Aims We aimed to investigate the association between the exercise systolic blood pressure (SBP) response and future hypertension (HTN) in normotensive individuals referred for cycle ergometry, with special regard to reference exercise SBP values and exercise capacity.Methods and results In this longitudinal cohort study, data from 14 428 exercise tests were cross-linked with Swedish national registries on diagnoses and medications. We excluded individuals with a baseline diagnosis of cardiovascular disease or HTN. The peak exercise SBP (SBPpeak) was recorded and compared with the upper limit of normal (ULN) derived from SBP(pea)k reference equations incorporating age, sex, resting SBP, and exercise capacity. To evaluate the impact of exercise capacity, three SBP to work rate slopes (SBP/W-slopes) were calculated, relative to either supine or seated SBP at rest or to the first exercise SBP. Adjusted hazard ratios [HRadjusted (95% confidence interval, CI)] for incident HTN during follow-up, in relation to SBP response metrics, were calculated. We included 3895 normotensive individuals (49 +/- 14 years, 45% females) with maximal cycle ergometer tests. During follow-up (median 7.5 years), 22% developed HTN. Higher SBP(peak )and SBPpeak > ULN were associated with incident HTN [HRadjusted 1.19 (1.14-1.23) per 10 mmHg, and 1.95 (1.54-2.47), respectively]. All three SBP/W-slopes were positively associated with incident HTN, particularly the SBP/W-slope calculated as supine-to-peak SBP [HRadjusted 1.25 (1.19-1.31) per 1 mmHg/10 W].Conclusion Both SBPpeak > ULN based on reference values and high SBP/W-slopes were associated with incident HTN in normotensive individuals and should be considered in the evaluation of the cycle ergometry SBP response.Lay summary We examined the systolic blood pressure (SBP) response during maximal bicycle exercise testing in individuals without hypertension (HTN) or established cardiovascular disease and found that:center dot When applying reference values for peak SBP during cycling exercise, accounting for age, sex, resting blood pressure (BP), and exercise capacity, exceeding the upper limit of normal was associated with twice as high relative risk of future HTN, compared with having a peak SBP within normal limits.center dot A steep increase in exercise SBP in relation to the increase in work rate was also associated with future HTN but did not always coincide with elevated peak SBP.

Objectives: This study aimed to evaluate the risk of all-cause mortality and incident cardiovascular disease associated with peak systolic blood pressure (PeakSBP) at clinical exercise testing.

Methods: Data from 10 096 clinical exercise tests (54% men, age 18-85 years) was cross-linked with outcome data from national registries. PeakSBP was compared with recently published reference percentiles as well as expressed as percentage predicted PeakSBP using reference equations.Natural cubic spline modelling and Cox regression were used to analyse data stratified by sex and baseline cardiovascular risk profile.

Results: Median [IQR] follow-up times were 7.9 [5.7] years (all-cause mortality) and 5.6 [5.9] years (incident cardiovascular disease), respectively. The adjusted risk of all-cause mortality [hazard ratio, 95% confidence interval (95% CI)] for individuals with PeakSBP below the 10th percentile was 2.00 (1.59-2.52) in men and 2.60 (1.97-3.44) in women, compared with individuals within the 10th--90th percentile. The corresponding risk for incident cardiovascular disease was 1.55 (1.28-1.89, men) and 1.34 (1.05-1.71, women). For males in the upper 90th percentile, compared with individuals within the 10th--90th percentile, the adjusted risks of all-cause death and incident cardiovascular disease were 0.35 (0.22-0.54) and 0.72 (0.57-0.92), respectively, while not statistically significant in women. Spline modelling revealed a continuous increase in risk with PeakSBP values less than 100% of predicted in both sexes, with no increase in risk more than 100% of predicted.

Conclusion: Low, but not high, PeakSBP was associated with an increased risk of mortality and future cardiovascular disease. Using reference standards for PeakSBP could facilitate clinical risk stratification across patients of varying sex, age and exercise capacity.

Background. Firefighting is one of the most physically demanding occupations and it requires a high cardiorespiratory fitness level.

Pre-duty medical evaluation of firefighters includes fitness testing and assessment of cardiac health to ensure that firefighters meet the minimum physical fitness standard and to ensure that they are not at increased risk of cardiac events. The medical evaluation methods for Swedish firefighters are regulated by the Swedish Work Environment Authority and include a 6 min constant workload treadmill (TM) test for fitness evaluation in which the firefighter wears full smoke diving equipment and a maximal effort exercise electrocardiography test (ExECG) at cycle ergometer (CE) for assessment of cardiac health. Previously, fitness was also evaluated by cycle ergometry.

The standard parameter for evaluation of ischaemic heart disease (IHD) is exercise-induced ST depression. In general, exercise testing of asymptomatic low-risk individuals is discouraged due to low sensitivity and specificity for IHD, generating both false-positive and false-negative test results. Heart rate (HR) adjustment of the ST-segment response has been shown to be superior to simple ST depression to evaluate cardiac ischaemia in some populations, but has not been extensively evaluated in an occupational setting.

Methods. We retrospectively analysed a cohort of 774 firefighters who were asymptomatic at the time of the testing.

In paper I, test approval, HR response, and calculated oxygen uptake from TM tests and CE tests for 424 firefighters (44±10 years) were compared.

Paper II methodologically described the process for data extraction, processing, and calculation of ExECG data from a clinical database. Procedures for noise assessment, error checking, and computerized calculation of ST/HR parameters were described.

In paper III, ExECG and medical records of 521 male firefighters (44±10 years) were studied. During 8.4 ± 2.1 years of follow-up, IHD was verified angiographically in 12 subjects. The predictive value of HR-adjusted ST variables (ST/HR index, ST/HR slope, and ST/HR loop) for IHD was evaluated.

In paper IV, subjects with objectively verified IHD were excluded and factors associated with exercise-induced nonischaemic ST depression were studied in the remaining 509 males (46±11 years).

Results. The firefighters had an average maximal exercise capacity of 281 ± 36 W (range 186-467 W) achieved by incremental CE exercise. To enable comparison, the maximal workload was converted to the workload sustainable for 6 min. It was more common to pass the 6 min TM fitness test but to fail the supposedly equivalent CE test rather than vice versa.

Twenty percent of the firefighters developed an ST depression of ≥o.1 mV in at least one lead during exercise and half of the firefighters had a horizontal or downsloping ST depression. While an abnormal ST response associated with an increased risk for IHD only in V4, both an abnormal ST/HR index and an abnormal ST/HR slope associated with IHD in three leads each. Clockwise rotation of the ST/HR loop was infrequent in all precordial leads (1%), but it associated with an increased risk for IHD.

In the subgroup without evidence of coronary artery disease, age and the HR response associated with ST depression, whereas hypertension, hyperlipidaemia, diabetes, blood pressure response, and exercise capacity did not.

Conclusions. Even though the calculated oxygen uptake was higher for the TM test than for the supposedly equivalent CE test, the higher treadmill approval rate may indicate that the fitness requirement for Swedish firefighters has been lowered by changing the test modality.

Exercise-induced ST depression was common in asymptomatic physically active men, although there were only a few cases of IHD during follow-up. If performing ExECG in asymptomatic, low-risk populations, ST/HR analysis could be given more importance. However, the limited clinical value of ExECG in low-risk populations was emphasised and needs to be reconsidered.

In asymptomatic, physically active men without coronary artery disease, false-positive ST depressions can be partially explained by HR variables rather than by common cardiovascular risk factors and blood pressure response to exercise.

Exercise electrocardiography (ExECG) is regularly performed by Swedish firefighters by law. Heart rate-corrected analysis of ST segment variables (ST/HR) has shown improved prediction of ischemic heart disease (IHD) compared to ST depression alone. This has not previously been extensively studied in asymptomatic persons with a low probability of IHD. We therefore evaluated the predictive performance of ST/HR analysis in firefighter ExECG. ExECG was studied in 521 male firefighters. During 8.4 ± 2.1 years, 2.3% (n = 12) were verified with IHD by catheterization or myocardial scintigraphy (age 51.5 ± 5.5 years) and were compared with firefighters without imaging proof of IHD (44.2 ± 10.1 years). The predictive value of ST depression, ST/HR index, ST/HR slope, and area and rotation of the ST/HR loop was calculated as age-adjusted odds ratios (OR), in 10 ECG leads. Predictive accuracy was analyzed with receiver operating characteristics (ROC) analysis. ST/HR index ≤-1.6 μV/bpm and ST/HR slope ≤-2.4 μV/bpm were associated with increased IHD risk in three individual leads (all OR > 1.0, P < 0.05). ST/HR loop area lower than the fifth percentile of non-IHD subjects indicated IHD risk in V4, V5, aVF, II, and -aVR (P < 0.05). ST depression ≤-0.1 mV was associated with IHD only in V4 (OR, 9.6, CI, 2.3-40.0). ROC analysis of each of these variables yielded areas under the curve of 0.72 or lower for all variables and leads. Clockwise-rotated ST/HR loops was associated with increased risk in most leads compared to counterclockwise rotation. The limited clinical value of ExECG in low-risk populations was emphasized, but if performed, ST/HR analysis should probably be given more importance.

Low adherence to recommended pre-participation cardiac evaluation of Swedish athletes Pre-participation cardiac evaluation of athletes is recommended by international organizations like the European Society of Cardiology and the American Heart Association, as well as by the Swedish Sports Confederation. The purpose of the evaluation is to prevent sudden cardiac death in athletes by early identification of individuals at risk. To our knowledge, no previous study has been made regarding the implementation of pre-participation cardiac evaluation of athletes in Sweden. We performed an electronical survey addressing sports clubs in one out of 21 districts in which the Swedish Sports Confederation is geographically divided. Only four out of 22 responding clubs with elite athletes preformed cardiac evaluation. Lack of knowledge about the recommendations as well as how to perform the evaluation were mentioned as reasons not to evaluate the athletes. Our results indicate the need for more information about pre-participation cardiac evaluation of athletes in Sweden.

The fitness of firefighters is regularly evaluated using exercise tests. We aimed to compare, with respect to age and body composition, two test modalities for the assessment work capacity. A total of 424 Swedish firefighters with cycle ergometer (CE) and treadmill (TM) tests available from Jan 2004 to Dec 2010 were included. We compared results from CE (6 min at 200 W, 250 W or incremental ramp exercise) with TM (6 min at 8° inclination, 4·5 km h(-1) or faster, wearing 24-kg protective equipment). Oxygen requirements were estimated by prediction equations. It was more common to pass the TM test and fail the supposedly equivalent CE test (20%), than vice versa (0·5%), P<0·001. Low age and tall stature were significant predictors of passing both CE and TM tests (P<0·05), while low body mass predicted accomplishment of TM test only (P = 0·006). Firefighters who passed the TM but failed the supposedly equivalent CE test within 12 months had significantly lower body mass, lower BMI, lower BSA and shorter stature than did those who passed both tests. Calculated oxygen uptake was higher in TM tests compared with corresponding CE tests (P<0·001). Body constitution affected approval differently depending on the test modality. A higher approval rate in TM testing suggests lower cardiorespiratory requirements compared with CE testing, even though estimated oxygen uptake was higher during TM testing. The relevance of our findings in relation to the occupational demands needs reconsidering.