Single-blinded Randomized Investigator-initiated Controlled Trial to Assess the Efficacy of Colchicine to Treat Patients With Cardiomyopathy With Myocarditis (Chronic Inflammatory Cardiomyopathy)

In a proportion of patients, myocarditis, an inflammatory injury of cardiomyocytes (CMs), can lead to chronic inflammatory cardiomyopathy (Infl-CMP) characterized by an increased risk of life-threatening ventricular arrhythmias (VA) or ventricular dysfunction and heart failure (HF). Most cases of myocarditis have a viral trigger or an autoimmune etiology, while genetic predisposition has been sporadically reported. Recent data point to a relevant role of genetics, with pathogenic genetic variants associated with dilated or arrhythmic cardiomyopathies found in 8-31% of patients with Infl-CMP and left ventricular (LV) systolic dysfunction. Occasionally, patients with myocarditis may have a positive family history of cardiomyopathy, or sudden cardiac death (SCD), which can lead to genetic testing for myopathic cardiac gene variants (MCGV). Small series showed the co-existence of myocarditis and MCGV in patients with dilated cardiomyopathy. In this complex background, it is still unclear whether targeting myocardial inflammation with immunomodulating drugs can ameliorate the outcome of these patients.

TRIAL - The Investigators will conduct a Trial to assess whether in patients with Infl-CMP with VA or HF phenotype, colchicine compared with placebo can reduce myocardial inflammation improving the clinical condition of patients. In the trial both patients with positive MCGV and negative MCGV will be randomized, and the investigators check if the genetic background can affect the response to colchicine. The target of this pilot trial is to randomize 40 patients in each arm and have ideally 15 patients with MCGV(+) in each arm. The use of colchicine in our proposal of trial relies on the safety of colchicine, and the relatively low rate of side effects at low dosages. It has shown that colchicine performs its functions by inhibiting the activation of pore formation carried out by P2X2 and P2X7 receptors, that concur to the activation of the inflammasome, thus potentially targeting a specific cause observed in Infl-CMP.

In a pilot, randomized, and single-blinded trial the investigators look at the immunomodulating effect of colchicine 0.5-1 mg vs. placebo in patients with Infl-CMP based on cardiac magnetic resonance imaging (CMRI) or fluorodeoxyglucose (FGD)-positron emission tomography (PET) scan with VA (including high premature ventricular complexes [PVC] burden), reduced LV ejection fraction (EF), or significantly increased levels of natriuretic peptides but without indication to immunosuppression (i.e., associated systemic autoimmune disorders) to assess whether colchicine can improve myocardial inflammation or decrease troponin release or the burden of PVCs or improve the clinical outcome (major VA, HF hospitalizations). The duration of the trial will be 6 months. The rationale of the pilot (CMP-MYTHiC CardioMyoPathy with MYocarditis THerapy with Colchicine) trial is based on a recent registry of 55 symptomatic patients with >5000 premature ventricular complexes (PVCs)/24 hours with FDG-PET imaging consistent with Infl-CMP, where a signal of benefit was observed in patients who received prednisone 40 mg for 3 months. The benefit was defined as a reduction in the PVC burden >80% and negative FDG-PET scan at follow-up. It must be noted that up to 24% of these cases had a diagnosis of sarcoidosis, where there is already an indication to therapy with steroids. In this study (MAVERIC registry) the improvement of patients treated with prednisone alone was 84% vs. 33% in patients not taking prednisone. As the investigators expect a lower effect of colchicine compared with prednisone but with a safer drug profile than prednisone, the investigators considered a theoretical optimal response in patients taking colchicine of 66%, while the investigators expected a similar optimal response in patients taking placebo as in the MAVERIC registry in patients not taking prednisone. Thus, considering an increase in the probability to reach the primary endpoint, defined as proportion of patients that are alive and free of any worsening (clinical, arrhythmic burden and imaging outcome) and that shows at least one of the signs of improvements (IMAGING or ARRHYTMIC improvements) at 6 months from 33% in the placebo arm to 66% in the colchicine therapy arm, the planned sample size of 80 patients (40 per group) will allow achieving a power of 0.80 with an overall type I error of 0.025 using one-sided Fisher's Exact test.

Endpoints will be analyzed according to the following principles:

1. Intention-to-treat (ITT) population: patients according to assigned randomized treatment arm.
2. Per Protocol (PP) population: only patients allocated to the colchicine therapy arm who took the drug for at least 4 months will be considered in the experimental group. Patients assigned to the colchicine therapy arm that will receive less than 4-month colchicine therapy will be excluded from this population. Likely, patients allocated to the optimal medical therapy with placebo will be included if they have taken the placebo therapy for at least 4 months. Patients allocated to the treatment or placebo that will receive any immunosuppressive agents (e.g. corticosteroids) for at least 1 month during the trial will be excluded from this population.
3. A sensitivity analysis will also be performed on the previously defined populations after excluding patients (1) with an implantable cardioverter defibrillator (ICD) before randomization (2) who underwent a ventricular ablation before randomization (3) who were diagnosed with a systemic autoimmune disorder or a histological diagnosis of eosinophilic myocarditis, cardiac sarcoidosis or giant cell myocarditis after the randomization.