Role of Endomyocardial Biopsy and Aetiology-based Treatment in Patients With Inflammatory Heart Disease in Arrhythmic and Non-arrhythmic Clinical Presentations: an Integrated Approach for the Optimal Diagnostic and Therapeutic Management
Role of Endomyocardial Biopsy and Aetiology-based Treatment in Patients With Inflammatory Heart Disease in Arrhythmic and Non-arrhythmic Clinical Presentations: an Integrated Approach for the Optimal Diagnostic and Therapeutic Management
Myocarditis is a complex inflammatory disease, usually occurring secondary to viral
 infections, autoimmune processes or toxic agents. Clinical presentations are multiple,
 including chest-pain, heart failure and a broad spectrum of arrhythmias. In turn, outcome is
 largely unpredictable, ranging from mild self-limiting disease, to chronic stage and
 progressive evolution towards dilated cardiomyopathy, to rapid adverse outcome in fulminant
 forms. Subsequently, myocarditis is often underdiagnosed and undertreated, and optimal
 diagnostic and therapeutic strategies are still to be defined. This study, both retrospective
 and prospective, originally single-center and subsequently upgraded to multicenter, aims at
 answering multiple questions about myocarditis, with special attention to its arrhythmic
 manifestations.

 1. Optimal diagnostic workflow is still to be defined. In fact, although endomyocardial
 biopsy (EMB) is still the diagnostic gold standard, especially for aetiology
 identification, it is an invasive technique. Furthermore, it may lack sensitivity
 because of sampling errors. By converse, modern imaging techniques - cardiac magnetic
 resonance (CMR) in particular - have been proposed as alternative or complementary
 diagnostic tool in inflammatory heart disease. Other noninvasive diagnostic techniques,
 like delayed-enhanced CT (DECT) scan or position emission tomography (PET) scan, are
 under investigation.

 2. Biomarkers to identify myocarditis aetiology, predisposition, prognosis and response to
 treatment are still to be defined.

 3. Arrhythmic myocarditis is largely underdiagnosed and uninvestigated. Importantly,
 myocarditis presenting with arrhythmias requires specific diagnostic, prognostic and
 therapeutic considerations. At the group leader hospital, which is an international
 referral center for ventricular arrhythmias management and ablation, a relevant number
 of patients with unexplained arrhythmias had myocarditis as underlying aetiology. The
 experience of a dedicated third-level center is going to be shared with other centers,
 to considerably improve knowledge and management of arrhythmic myocarditis.

 4. The role of CMR, as well as alternative noninvasive imaging techniques, in defining
 myocarditis healing is a relevant issue. In particular, optimal timing for follow-up
 diagnostic reassessment is still to be defined, in patients with myocarditis at
 different inflammatory stages, either with or without aetiology-dependent treatment.

 5. Uniformly-designed studies are lacking, to compare myocarditis among different patient
 subgroups, differing by variables like: clinical presentations, myocarditis stage,
 associated cardiac or extra-cardiac diseases, aetiology-based treatment, associated
 arrhythmic manifestations, diagnostic workup, and devices or ablation treatment.
This study, previously designed as a single-center experience, is multicenter, observational
 and both retrospective and prospective.

 Retrospective phase includes all clinical data occurring before the index event
 (hospitalization or clinically suspected myocarditis) and myocarditis diagnosis. Prospective
 phase includes all data following index event and myocarditis diagnosis.

 This study has multiple aims.

 1. To compare EMB with noninvasive diagnostic techniques (CMR, DECT, PET scan, either alone
 or in association).

 2. To assess the role of blood biomarkers for identification of aetiology, predisposition,
 prognosis, response to treatment, inflammatory activity, clinical presentation.

 3. To describe myocarditis presenting with arrhythmias, with special focus on ventricular
 arrhythmias at different myocarditis stages and in different clinical contexts. To
 validate and generalize the leader hospital model for optimal diagnostic and
 therapeutical management of arrhythmias in myocarditis patients (given the role of the
 leader hospital as an international referral center for arrhythmias ablation and
 management).

 4. To evaluate the timing needed for myocarditis healing in different patients subgroups,
 as assessed by noninvasive imaging techniques (CMR, DECT, PET scan), either alone or in
 association.

 5. To compare patients subgroups of myocarditis, in terms of epidemiology, aetiology,
 prognosis, and diagnostic-therapeutical strategies. Among the others, the main study
 subgroups will be:

 A. Arrhythmic vs. non-arrhythmic myocarditis. B. Arrhythmic myocarditis subgroups. C.
 Non-arrhythmic myocarditis subgroups (i.e.: fulminant, acute coronary syndrome-like,
 pericarditis-like, heart failure, nonischaemic dilated /hypokinetic cardiomyopathies of
 unknown aetiology…).

 D. Infectious vs. autoimmune vs. toxic myocarditis. E. Myocarditis treated by aetiology-based
 treatment vs. isolated cardiac medical treatment.

 F. Myocarditis at different disease stages: acute, hyperacute, fulminant, chronic active,
 post-inflammatory, or active vs. previous vs. non-myocarditis.

 G. Myocarditis presenting as organ-specific diseases vs. in the context of a genetic disorder
 or systemic disease.

 H. Myocarditis vs. peri-myocarditis/myo-pericarditis. I. Other analyses.

 Any adult patient with clinically suspected myocarditis, of any clinical presentation and any
 degree of severity, will be considered as suitable for study enrollment.

 Patients will undergo diagnostic and therapeutical strategies considered as clinically
 indicated in a patient-tailored manner, as suggested by international guidelines
 recommendations and best local clinical practice. Patients will be free of either accepting
 or refusing any diagnostic or therapeutical proposal. Whenever accepted, data will be simply
 collected and analyzed.

 Based on clinical presentation, patients will be divided into two groups, arrhythmic (group
 A) and non-arrhythmic (group NA, including any other clinical presentation).

 Independently of A/NA groups, all patients will undergo optimal diagnostic and therapeutic
 strategies, as summarized in panel A. In parallel, special diagnostic and therapeutical
 strategies will be performed in patients with arrhythmic presentation or evidence of
 arrhythmias, as shown in panel B. Proposed flowcharts (Panels A and B) represent only an
 approximate algorithm. Exceptions can be made in single cases, based on clinical indications.

 Panel A - Diagnostic and therapeutical workup in all patients. Independently of groups
 (A/NA), all patients will undergo optimal diagnostic and therapeutical workup, guided by
 updated scientific evidence merged with the clinical experience of the center.

 Baseline diagnostic workup will include: complete blood exams, 12-leads ECG, continuous
 telemetric monitoring, transthoracic doppler echocardiogram, coronary artery imaging
 (coronary angiography or CT scan). Any other clinically relevant diagnostic test will be
 collected.

 In life-threatening presentations (cardiogenic shock or malignant arrhythmias), support
 treatment by optimal medical therapy, inotropic or mechanical circulatory support, and
 acute-phase arrhythmia management (including cardioversion, defibrillation, or temporary
 pacing) will be performed, as indicated, before completing diagnostic workup.

 Final diagnosis of myocarditis will include, whenever applicable:

 A. For stable patients: 1) a second-level imaging technique (CMR as first choice; and/or
 DECT, PET, or multiple/fusion imaging techniques, based on clinical indications); followed
 by: 2) EMB, whenever clinically indicated. Blood exams for aetiology screening will be
 personalized upon clinical indications.

 B. For unstable patients: EMB only, as recommended. Blood exams for aetiology screening will
 be personalized upon clinical indications.

 Diagnostic criteria for myocarditis, as assessed by any diagnostic technique, will be defined
 based on international scientific evidence and will be constantly updated. Similar
 considerations apply to myocarditis staging and aetiology definition. Whenever not available
 at local institutions, diagnostic exams can be performed and analyzed at external centers.

 All patients with myocarditis (or any alternative final diagnosis), will undergo standard
 cardiological optimal medical treatment (COMT), as indicated. By converse,
 aetiology-dependent treatment will be performed only in patients with a final diagnosis of
 any active (acute, fulminant, chronic active) myocarditis of defined aetiology (EMB-proved).
 Multidisciplinary assessment, including infective disease specialists (in viral/infective
 myocarditis), immunologists (in non-infective/autoimmune myocarditis) or any other specialist
 as needed, will be used to identify indications to treatment, drug choice (either approved or
 with a justified unapproved indication), treatment duration and safety profile, aiming at the
 best patients' interest. Toxic myocarditis will be treated accordingly, by evaluating the
 opportunity of withdrawing pathogenic noxa.

 This protocol will not interfere with local best clinical practice. Patients with non-active
 myocarditis (previous or healed) or with non-myocarditis, will undergo "standard FU" (see
 below). Patients with active myocarditis will undergo "intensive FU" (see below).

 Independently of FU modalities, diagnostic reassessment will be considered in the presence of
 at least one of the following instability criteria: a) new unexplained cardiac symptoms
 (dyspnoea, chest pain, syncope, palpitation); b) new unexplained increase in troponin or
 natriuretic peptides; c) new imaging abnormal signs; d) new unexplained clinically relevant
 arrhythmias. Diagnostic reassessment will include second-level imaging and/or EMB, as shown
 above. Subsequent therapeutical workup will be in line with the above explanations. In stable
 patients or undergone myocarditis healing, exercise stress test will be obtained, whenever
 possible.

 Panel B - Diagnostic and therapeutical workup of patients with arrhythmias In parallel with
 (and independently of) Panel A content, patients with arrhythmias (group A) will undergo
 specific diagnostic and therapeutical management for arrhythmias, as a result of the
 integration between international guidelines recommendations and the experience of an
 international referral center for arrhythmia management and ablation.

 To oversimplify, 4 groups of patients will be considered.

 1. Group 1: major ventricular arrhythmias, including haemodynamically unstable VT (hu-VT)
 and ventricular fibrillation (VF).

 After electrical stabilization and support treatment (panel A), indication to secondary
 prevention ICD implant will be multiparametric and patient-tailored. In patients with
 active myocarditis, subcutaneous ICD (S-ICD) or wearable CD (WCD) will be considered.
 Antiarrhythmic drugs will be considered in all Group 1 patients. In addition, all Group
 1 patients will undergo COMT and aetiology-dependent treatment whenever applicable
 (panel A). Ablation of ventricular arrhythmias will be considered in patients with
 severe arrhythmic presentation, or symptomatic, or refractory to optimal medical
 treatment. Electrophysiological study (EPS) may be used in selected cases. A cardiac
 resynchronization therapy with defibrillator function (CRT-D) will replace ICD whenever
 indicated.

 2. Group 2: other ventricular arrhythmias, including high-burden (hb) premature ventricular
 complexes (PVC); nonsustained VT (NSVT); haemodynamically stable VT (hs-VT).

 Whenever clinically indicated, Group 2 patients will undergo invasive EPS (or in
 alternative noninvasive programmed ventricular stimulation in ICD carriers) to stratify
 arrhythmic risk. Patients with positive EPS will undergo ICD (or S-ICD/WCD) as in Group
 1. Patients with negative EPS, as well as Group 2 cases not undergoing EPS, will undergo
 watchful waiting strategy (always with an intensive FU) with or without loop recorder
 implant: in these cases, ICD (or S-ICD/WCD) will be implanted only following
 documentation of relevant VA in FU. In addition, all Group 2 patients will undergo
 antiarrhythmic treatment, COMT and aetiology-dependent treatment whenever applicable
 (panel A). In symptomatic or drug-refractory cases, ablation of ventricular arrhythmias
 will be considered. A CRT-D will replace ICD whenever indicated.

 3. Group 3: bradyarrhythmias, including advanced (2nd type II or 3rd degree)
 atrioventricular block (AVB); critical sinus pauses from sinus node disease (SND).

 After electrical stabilization and support treatment (panel A), including the use of
 temporary pacemaker as a bridge-to-decision, patients will undergo watchful waiting
 strategy or definitive device implant. Instead of a pacemaker (PM), ICD will be
 considered in the presence of high-risk criteria for ventricular tachyarrhythmias,
 including: a) overlap with Group 1 presentation; b) overlap with Group 2 presentation,
 especially in the presence of positive EPS; c) other indications for primary prevention
 ICD implant (severe systolic dysfunction); d) signs of increased tachyarrhythmic risk
 (scar signs); e) patients with special aetiologies leading to an increased
 tachyarrhythmic risk (i.e: cardiac sarcoid, giant cell myocarditis, Chagas disease,
 overlapping genetic syndromes). In addition, all Group 3 patients will undergo COMT and
 aetiology-dependent treatment whenever applicable (panel A). A CRT-D or a CRT-P will
 replace ICD or PM, respectively, whenever indicated.

 4. Group 4: supraventricular arrhythmias, including atrial fibrillation (AF); atrial
 flutter (AFlu); atrial tachycardia (AT).

 Following acute-phase rate control (RaC), stable rhythm control (RyC) strategy will be
 considered as the therapeutical target, together with appropriate anticoagulation, as
 needed. Normal sinus rhythm will be obtained through either electrical or
 pharmacological cardioversion. In patients with unsuccessful attempts of sinus rhythm
 conversion, optimal treatment of active myocarditis will be considered as a primary
 target. Following myocarditis healing, in the presence of persistent arrhythmias,
 patients will be considered for RyC via electrical or pharmacological cardioversion.
 Transcatheter ablation will be an option for patients with drug-symptomatic, recurrent
 or refractory arrhythmias. Permanent RaC strategy will be considered only in non
 responders. Widespread use of implantable loop recorders will apply, as clinically
 indicated. In addition, all Group 4 patients will undergo COMT and aetiology-dependent
 treatment whenever applicable (panel A).

 Aims in detail. Aim 1 Comparison between EMB and second level imaging findings (N=1000)

 Primary:

 Diagnostic concordance

 Secondary:

 Inflammatory activity (presence; type; quantification) Fibrosis (presence; type;
 quantification) Coronary microvascular disease Comparison between EMB sampling site and
 abnormal substrate localization at imaging (including substrate-guided EMB or
 alternative biopsy techniques) Role of EMB guided by electroanatomical map Diagnostic
 performance of DECT and/or PET, especially when CMR is contraindicated Comparison
 between CMR/DECT findings and PET scan (including fusion imaging) or advanced imaging
 techniques including strain analysis at echocardiogram Comparison between substrate
 abnormalities localizations (as assessed by second level imaging techniques) and
 arrhythmias (type, characteristics and origin site) Comparison among different
 diagnostic techniques (EMB, CMR/DECT, PET) in terms of safety and diagnostic accuracy
 Evaluation of differential diagnosis with other cardias diseases, and particularly with
 arrhythmogenic cardiomyopathy of any localization (left, right, biventricular, to
 identify updated diagnostic criteria) Comparison between information provided by all the
 techniques above, and data from electroanatomical mapping (EAM) Other analyses

 Aim 2 Evaluation of blood exams and biomarkers (N=1000)

 Primary:

 Identification of diagnostic biomarkers Identification of aetiology biomarkers

 Secondary:

 Cardiac and inflammatory biomarkers evaluation in different myocarditis subtypes
 Identification of biomarkers of inflammatory stage (acute vs. chronic; active vs.
 previous) Comparison between local and systemic/peripheral inflammation Correlations
 with EMB and second-level imaging (CMR, DECT, PET…) findings Identification of genetic
 factors with any role in predisposition, prognosis, response to treatment, or any other
 correlation, either in the presence or in the absence of underlying cardiomyopathy or
 autoimmune/inflammatory disease Identification of prognostic biomarkers Identification
 of biomarkers associated with treatment response Evaluation of any tissue/organ damage
 or associated comorbidities Study of cardiac autoantibodies Study of any cell, tissue,
 genetic or circulating biomarker Correlations with clinical presentations Other analyses

 Aim 3 Validation of optimal management of arrhythmic myocarditis (N=1000)

 Primary:

 Evaluation of effects on major endpoints

 Secondary:

 Evaluation of effects on minor endpoints Role of electrophysiological study in risk
 stratification Role of loop recorders in arrhythmia monitoring Role of transcatheter
 ablation (any technique) on arrhythmic outcomes Identification of optimal timing for any
 electrophysiological/device procedure Role of pharmacological antiarrhythmic treatment
 Role of aetiology-specific treatment on arrhythmic outcomes Identification of criteria
 for device implants (PM, ICD, S-ICD, CRT-D…) in myocarditis patients Validation of
 therapeutic strategies and their optimal timing in patients with supraventricular
 arrhythmias, bradyarrhythmias, or ventricular arrhythmias Correlation between arrhythmia
 type/features with any other diagnostic exam performed at baseline or during FU (mainly
 EMB, CMR/DECT/PET, echocardiogram, stress tests, blood exams, genetic/blood/tissue/cell
 biomarkers) Indications and timing for device (ICD, CRT-D) implant in primary
 prevention, based on multiparametric risk assessment, and in relation to different
 general and aetiology-dependent treatments Other analyses

 Aim 4 Evaluation of healing timing in myocarditis (N=500) Primary Any degree of recovery
 by 3, 6, 9, 12 and > 12 months Secondary Comparison of healing times in treated vs.
 untreated patients Correlations between healing times and clinical presentation types
 Correlations between healing times and any biomarker Correlations between healing times
 and any outcomes Validation of exercise stress test role after myocarditis healing
 Evaluation of PET scan or other diagnostic techniques as alternatives to CMR in special
 populations Other analyses

 Aim 5 Subgroup analyses (N=500, hugely variable in each subanalysis) A vs. NA groups; A
 myocarditis subgroups; NA myocarditis subgroups (including fulminant); Infective vs.
 autoimmune vs. toxic forms; Treated by aetiology-driven therapy vs. standard
 cardiological treatment; Different myocarditis stages and differential diagnoses;
 Isolated vs. in the context o a systemic disease or genetic disease; Myocarditis vs.
 perimyocarditis/ myopericarditis Primary Differences in major outcomes Secondary
 Differences in minor outcomes Differences in any biomarker Differences in any diagnostic
 exam Differences in aetiology Differences in predisposition Differences in inflammatory
 activity Differences in pericardial involvement Differences in systemic involvement
 Differences in arrhythmias types and features Differences in clinical presentation
 Differences in treatment response, including novel treatments Validation of local
 aetiology/pathophysiology-dependent treatments Validation of biomarkers and imaging
 techniques in monitoring response to treatment Identification of optimal follow-up
 timeline Other analyses
Inclusion Criteria:

 -  Written informed consent.

 -  Age ≥ 18 years.

 -  Clinically suspected myocarditis.

 -  Enrollment performed by one of the participating Centers.

 Exclusion Criteria:

 -  Absence of written informed consent.

 -  Age < 18 years (paediatric population).