Novel Cardiac Imaging Prognostic Markers of Clinical Outcome in Patients With Chronic Aortic Regurgitation
Novel Cardiac Imaging Prognostic Markers of Clinical Outcome in Patients With Chronic Aortic Regurgitation
Severe aortic regurgitation is a common valvular heart disease with prevalence of
 approximately 1%, affecting rather younger patients. The surgical treatment is the only
 causal treatment; it is recommended in patients with severe symptomatic aortic regurgitation.
 The optimal timing of the surgery is crucial because there is a certain risk of perioperative
 mortality and most patients require lifelong anticoagulation therapy. It is widely accepted,
 that asymptomatic patients with severely dilated left ventricle with systolic impairment have
 worse postoperative prognosis. We aim to evaluate native myocardial T1 relaxation time
 derived from cardiac magnetic resonance and global longitudinal left ventricular strain
 measured by echocardiography. These parameters are related to diffuse myocardial fibrosis and
 we expect to identify the cut off values, which correlate with further clinical course. This
 might enable better timing of the surgical treatment with the optimal postoperative left
 ventricular reverse remodelling and improved patient prognosis.
Introduction:

 Chronic aortic regurgitation is a common valvular heart disease with prevalence of
 approximately 1% in European population; affecting rather younger patients. The most common
 causes of chronic aortic regurgitation in developed countries are calcific aortic valve
 disease and bicuspid aortic valve. Another relatively frequent cause of the chronic aortic
 regurgitation is the aortic root dilation, which is genetically determined and it is also
 frequently diagnosed in younger patients. According to current guidelines for valvular heart
 disease, surgical treatment is recommended for patients with the severe symptomatic aortic
 regurgitation and for patients with the severe asymptomatic aortic regurgitation when left
 ventricular ejection fraction (LV EF) is < 50% or if other cardiothoracic surgery is planned
 (Class I). Current guidelines also recommend considering surgical strategy (Class IIa) in
 asymptomatic patients with severe aortic regurgitation, left ventricular ejection fraction
 (LV EF) ≥ 50% and left ventricular end-systolic diameter > 50 mm or indexed diameter > 25
 mm/m2. There are two reasons for considering this earlier surgical treatment. Surgical
 techniques and perioperative treatment have improved recently and postoperative patient
 outcome are significantly better. There is also strong evidence that left ventricular (LV)
 diameter decreases shortly after surgery but left ventricular ejection fraction (LV EF)
 remains unchanged in majority of patients and left ventricular ejection fraction (LV EF) is
 one of the main determinants of patient's future quality of life and life expectancy.
 However, surgical correction might be indicated too late in clinical practice, typically in
 women. The Mayo Clinic authors group reported that women exhibit an excess late mortality
 compared to male population. They showed that women were severely symptomatic at the time of
 surgery compare to male population where left ventricular (LV) enlargement was more frequent.
 Bonow at al reported 33% incidence of clinical events, death and deterioration of left
 ventricular ejection fraction (LV EF), in natural history of asymptomatic patients with
 severe aortic regurgitation and preserved left ventricular ejection fraction (LV EF).

 The optimal timing of surgical treatment is crucial but it has not been clearly established
 yet. New methods of identifying subclinical left ventricular (LV) function impairment are
 needed for better timing of the surgical strategy. Clinical follow-up with routine
 echocardiography study is recommended every 6 to12 months in patients with severe
 asymptomatic aortic regurgitation because sudden deterioration of left ventricular (LV)
 function might occur and we aim to operate on our patients before this happens. It is clear
 other parameters are needed than only left ventricular ejection fraction (LV EF) and left
 ventricular (LV) size. Diffuse myocardial fibrosis is a common feature of pathophysiology of
 the chronic left ventricular (LV) overload. Left ventricular ejection fraction (LV EF) and
 left ventricular (LV) size are less sensitive and non-specific markers of this process.
 Fortunately several novel methods of non-invasive quantification of the diffuse myocardial
 fibrosis have been introduced recently. The most promising method is the magnetic resonance
 imaging (MRI) - derived T1 relaxation time mapping introduced by Messroghli in 2004, Modified
 Look-Locker inversion recovery (MOLLI) sequence. Based on published data, MRI derived native
 T1 relaxation time is a reliable marker of diffuse myocardial fibrosis. The native T1
 relaxation time with cut off value of ≥ 1010 ms is an accurate marker of extensive (>30%)
 myocardial fibrosis with high sensitivity and specificity (Ss=90%, Sp=73%, area under curve
 (AUC) =0.82). Extracellular myocardial volume (ECV) calculated from MOLLI sequence is also a
 sensitive marker of diffuse myocardial fibrosis and extracellular myocardial volume (ECV)
 cutoff value of ≥ 0.315 showed high accuracy to identify extensive (> 30%) myocardial
 collagen content (Ss=80%, Sp=90%, AUC =0.85). Speckle tracking echocardiography is another
 promising imaging method for diffuse myocardial fibrosis. Two-dimensional LV global
 longitudinal strain (GLS) has a potential to discover subclinical left ventricular (LV)
 functional impairment

 Project Plan:

 1. All patients will be scanned by MRI including Modified Look-Locker inversion recovery
 (MOLLI) within one week after inclusion and all complete and anonymized studies will be
 sent to CoreLab in IKEM. Off-line analysis will consist of the left and right ventricle
 volumetric and ejection fraction assessment. The aortic regurgitation will be measured
 using methods of flow sequence at sinotubular junction level (phantom correction
 required) and ventricular stroke volume difference. Modified Look-Locker inversion
 recovery (MOLLI) sequence will be acquired before, 10 and 15 minutes after contrast
 agent administration. T1 relaxation time will be measured within interventricular septum
 and ECV will be calculated from T1 relaxation time of the myocardium and the blood pool.
 Off-line analysis will be performed by two independent operators blinded to clinical and
 ECHO findings and intra- and inter-observer variability will be calculated.

 2. All patients will undergo 2-D and 3-D transthoracic echocardiography within one week
 after inclusion and every six months during follow-up in each participating centre. All
 full volume anonymized studies will be sent to the CoreLab in IKEM. Off-line analysis of
 the left ventricular ejection fraction (LV EF),left ventricular (LV) volume, left
 ventricular (LV) mass, speckle tracking left ventricular (LV) global longitudinal strain
 (GLS), radial strain and left ventricular (LV) twist will be performed by two
 independent operators in a blinded fashion. Similarly aortic regurgitation grade will be
 assessed by two operators using colour Doppler, vena contracta measurement, and Doppler
 flow measurements. Inter- and intra-observer variability will be than calculated.

 3. In all patients 12-lead electrocardiogram (ECG) will be recorded and blood sample will
 be taken during each visit. Brain natriuretic peptide serum level will be measured
 routinely at each participating centre. One blood sample will be stored frozen at -80 C°
 for further analysis including for example galectin levels, etc. This specific analysis
 will be performed in 1.Faculty of Medicine Charles University in Prague under the
 supervision of Prof. Sedmera.

 4. Sub-study.

 1. All patients who will be scheduled for aortic valve surgery during follow-up
 (strictly according to current guidelines) will undergo perioperative myocardial
 needle biopsy from interventricular septum in each participating centre. All
 myocardial samples will be processed and analysed in 1.Faculty of Medicine Charles
 University in Prague under the supervision of Prof. Sedmera.

 2. All patients who will be scheduled for aortic valve surgery during follow-up will
 undergo repeat magnetic resonance imaging (MRI) study including Modified
 Look-Locker inversion recovery (MOLLI) sequence within 1-3 months prior to the
 operation and 6-12 month after the operation. The complete study will be repeated
 as described above. Postoperative left ventricular (LV) remodelling will be
 precisely assessed by off-line analysis. A correlation of the left ventricular (LV)
 remodelling and preoperative regurgitation grade as assessed by magnetic resonance
 imaging (MRI) and echocardiography (ECHO) will be calculated. Postoperative left
 ventricular (LV) remodelling will be also correlated with preoperative T1
 myocardial relaxation time, extracellular volume (ECV) and global longitudinal
 strain (GLS).

 Project Hypothesis:

 1. We hypothesize that the increased native T1 longitudinal relaxation time as assessed by
 T1 mapping (Modified Look-Locker inversion recovery sequence) > 1010 ms and decreased
 global longitudinal strain (GLS) < 17 % are novel potent prognostic markers of clinical
 deterioration in patients with moderate to severe and severe chronic asymptomatic aortic
 regurgitation despite preserved left ventricular ejection fraction (LV EF).

 2. We hypothesize that inter- and intra-observer variability of the aortic regurgitation
 severity assessment will be lower for the magnetic resonance imaging (MRI) study than
 for the echocardiography (ECHO) study.

 3. We hypothesize that the degree of postoperative left ventricular (LV) recovery (decrease
 of the left ventricular (LV) volume and left ventricular (LV) mass) will correlate
 better with preoperative magnetic resonance imaging (MRI) regurgitation grade assessment
 rather than with echocardiography (ECHO) derived grade.

 CoreLab The CoreLab will be located in Institute for Clinical and Experimental Medicine
 (IKEM) centre. All full volume anonymized magnetic resonance imaging (MRI) and 2-D and 3-D
 echocardiography (ECHO) studies will be sent to this CoreLab for off-line analysis. Two
 independent operators, specialists in the field of magnetic resonance imaging (MRI) and
 echocardiography (ECHO), will review all studies in a fully blinded fashion. One operator
 will repeat the analysis at least one month after the first reading. Inter- and
 intra-individual variability will then be calculated.

 Myocardial biopsy and histology Myocardial sample will be obtained by experienced surgeon in
 all patients undergoing cardiothoracic surgery of the aortic valve. Under visual control a
 deep myocardial needle (SuperCore™ Semi-Automatic Biopsy Instrument 16 gauge x 9 cm) biopsy
 will be performed from the basal interventricular septum via the left ventricular outflow
 tract approach. A myocardial sample will be immersed immediately in 10% buffered formalin,
 embedded in paraffin blocks and later on sectioned at 3 micrometres (μm) thickness and
 stained with Picrosirius Red (PSR). PSR is a collagen specific stain and is an optimal tool
 for collagen quantification using normal light and also polarized light, which is helpful to
 distinguish between new and more matured collagen fibres. Percentage of myocardial fibrosis
 will be calculated as the ratio of Picrosirius Red (PSR)-positive area over total area using
 Image J software with differential thresholding. Histology analysis will be performed by
 experienced specialist on this field in a fully blinded fashion.

 Laboratory analysis Fasting blood samples will be obtained during each visit and serum level
 of Hemoglobin, C-reactive protein, Hemoglobin A1c, Creatinine and Glucose level, Brain
 Natriuretic Peptide, Galectin 1 and 3 level will be measured. Creatinine clearance will be
 calculated using Cockcroft-Gault equation. One sample of frozen plasma will be stored for
 further analysis (but not for genetic analysis).

 Number of included patients 100 - 150 patients in total.

 Data Collection Patient data will be collected in one database system shared on-line with all
 centres. It will require an identification code for a patient and a centre. Under no
 circumstances will the patient data such as name, identification number (ID), address or
 other contact details be collected.

 Study duration 2016 - 2022 (2 years recruitment + 5 years follow-up)
Inclusion Criteria

 1. Chronic asymptomatic aortic regurgitation grade 3 (moderate to severe) and grade 4
 (severe)

 2. No indication for the surgical treatment at the time of enrolment

 3. LV EF ≥ 50 %

 4. Absence of more than mild concomitant valve disease or complex congenital heart
 disease

 Exclusion Criteria

 1. Age < 18 years

 2. Clearance Creatinine < 30 mL/min

 3. Contraindication of magnetic resonance (implanted active device, ferromagnetic implant
 incompatible with magnetic resonance scanner, aneurysm clip, metallic fragment in the
 eye or near sensitive tissue)

 4. Pregnancy