The identification of myocardial fibrosis in term of myocardial scar and extracellular matrix remodelling assessed respectively with the technique of Late Gadolinium Enhancement (LGE) and with the quantification of the Extracellular Volume Fraction (ECV) in Cardiac Magnetic Resonance has been demonstrated to be crucial in the diagnosis of different cardiomyopathy and to be prognosticators of major cardiovascular adverse events [1-14].

For these reason CMR represent the gold standard for the non-invasive characterization of myocardial tissue in the clinical practice.

However, regardless of its indisputable clinical role, CMR has many limitations: 1) it does not allow to evaluate coronary arteries; 2) it is contraindicated in patients with cardiac devices, and in case of conditional device they may also significantly impair LGE assessability due to artefacts [19]); 2) has limited availability and it is time consuming, therefore it is difficult to perform in the acute setting also because of poor patient compliance; 3) it is not feasible in patients suffering from claustrophobia. Cardiac Computed Tomography (cCT) is the image of choice to non-invasively study coronary arteries, not assessable with CMR. Moreover the recent technological advancement has continuously increased the clinical indication to the evaluation of cardiac valve and fibrosis, with reduced acquisition time respect to CMR (few minutes vs 1 hour), radiation exposure and costs.

cCT has emerging as a possible alternative to CMR in the characterization of myocardial scar and extracellular volume fraction, with the advantage of a single shot evaluation of coronary arteries and myocardial tissue remodelling (scar, diffuse fibrosis, contractility..).In particular, several studies including some from our group, have demonstrated the clinical utility of myocardial tissue characterization with cCT in different clinical settings, such as myocardial infarction [20, 21], myocarditis [22], hypertrophic cardiomyopathy (HCM) [23], heart failure [24], ventricular tachycardia [25], and sarcoidosis [26]. Despite the interesting results, all these previous studies are limited on highly selected and small sample size. Moreover, any large study with long term follow-up is available in the setting of tissue characterization (myocardial scar and ECV) in cCT also as well as combined with a multiparametric approach (cardiac chamber morphofuntionality,contractility-strain, valve calcification, geometry, coronary atherosclerosis, myocardial perfusion, myocardial strain and texture) and no data are available about its prognostic impact. Aim of the study is to evaluate the potential of cCT in tissue characterization (myocardial scar and ECV) alone and associate to other CT imaging biomarker on a large population of patient clinically candidate to cardiac CT.

Inclusion Criteria:

• age ≥ 18 years;
• no contraindication to cCT
• signed informed consent
• clinical indication to cCT for the following reason: stable angina, heart failure, atrial/ ventricular arrhythmias, acute chest pain with need of "triple-rule-out" scan, planning of valvular repair/substitution, structural and infiltrative cardiomyopathy, new onset ECG alteration, troponin increase.

Exclusion Criteria:

• age < 18 years
• pregnancy and/or breastfeeding
• contraindications to iodinated contrast agent administration or impaired renal function (eGFR ≤ 30 mL/min);
• inability to sustain a brief breath hold (5 seconds)

This is a monocentric observational study with a retrospective and a prospective arms.

Patients will be recruited from the Radiology Department of our Institution (IRCCS Ospedale San Raffaele, Milan, Italy). Written informed consent will be obtained.