Cardiorespiratory fitness a key determinant of stroke

Cardiorespiratory fitness (CRF) is an independent determinant of stroke among asymptomatic men and women with no history of cardiovascular disease, new research shows. The role of biological determinants such as atrial fibrillation, and hypertension in stroke are well established yet little is known about the role of lifestyle factors such as physical inactivity. The data that does exist is mostly limited to studies in men and do not differential between fatal and non-fatal stroke, the researchers reported in Stroke. The current study examined the association between CRF and fatal and non-fatal stroke in a large cohort of men and women without known history of myocardial infarction (MI) or stroke. A total of 46,405 men and 15,282 women underwent a treadmill exercise test. Participants were then grouped into quartiles based on the maximal metabolic equivalents (METs) they achieved on the treadmill test. Cox regression models were used to assess and quantify the association between CRF and stroke outcomes (fatal, non-fatal and total strokes). Follow-up were over an average of 18 years in which time there were 863 strokes (241 fatal and 647 non-fatal). There was a significant inverse association between CRF and age-adjusted fatal, non-fatal, and total stroke rates for both men and women (p £ 0.05 for trend for each), and this relationship remained significant in men even after adjusting for cardiovascular risk factors (p £ 0.05 for trend). However, among women, while the relationship between CRF and non-fatal and total strokes remained significant (p £ 0.01 for trend for each), the relationship did not remain significant between CRF and fatal stroke (p £ 0.18 for trend). Furthermore, the researchers identified a CRF threshold of 7—8 METs to be associated with a substantially reduced rate of total stroke among both men and women. “Beyond this level of CRF, no further decreases in total stroke rate were noted for either men or women,” they added. “The present study demonstrated that higher CRF was significantly associated with lower rates of non-fatal and total stroke in women and in men and with lower rates of fatal stroke in men,” they said. The authors pointed out that the inclusion of extensive baseline examination to detect subclinical disease, the use of measured risk factors, a large number of person-years of follow-up, and the variety of stroke end points were key strengths in their study. However, their inability to adjust for diet or smoking habits and lack of examination of relationships between CRF and stroke subtype (haemorrhagic or ischaemic) were limitations. They concluded that the current study provides evidence that CRF is inversely associated with the incidence of total and non-fatal stroke in asymptomatic women and men and with fatal stroke in men. Reference Hooker, S. Sui, X. 2008, ‘Cardiorespiratory fitness as a predictor as a predictor of fatal and nonfatal stroke in asymptomatic women and men’ Stroke; 39: 2950—2957....