Author(s): SCHEER, A., MAANIITTY, T., SARASTE, A., KNUUTI, J., HEINONEN, I., Institution: UNIVERSITY OF TURKU, Country: FINLAND, Abstract-ID: 1275

INTRODUCTION:
Sex differences in coronary artery atherosclerotic plaque composition and resting myocardial blood flow have been observed. Moreover, the relationship between coronary plaque burden and adverse cardiovascular events seems to be sex-dependent. In addition to imaging studies, exercise testing is commonly utilised in the assessment of coronary artery disease (CAD). We studied how coronary plaque burden and myocardial blood flow are associated with maximal workload capacity on exercise testing and how sex impacts these relationships.
METHODS:
Symptomatic outpatients with suspected obstructive CAD were prospectively enrolled at a tertiary hospital. All participants underwent coronary computed tomography angiography (CTA) to characterise atherosclerotic plaques, and positron emission tomography (PET) with 15O-water to assess myocardial blood flow (MBF) at rest and with intravenous adenosine vasodilation for the global myocardium, left anterior descending (LAD), left circumflex (LCx) and right coronary artery (RCA) territories. Participants additionally underwent clinical exercise stress testing on a cycle ergometer. Peak workload (last 4 minute average) and haemodynamic variables were reported from exercise testing. Spearman correlations by sex were used with and without partial adjustments to determine correlations.
RESULTS:
Among the 107 enrolled patients, the peak workload on exercise testing was recorded in 88 patients (55 males, 33 females). Global adenosine-induced MBF and myocardial flow reserve were positively correlated with peak workload in females (r=0.423, p=0.0159 and r=0.511, p=0.0028, respectively), and remained significant when adjusted for age, body mass index and coronary stenosis area percent (r=0.453, p=0.0156 and r=0.663, p=0.0001). The same pattern was seen for myocardial flow reserve for LAD, LCx and RCA territories in females. No associations between peak exercise workload and MBF were seen in the raw or adjusted correlations in males. Males had a significant negative association between peak exercise workload and CTA assessed percent diameter stenosis (r=-0.345, p=0.0106), which remained significant after adjustment for age and BMI (r=-0.381, p=0.0053). There were no associations between coronary artery stenosis severity and peak exercise workload observed in females.
CONCLUSION:
In patients with suspected CAD, higher peak exercise workload was associated with favourable myocardial blood flow indices in females and milder coronary artery stenosis severity in males. These findings suggest that the relationship between exercise tolerance and CAD phenotype is sex-dependent, and the results from clinical exercise testing in suspected CAD should be interpreted in the context of patient’s sex.