Worse Vascular Outcomes Found in Patients With Asthma

Patients with symptoms of asthma, regardless of physiological confirmation, experienced worse vascular outcomes and greater cardiovascular risk, which may be due to short-acting beta agonist (SABA) use, according to the results of a recent study.

Individuals with a clinical history of asthma had lower endothelial function than healthy controls, regardless of whether participants had physiological confirmation of the disease.

Study results, which were published in Respiratory Medicine, also showed that that participants with asthma who regularly used short-acting beta agonist (SABA) medications had increased arterial stiffness than those who did not use SABA.

Researchers aimed to compare markers of cardiovascular risk, specifically endothelial function, arterial stiffness, and systemic inflammation, among those with confirmed asthma, unconfirmed asthma, and healthy controls. Researchers also aimed to investigate the effect of SABA use on these vascular outcomes.

This cross-sectional study included 26 patients with confirmed asthma, 15 patients with unconfirmed asthma, and 26 healthy controls all recruited from the Edmonton, Canada metropolitan area. All participants in the study were aged between 18 to 45 years and current nonsmokers.

Participants completed a pulmonary function test and evaluation for asthma. Physiological evidence of asthma was defined as a clinical history of symptoms such as recurrent wheezing, cough, and/or chest tightness. Physiological evidence also includes a reversibility in forced expiratory volume in 1 second (FEV1) of ≥12% and 200mL, a ≥20% reduction in FEV1 after a methacholine challenge, or a ≥10% reduction in FEV1 after an exercise challenge.

Participants were labeled with confirmed asthma if they had a clinical history and physiological evidence of asthma. Those labelled with unconfirmed asthma had a clinical history but no physiological evidence of asthma. Healthy controls had no evidence of asthma. Researchers compared endothelial function, arterial stiffness, and systemic inflammation between these three groups of participants.

Researchers assessed participants’ endothelial function as flow-mediated dilation (FMD) after 5 minutes of supra-systolic forearm occlusion distal to the imaging site. A 1% decreased in FMD correlates with a 7% increase in cardiovascular risk.

Participants’ arterial stiffness was assessed using pulse wave velocity (PWV). PWV was measured between the carotid and radial artery. A 1 m/s increased in PWV corresponds to about a 16% increase in cardiovascular risk.

Systematic inflammation was assessed by C-reactive protein (CRP) levels in serum after venous blood was collected from the participants. CRP levels have been linked with cardiovascular risk, even for those without underlying cardiovascular morbidity.

Endothelial function was significantly lower in both confirmed and unconfirmed asthma groups than compared to healthy controls. There was no significant difference in FMD between the confirmed and unconfirmed asthma groups.

There was no significant difference found in arterial stiffness and systemic inflammation among both asthma groups and the controls.

Participants with bot confirmed and unconfirmed asthma were grouped together and then split based on SABA use. SABA was used by 19 participants and not used by 22 participants in the last year. There was no significant difference between in endothelial function and systemic inflammation between these two groups. However, SABA users had a significantly higher arterial stiffness by an average of 1.5 m/s than those not using SABA.

Limitations of this study include the small sample size and the inability to account for seasonal fluctuations in asthma symptoms due to the cross-sectional design. Also, this study did not adjust for other variables that can impact vascular outcomes.

Reduced vascular function was seen in participants with asthma regardless of physiological confirmation of asthma, suggesting that the link between asthma and cardiovascular risk may be due to factors other than asthma pathophysiology and perhaps due to asthma symptomatology, the researchers noted. The researchers also noted that this study highlights the need for proper asthma management to avoid inappropriate SABA use in patients with unconfirmed physiological asthma.

Reference

Henry SL, Moore LE, Brotto AR, Rowland S, Fuhr D, Stickland MK. Systemic vascular health is comprised in both confirmed and unconfirmed asthma. Respir Med. 2022;200. doi:10.1016/j.rmed.2022.106932