Systemic Lupus Erythematous and Heart Conduction Disorders

We designed a cross-sectional study for an observational analysis. The target population will be the group of SLE patients visited the service of Rheumatology hospitals in Catalonia (Spain).

The criteria for subjects selection to participate in our project are:

1 . Inclusion criteria: patients with SLE according to established diagnostic criteria in 1997 2. Exclusion criteria:

• Presence of cardiac: Ischemic heart disease or congenital or acquired structural heart disease (hypertrophic cardiomyopathy, idiopathic dilated cardiomyopathy, valve disease with clinical significance).
• Background heart surgery or cardiac ablation procedures.
• Background in other pathological processes has been described affecting cardiac conduction tissue: Steinert's disease, Lyme disease, Chagas' disease with heart involvement or hypothyroidism.

The selection of patients and controls are done through a sampling of consecutive patients seen in our outpatient rheumatology center to achieve the sample size. This has been fixed in two subgroups: 100 patients with SLE and positive for anti-Ro (with positivity for anti-Ro only 52 or positivity for anti-Ro and anti-Ro 52 60) and 50 patients (controls ) with SLE and negative for anti-Ro (anti-Ro52 and anti-Ro 60).

As defined as primary variables, the study of cardiac conduction disorders will be done through the analysis of resting electrocardiogram (ECG) and a 24-hour Holter.

Other descriptive variables are listed below:

• Collection of general medical history of patients, with emphasis on Rheumatology and cardiac involvement.
• Check the current medication.
• Height and weight.
• Physical examination.
• 12-lead resting ECG with analysis of rate base, as well as the duration of the PR interval, QRS and QT. Analysis of the presence of intraventricular conduction disorders and the presence of ectopic beats.
• Record 24-hour Holter Presence and number of ventricular ectopic beats, classification of events according to the Lown's criteria. Presence of significant pauses (RR interval> 2000mseg). Measurement of corrected QT (QTc).
• Presence of autonomic dysfunction parameters: time domain parameters such as the mean RR interval, standard deviation of all normal RR intervals (SDNN), the root of the mean difference between successive adjacent normal RR intervals (RMSSD ) and the percentage of adjacent intervals over 50mseg (PNN50)
• Echocardiography to rule out structural heart disease: Analysis of ventricular diameters and systolic and diastolic function, presence of significant valve disease, pulmonary systolic pressure, pericardial effusion and other congenital or acquired structural heart disease.
• Analysis with serologic immune profile, determining the degree of organic involvement by SLE

Inclusion criteria

• Patients with SLE diagnosis, according to SLE diagnostic criteria.

Exclusion criteria

• Patients with previous cardiac diseases (ischemic heart disease, hypertrophic cardiomyopathy, dilated cardiomyopathy, valvular heart disease)
• Clinical history of heart surgery or ablation procedures
• Clinical history of other conditions that affect heart conduction:

• Steinert Disease
• Lyme Disease
• Chagas Disease
• Hypothyroidism