Obstructive Sleep Apnea Subtypes Linked to Cardiovascular Event Risks

Diego R. Mazzotti, PhD

Investigators have uncovered symptom subtypes for obstructive sleep apnea (OSA) that are both reproducible and associated with patient cardiovascular risks.

The findings from a 1200-plus OSA patient pool from the National Heart Lung & Blood Institute (NHLBI) Sleep Heart Health Study draw associations between 4 distinguished sleep apnea symptom subtypes and incident cardiovascular disease. Investigators now hope the findings aide tailored patient therapy.

A team of investigators—led by Diego R. Mazzotti, PhD, of the Division of Sleep Medicine, Department of Medicine at the University of Pennsylvania Perelman School of Medicine—sought to clearly define the cardiovascular-related consequences of previously OSA symptom subtypes.

Such subtypes, they observed, have been well-documented in both clinical and population samples—yet require further characterization.

Using the NHLBI-based study data, they assessed 1207 patients with OSA as per a apnea-hypopnea index of ≥ 15 events/h. The link between 4 subtypes and the prevalence of overall cardiovascular disease—as well its components of coronary heart disease, heart failure, and stroke—was assessed via logistic regression.

Mazzotti and colleagues also used Kaplan-Meier survival analysis as well as Cox proportional hazards models to evaluate the association between OSA subtypes and incident events.

They identified 4 symptom subtypes: disturbed sleep (12.6% of all patients); minimally symptomatic (32.6%); excessively sleepy (16.7%); and moderately sleepy (38.5%).

Though investigators found no significant associations with prevalent cardiovascular disease in adjusted models, they found the excessively sleepy symptom subtype was associated with a more than threefold greater risk of prevalent heart failure versus other subtypes.

Sleep apnea symptom subtype, in general were association with incident cardiovascular disease (P < .001), coronary heart disease (P= .015), and heart failure (P= .018). Again, excessively sleepy symptom subtype patients were at an increased risk (hazard ratio [HR], 1.7-2.4) versus the other 3 subtypes.

Mostly patients in the excessively sleep subtype showed significantly increased risk for prevalent and incident cardiovascular events when compared with individuals without obstructive sleep apnea.

In an interview with MD Magazine® at the American Thoracic Society (ATS) 2019 International Meeting this May, Neomi Shah, MD, MPH, detailed new clinical findings indicating an association between sleep apnea severity and patient risks for myocardial infarction, among other cardiovascular events.

Shah, the associate division chief of Pulmonary Critical Care & Sleep Medicine at Mount Sinai, told MD Mag it has been long established that sleep apnea itself is a risk factor for stroke, arrhythmias, cardiac death, and atrial fibrillation.

“But unfortunately, in the recent few years, the clinical trials in that we're trying to treat the sleep apnea condition with continuous positive airway pressure, therapy did not reduce the occurrence of some of these events,” Shah explained. “So it's a little puzzling, because we've shown that it is a risk factor for cardiovascular disease, but when we treated, it didn't really make the impact that we were hoping for it to make.”

On the treatment side, clinicians remain in a state of confusion as to how they can address these associated conditions, Shah noted. The awareness surrounding the link between OSA and cardiovascular disease is strong—resolutions to care are not.

Specifying patient risk based on symptom subtype may help physicians deliver more targeted therapy.

“OSA symptom subtypes are reproducible and associated with cardiovascular risk, providing important evidence of their clinical relevance,” Mazzotti and colleagues concluded.

The study, "Symptom Subtypes of Obstructive Sleep Apnea Predict Incidence of Cardiovascular Outcomes," was published online in ATS Journals.