Resting blood pressure is one of the major risk factors for stroke. Our group recently showed that maximal blood pressure during exercise testing is a strong predictor of stroke in this cohort, independently of resting blood pressure. In the present study we investigate if maximal systolic blood pressure's ability to predict stroke is influenced by a person's level of cardiorespiratory fitness.
The study enrolled 2014 healthy men aged 40–59 years between 1972–1975. The baseline examination included a maximal exercise test and the men were followed for a total of 35 years. Data on first-time stroke were collected from follow-up visits, hospital medical records from all national hospitals, and the national Cause of Death Registry. For data analyses, we grouped the men according to high or low fitness level (above/below median, values adjusted for age) and further for quartiles of maximal blood pressure. Multi-adjusted Cox regression analyses (including adjustment for resting blood pressure) were used to estimate risks for stroke.
During a median follow-up of time 31.9 years 316 first-time strokes occurred. There were no losses to follow-up. Fitness levels correlated positively with maximal systolic blood pressure. Among men with high fitness level, the highest quartile of maximal blood pressure had a higher risk of stroke than the lowest quartile (hazard ratio 1.75, confidence interval 1.06–2.94, p = 0.03). Among men with low fitness level, the highest quartile of maximal systolic blood pressure had a non-significantly higher risk of stroke than the lowest quartile (hazard ratio 1.50, confidence interval 0.91–2.63, p = 0.11). When resting systolic blood pressure was omitted from the models, maximal systolic blood pressure predicted stroke significantly in both fit and unfit men.
In healthy middle-aged men, maximal systolic blood pressure predicted stroke in men with high cardiorespiratory fitness, independently of resting systolic blood pressure. In men with low cardiorespiratory fitness the association was not significant, but there was no evidence of a qualitative different effect in this subgroup, and further research is needed to assess if maximal blood pressure has a predictive value for stroke in men, independently of fitness levels.
1University of Oslo, Faculty of Medicine, Oslo, Norway
2Oslo University Hospital Ullevål, Department of Cardiology, Oslo, Norway