The effects of lockdown-induced air quality changes on the results of cardiac functional stress testing in coronary artery disease and heart failure patients

In vulnerable subjects, the increase in air pollution worsens the signs of myocardial ischemia. Lockdown during COVID-19 pandemics substantially cleaned the air. The objective of this is to assess the effects of air cleaning due to lockdown on stress echocardiography (SE) results. We enrolled 19 patients with chronic coronary artery disease and/or heart failure referred to SE (semi-supine bicycle exercise, n = 8, or dipyridamole, n = 11). Before and soon after lockdown, we assessed regional wall motion abnormalities (abnormal value: worsening of ≥ 2 segments), B-lines (a sign of pulmonary congestion, 4-site simplified scan, abnormal value ≥ 2), and coronary flow velocity reserve in left anterior descending artery (CFVR, abnormal value < 2.0). Local air quality indicators (same day of SE) of fine particulate matter (PM_2.5) and nitrogen dioxide (NO₂) were obtained from publicly available data sets of the regional authority of environmental protection. After lockdown, NO₂ concentration decreased from 19 ± 10 to 10 ± 4 μg/m³ (p = 0.006). After lockdown, abnormal responses remained unchanged for ischemia (21% vs 16%, p = ns) and decreased for B-lines (42% vs 5%, p = 0.008) and CFVR (84 vs 42%, p = 0.007). Changes in coronary flow velocity reserve (CFVR) were correlated to same-day variations in NO₂ (r = -0.578, p = 0.010) and preceding 30-day changes in PM_2.5 (r = -0.518, p = 0.023). After lockdown, air cleaning was associated with a beneficial effect on coronary small vessel dysfunction and alveolar-capillary barrier distress mirrored by improvement of CFVR and B-lines during SE in vulnerable patients. ClinicalTrials.gov Identifier: NCT 030.49995.