Systemic sclerosis (SSc) is a disease that affects multiple organs, with the heart being frequently affected and correlating with a poor outcome for the patient. Different heart structures can be affected leading to pericardial disease, arrhythmias, conduction system abnormalities, direct myocardial disease such as pulmonary arterial hypertension, myositis, cardiac failure, cardiac fibrosis, coronary artery diseases and, sometimes, primary valvular involvement.
A group of researchers has recently reviewed key studies concerning cardiac arrhythmias and conduction defects in patients suffering from SSc, a wide-ranging report entitled, “Cardiac arrhythmias and conduction defects in systemic sclerosis,” and published in the journal Rheumatology.
According to the researchers, it is increasingly important to be able to identify patients who are at high risk for cardiac arrhythmias, alongside improved therapeutic options for such patients.
Different studies have identified electrocardiographic abnormalities in SSc patients, however, it is not known if these impairments are a result of myocardial involvement in SSc, transient oxygen-supply imbalance, or other mechanisms.
According to the European League Against Rheumatism (EULAR) Scleroderma Trials and Research (EUSTAR) database, among 128 SSc patients, 26% of SSc-related deaths were due to cardiac events. Moreover, a report from the Genetics Versus Environment In Scleroderma Outcome Study (GENISOS) cohort, identified BMI, age, forced vital capacity, blood pressure, pulmonary fibrosis, anti-centromere antibody and cardiac arrhythmias as independent predictors of mortality.
SSc patients were found to have one or more abnormal features (42%) in resting electrocardiogram (ECG), including rhythm disturbances (30%). However, upon 24 hour Holter ECG monitoring, supraventricular arrhythmias (66%), ventricular arrhythmias (90%), multiform ventricular premature beats (40%), pairs of runs of ventricular tachycardia (28%) and one or more runs of ventricular tachycardia (13%) were found in these patients.
In a multicenter ambulatory ECG study, 67% of patients showed ventricular ectopy, correlating with total mortality and sudden death. However, another study reported sudden cardiac death as a small (5%) fraction within the total fatalities observed in SSc patients.
Some electrophysiological abnormalities can only be assessed after specific cardiac workup, such as routine and second-level investigations, and even at an early stage of disease, complete investigation is necessary.
This was demonstrated in a study that assessed SSc patients without evidence of myocardial involvement and arrhythmias by rest and 24-h Holter ECG, echocardiography and radionuclide ventriculography, only to discover that 57% of patients suffered from supraventricular or ventricular tachyarrhythmia, sinus node dysfunction and atrioventricular conduction delay.
In SSc patients who had detailed cardiac physiological data available, 50% had normal findings on ECG and the most common ECG abnormality was isolated nonspecific ST-T wave changes (14%), and conduction abnormalities (17%). Furthermore, 10% had septal infarction pattern and 21% had ventricular conduction defects. The date resultant from this study suggested that septal infarction pattern or ventricular conduction abnormalities can point towards a more advanced myocardial involvement in patients with SSc.
Cardiac involvement in SSc results from multiple factors combined, such as microvascular alterations, collagen overproduction by altered fibroblasts with extracellular matrix deposition and complex immune system dysregulation.
SSc patients should routinely preform ECG as well as Doppler echocardiography, and if symptoms such as palpitations, syncope or dizziness are manifested, exercise testing, upright tilt-table testing and 24-h Holter monitoring should be the next option.
If physicians detect significant changes in the conduction and rhythm systems, cardiovascular risk factors should be assessed together with any symptoms of ischaemic heart disease. Moreover, if signs of SHD are visible, echocardiography by pulsed Doppler should be performed, alongside cardiac MRI to evaluate tissue damage.
SSc can involve multiple organs therefore the choice of treatment should be personalized depending on the patient. Different classes of anti-arrhythmics exist, however, corticosteroids, in particular methylprednisolone are associated with tachyarrhythmias, and some studies have correlated domperidone, a blocker of dopamine receptor, to serious ventricular arrhythmia or sudden cardiac death.
Implantable cardioverter defibrillators (ICDs) monitor the cardiac rhythm and have been effective in some patients to prevent malignant ventricular arrhythmias, nonetheless, it should only be considered for patients at high risk of sudden death, and in prevention for patients with a less than 30% LV ejection fraction with proven symptomatic ventricular tachyarrhythmia and without advanced organ failure other than the heart.
Catheter ablation therapy, a technique that destructs a selected atrial/ventricular zone, should be used as a first-line therapy in patients with recurrent re-entrant tachycardia or atrial flutter, or in patients with symptomatic, sustained, monomorphic ventricular tachycardia resistant or intolerant to pharmacological treatment.
Finally, pacemaker implantation should be preformed for complete heart block and other serious bradyarrhythmias.
Although arrhythmias and conduction defects can be mild, sometimes they can lead to death, proving to be important symptoms of cardiac involvement in patients with SSc. Although still a matter of debate, myocardial damage and fibrosis seem to be the most important factors, and an early detection of these conditions can prove to crucial in disease outcome for these patients.