Avaliação da rigidez arterial em asmáticos moderados e graves de distintos fenótipos

Abstract

Bronchial asthma is a chronic inflammatory disease of the airways affecting all age groups. Worldwide, it represents a relevant impact on health care systems. It is considered a heterogeneous disease, with different phenotypes or endotypes established according to clinical, functional or pathophysiological characteristics, which confer variable degrees of bronchial hyperresponsiveness. It is assumed that the inflammatory process of asthma is not restricted to the airways. Therefore, a systemic inflammatory component may be related to the greater risk of other comorbidities, such as cardiovascular diseases. A marker closely related to this risk is the degree of arterial stiffness, which can be measured non-invasively using equipment that determines the pulse wave velocity (PWV) in the arteries. The objective of the present cross-sectional study is to evaluate the degree of arterial stiffness in moderate to severe adult asthmatic patients, considering different phenotypes, according to clinical, functional and inflammatory features. Such characteristics include disease severity and degree of clinical control, the moment of diagnosis confirmation and elapsed time since then, functional ventilatory parameters linked to obstructive disorders, and inflammation biomarkers such as the fraction of nitric oxide in exhaled gas (FeNO) and blood levels of eosinophils and ultrasensitive C-reactive protein (US-CRP). Thirty asthmatic patients and nine healthy controls, between 18 and 54 years old, took part in the study. After a clinical interview, they underwent spirometry, plethysmography, carbon monoxide diffusing capacity, nitrogen washout test, measurement of the exhaled fraction of nitric oxide, assessment of PWV, in addition to blood collection to measure inflammatory biomarkers. For each clinical, functional or inflammatory variable, asthmatics were divided into two subgroups, according to the median, in most cases. The results revealed that patients with a greater degree of bronchial obstruction, air trapping and heterogeneity in ventilation distribution demonstrated higher PWV values compared to controls. The average PWV in the subgroup of asthmatics with FEV1/FVC ratio <70% was 6.83±0.81m/s (vs 5.49±0.68m/s in controls, p=0.001), in the subgroup with VEF1<76% was 6,69±1,01m/s (p=0,01 vs controls), in the subgroup with RV/TLC ≥33 was 6.62±0.95m/s (p=0.018 vs control group) while in the subgroup with the highest phase III slope values in nitrogen washout test it was 6.63±0.98m/s (p= 0.033 vs controls). When adjusted for age, statistical significance was maintained in all cases. Likewise, from a clinical point of view, more severe patients with late-onset asthma (diagnosis after 12 years of age) had higher PWV values than controls (respectively 6.61±1.06 and 6.72±1.16m/s vs 5.49 ±0.68m/s, p=0.013 and p=0.026), maintaining statistical significance after correction for age (respectively, p=0.037 and p=0.030). When considering the subgroups constructed according to the values of the inflammatory variables (FeNO, US-CRP and eosinophils), there were no statistical differences in PWV between asthmatics and controls. The findings therefore indicate a greater degree of arterial stiffness in patients with the most severe clinical forms of the disease and with worse obstructive ventilatory dysfunction, suggesting the need for further investigations with an expansion of the population sample.