Electrocardiograms to Monitor Heart Health Advised for SSc-PH Patients

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by Forest Ray PhD |

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Changes from the norm in the electrical conduction of the heart — called cardiac axis deviations — are “common” and indicative of poorer outcomes in people with systemic sclerosis-related pulmonary hypertension (SSc-PH), a study reported.

Because cardiac axis deviations are easily measured by electrocardiography (ECG), monitoring for such deviations using this common, inexpensive, and non-invasive tool can help to guide patient care, its scientists suggested.

The study, “The Prognostic Value of Cardiac Axis Deviation in Systemic Sclerosis-related Pulmonary Hypertension,” was published in the journal Arthritis Care & Research.

The electrical cardiac axis describes the general direction of electrical conduction across the heart, which can deviate. Left axis deviation (LAD) and right axis deviation (RAD) can occur normally. But they can also associate with underlying medical disorders, such as pulmonary hypertension (PH).

Characterized by high blood pressure in the blood vessels that supply the lungs, PH is a leading cause of morbidity and mortality in SSc.

It remains unclear, however, whether electrical cardiac axis deviations indicate a poorer prognosis among patients with PH.

Researchers with Boston University School of Medicine reviewed ECGs from the Scleroderma Center of Research Translation database, looking at how cardiac axis deviations associated with mortality from a patient’s time of diagnosis, as well as other measures of cardiopulmonary health.

After excluding heart and/or lung transplant patients, they identified 169 SSc-PH patients with records of ECG readings and right heart catheterization, a standard means of assessing how well the heart is pumping.

“This present study is the largest cohort [group] to date investigating cardiac conduction system abnormalities, specifically cardiac axis deviation in patients with SSc-PH,” the investigators wrote.

RAD was evident in 28.4% of these people and LAD in 30.8%, while nine patients showed both LAD and RAD at different time points.

“We found that cardiac axis deviation is common in SSc-PH,” the researchers wrote.

Those with RAD had a greater frequency of diffuse cutaneous scleroderma, lower positive rate of autoantibodies (self-targeted antibodies that are a hallmark of scleroderma), and a lower degree of skin disease compared to patients with LAD and those with no evidence of right or left axis deviation.

RAD also associated with a higher use of pulmonary arterial hypertension (PAH)-specific therapies, specifically with a class of medications called prostacyclin analogs, compared with people in the other two group.

Five-year, all-cause mortality in people with SSc-PH was 41.8%. Male sex, poorer lung function, more severe PH — as assessed by the New York Heart Association functional classification — and treatment with PAH-specific medications all associated with all-cause mortality. (Researchers noted that 25 patients (14.8%) were lost to follow-up, and 22 (13%) did not have five years of follow-up.)

A greater risk of death was evident in people with either right or left axis deviation.

RAD, in particular, correlated with a nearly 10 times greater risk of mortality one year after PH diagnosis. While the occurrence of RAD more than a year following diagnosis also associated with a higher mortality risk, it was no longer statistically significant.

LAD also associated with a greater mortality risk, although generally less so than RAD.

Individuals exhibiting RAD also showed signs of right-sided cardiac disease, and more severe PH. LAD patients, while not associated with more severe PH, tended to show signs of left-sided cardiac disease, including left ventricle diastolic dysfunction (impaired contraction) and systolic dysfunction (impaired relaxation), as well as left ventricle dilation, a known complication of SSc.

“Taken together,” the researchers wrote, “these findings underline the importance of ECG in risk stratifying patients with SSc-PH. Given that it is widely available, inexpensive, and non-invasive, ECGs are a very feasible tool to help guide clinical care and decision-making in the care of these patients.”

Further work is planned “to determine whether cardiac axis deviation can predict PH among patients with SSc,” they added.