and transaxial cine stacks, whereas the diameter of the RPA and LPA were measured from transaxial stacks and specific pulmonary artery branch cine images.

Results

Mean systolic and diastolic diameters for the MPA were 22.1 ± 2.8 mm (14.4 ± 2.2 mm/m²)/ 17.2 ± 2.3 mm (11.3 ± 1.9 mm/m²) measured in RVOT cine stacks. Mean systolic and diastolic diameters for the RPA and LPA were:  1) RPA, 12.4 ± 1.7 mm (7,9 ± 1,6 mm/m²)/ 9.8 ± 1.6 mm (5.9 ± 1.8 mm/m²) and 2) LPA, 13.3 ± 1.5 mm (8.3 ± 2.1 mm/m²)/ 10.8 ± 1.5 mm (6.8 ± 1.8 mm/m²). Separate centile charts for boys and girls for the MPA were created.

Conclusions

We established CMR normal values for the MPA, RPA and LPA for children and adolescents. Our data might be useful for the detection of PA stenosis and dilatation and may serve as a reference in future studies.

Diffusion tensor cardiovascular magnetic resonance detects altered myocardial microstructure in patients with acute st-elevation myocardial infarction

Background

Diffusion Tensor Cardiovascular Magnetic Resonance (DT-CMR) can quantify metrics of tissue integrity (mean diffusivity [MD] and fractional anisotropy [FA]) and changes in laminar microstructures (sheetlets), which reorientate from more wall-parallel in diastole (DIA) towards wall-perpendicular in systole (SYS) as the myocardium thickens, quantified by E2 angle [E2A]. Microstructural changes after STEMI may provide new insights into adverse LV remodelling and risk stratification.

Methods

In vivo DT-CMR was performed 3–5 days after PPCI for first presentation STEMI (N=19, mean age 57±9, 79% male). DT-CMR was acquired in 2 short-axes (SYS & DIA) using a STEAM-EPI sequence. 12 segment analysis of MD, FA, E2A and E2A mobility (ΔE2A = E2ASYS − E2ADIA) was performed. Infarct (INF) segments were defined as &gt;25% LGE, adjacent (ADJ, located contiguous to INF) and remote (REM, all other segments). Wilcoxon signed rank tests were used with threshold P&lt;0.017 (Bonferroni corrected).

Results

See Table.

MD in both SYS and DIA was significantly higher in INF and ADJ regions compared to REM. FA in both SYS and DIA was lower in the INF and ADJ compared to REM. E2ADIA was higher in INF, indicating a more wall-perpendicular orientation of sheetlets, compared to ADJ and REM zones. E2ASYS in INF was significantly reduced, indicating a more wall-parallel orientation of sheetlets, compared to ADJ and REM regions, resulting in significantly reduced sheetlet mobility (ΔE2A).

Conclusions

Microstructural changes can be detected after acute STEMI by in vivo DT-CMR. Zonal changes in MD and FA may suggest loss of barriers to water diffusion and altered cardiomyocyte organisation, respectively. We provide the first report of reduced sheetlet mobility after acute STEMI in INF. Ongoing work is evaluating the mechanisms and prognostic importance of altered sheetlet mobility after STEMI.

Funding Acknowledgement

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

Coronary artery bypass surgery with or without mitral valve annuloplasty in moderate functional ischemic mitral regurgitation: final results of the Randomized Ischemic Mitral Evaluation (RIME) trial

BACKGROUND

The role of mitral valve repair (MVR) during coronary artery bypass grafting (CABG) in patients with moderate ischemic mitral regurgitation (MR) is uncertain. We conducted a randomized, controlled trial to determine whether repairing the mitral valve during CABG may improve functional capacity and left ventricular reverse remodeling compared with CABG alone.

METHODS AND RESULTS

Seventy-three patients referred for CABG with moderate ischemic MR and an ejection fraction >30% were randomized to receive CABG plus MVR (34 patients) or CABG only (39 patients). The study was stopped early after review of interim data. At 1 year, there was a greater improvement in the primary end point of peak oxygen consumption in the CABG plus MVR group compared with the CABG group (3.3 mL/kg/min versus 0.8 mL/kg/min; P<0.001). There was also a greater improvement in the secondary end points in the CABG plus MVR group compared with the CABG group: left ventricular end-systolic volume index, MR volume, and plasma B-type natriuretic peptide reduction of 22.2 mL/m(2), 28.2 mL/beat, and 557.4 pg/mL, respectively versus 4.4 mL/m(2) (P=0.002), 9.2 mL/beat (P=0.001), and 394.7 pg/mL (P=0.003), respectively. Operation duration, blood transfusion, intubation duration, and hospital stay duration were greater in the CABG plus MVR group. Deaths at 30 days and 1 year were similar in both groups: 3% and 9%, respectively in the CABG plus MVR group, versus 3% (P=1.00) and 5% (P=0.66), respectively in the CABG group.

CONCLUSIONS

Adding mitral annuloplasty to CABG in patients with moderate ischemic MR may improve functional capacity, left ventricular reverse remodeling, MR severity, and B-type natriuretic peptide levels, compared with CABG alone. The impact of these benefits on longer term clinical outcomes remains to be defined.

Troponin release following endurance exercise: is inflammation the cause? a cardiovascular magnetic resonance study

BACKGROUND

The aetiology and clinical significance of troponin release following endurance exercise is unclear but may be due to transient myocardial inflammation. Cardiovascular magnetic resonance (CMR) affords us the opportunity to evaluate the presence of myocardial inflammation and focal fibrosis and is the ideal imaging modality to study this hypothesis. We sought to correlate the relationship between acute bouts of ultra endurance exercise leading to cardiac biomarkers elevation and the presence of myocardial inflammation and fibrosis using CMR.

METHODS

17 recreation athletes (33.5 +/- 6.5 years) were studied before and after a marathon run with troponin, NTproBNP, and CMR. Specific imaging parameters to look for inflammation included T2 weighted images, and T1 weighted spin-echo images before and after an intravenous gadolinium-DTPA to detect myocardial hyperemia secondary to inflammation. Late gadolinium imaging was performed (LGE) to detect any focal regions of replacement fibrosis.

RESULTS

Eleven of the 17 participant had elevations of TnI above levels of cut off for myocardial infarction 6 hrs after the marathon (0.075 +/- 0.02, p = 0.007). Left ventricular volumes were reduced post marathon and a small increase in ejection fraction was noted (64+/- 1% pre, 67+/- 1.2% post, P = 0.014). Right ventricular volumes, stroke volume, and ejection fraction were unchanged post marathon. No athlete fulfilled criteria for myocardial inflammation based on current criteria. No regions of focal fibrosis were seen in any of the participants.

CONCLUSION

Exercise induced cardiac biomarker release is not associated with any functional changes by CMR or any detectable myocardial inflammation or fibrosis.