Genetic Characterization of Patients With Arrhythmia-Induced Cardiomyopathy

The goal of this observational study is to learn about the genetic insights of arrhythmya-induced cardiomyopathy and its clinical prognosis. The main questions it aims to answer are:

I. Does patients with arrhythmia-induced cardiomyopathy have a greater proportion of genetic mutations compared with other types of cardiomyopathy or general population? II. Have the genetics any prognostic impact in patients with arrhythmia-induced cardiomyopathy?

This is a multicentric prospective observational study including patients with suspected arrhythmia-induced cardiomyopathy (AiC) and undergoing rhythm control strategy. AiC suspicion is defined by the presence of left ventricular ejection fraction \<50% with no other more plausible explanation than a new-onset arrhythmia.

Patients who met the inclusion/exclusion criteria will be followed during 1 year after the rhythm control procedure (electric cardioversion or catheter ablation) to asess rhythm control status, imaging remodeling and clinical events. A genetic test will be performed during the study time to asess the existace of genetic variants in cardiomyopathy-related genes. Follow-up visits will be scheduled at 2, 6 and 12 months after inclusion and electrocardiogram and echocardiography will be performed.

AiC will be confirmed in case of left ventricular ejection fraction recovery \>10% or absolute value \>54% during the follow up imaging evaluations.

Primary analysis will asess the prevalence of pathogenic /likely patogenic variants in patients fullfilling AiC criteria and compared with those who not (without AiC). Secondary analysis will be focused on the incidence of cardiovascular events (heart failure-related and rhythm control-related) during the follow up and its relationship with the genetic background and the AiC status.

Imaging test during follow up will be performed and changes in ventricular and atrial parameters will be used to asess cardiac remodeling.

Further rhythm control asessment will be performed following routinary clinical practice in each participant center.

Eligibility Criteria:
Inclusion Criteria:

* Presence of atrial fibrillation or atrial flutter not self-limited.
* Performance of a cardiac imaging test with systolic function analysis (echocardiogram, magnetic resonance, CT scan) during the clinical course of the arrhythmia, exhibiting a left ventricular ejection fraction (LVEF) \<50%. In order for the test to be representative, the maximum time between the performance of the imaging test and the rhythm control procedure will be 3 months, in the absence of intervening cardiovascular events that may have caused a variation in LVEF. In the event that the patient had a previously known LVEF \<50%, the change with respect to this attributable to tachyarrhythmia has to be ≥10%.
* Signature of informed consent.
* Ability to understand and accept participation in the study.

Exclusion Criteria:

* Refusal of informed consent.
* Legal or juridical incapacity.
* Age \<18 years.
* Life expectancy less than 1 year.
* Impossibility of a follow-up of at least 6 months.
* Presence of a ventricular rate \>140 beats per minute, limiting the validity of imaging measurements.
* Presence of known factors causing systolic ventricular dysfunction:

  * Prior cardiomyopathy diagnosis.
  * Severe mitral or aortic valve disease.
  * Non-revascularizable ischemic heart disease.
  * Context of peri-resuscitation cardiopulmonary care.
  * Abusive alcohol consumption, defined as \>80 grams of ethanol or \>7 standard alcoholic beverages per day.
  * Active treatment with chemotherapeutic agents or radiation therapy to the thorax.
  * Known infection with Trypanosoma cruzi, Borrellia burgdorferi or other infectious agent causing cardiomyopathy.