Blood pressure response to exercise. A marker for future hypertension?

Beyond the new blood pressure guidelines: the beat goes on

The scope of hypertension (HTN) even for those involved in the field is staggering with numbers close to 60 million Americans and more than 1 billion individuals across the globe. It is the most common reason to seek medical attention and according to the World Health Organization, the number one cause of mortality in the world. Yet, we still don't know what is normal or abnormal. Even though the most recent 2017 Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults has created quite a commotion, new questions could be raised. The purpose of this Editorial not only to fuel more interest on this topic but also to create the notion that HTN needs to be considered a dynamic clinical entity rather than a static blood pressure reading.

Blood pressure response to exercise is exaggerated in normotensive diabetic patients

INTRODUCTION

The aim of this study was to investigate the blood pressure (BP) response to exercise in normotensive patients with type II diabetes mellitus (DM).

MATERIALS AND METHODS

A cross-sectional study was carried out on 75 normotensive subjects with type 2 DM (group 1), and 70 age-gender matched normotensive healthy volunteers (group 2). Treadmill exercise test, 24-h ambulatory BP monitoring (ABPM) were performed for each patients and healthy volunteers.

RESULTS

There were 67 patients (mean age 52 ± 9 years and 42% male) in group 1 and 68 healthy volunteers (mean age 51 ± 7 years and 43% male) in group 2. Eight patients from group 1 and 2 subjects from group 2 were excluded because of high BP on ABPM. Groups were similar for systolic BP (SBP) and diastolic BP (DBP) on office measurements and on ABPM. Groups were similar for rest SBP, DBP, heart rate, exercise duration on exercise test. Peak SBP was significantly higher in group 1 than in group 2, but peak DBP was not (196.9 ± 18 vs 165.9 ± 18.6 mmHg, p<0.001; 88.1 ± 11.6 vs 86.2 ± 8.7 mmHg, p = 0.283, respectively). Hypertensive response to exercise (HRE) was more frequent in group 1 than in group 2 [39 (58%) vs 6 (9%), p<0.001]. Independent predictors of peak SBP were DM, office SBP and male gender, while independent predictors of HRE were DM, office SBP and age in multivariate analysis.

CONCLUSIONS

SBP response to exercise is exaggerated in normotensive diabetic patients compared with non-diabetic subjects. DM, office SBP and male gender are independent predictors of peak SBP. DM, office SBP and age are independent predictors of HRE.

Usefulness of paradoxical systolic blood pressure increase after exercise as a predictor of cardiovascular mortality

Exercise treadmill testing (ETT) is a well-accepted examination for patients with suspected coronary artery disease (CAD), and exercise induced ST-segment deviation is commonly used for CAD detection. However, recent evidence shows that systolic blood pressure (SBP) changes during and after exercise were associated with CAD severity, risk of acute myocardial infarction and stroke, new-onset hypertension, and even cardiovascular mortality. We retrospectively assessed 3,054 patients referred for ETT in 1996. Blood pressure and heart rate were recorded at rest, during peak exercise, and 1 and 3 min after exercise. SBP at 3 min of recovery equal to or higher than that at 1-min of recovery was defined as paradoxical SBP increase. These patients were categorized into 4 groups according to ETT ST-segment change and postexercise SBP change. After 10 years of follow-up, 346 patients (11%) died, with 129 (4%) dying from cardiovascular disease (CVD). Among the 4 groups, patients with ischemic ST-segment change and paradoxical SBP increase were associated with a higher risk for mortality, with odds ratios of 1.86 (95% confidence interval 1.31 to 2.65) for all-cause mortality and 3.18 (95% confidence interval 1.94 to 5.20) for CVD mortality, respectively. Patients with isolated paradoxical SBP increase still had a higher risk of CVD mortality (odds ratio 1.80, 95% confidence interval 1.70 to 3.04), even after controlling other cardiovascular risk factors. In subgroup analysis of 346 mortality subjects, patients with ischemic ST-segment change and paradoxical SBP increase would be more likely to die from CVD. In conclusion, compared with ischemic ST-segment change, paradoxical SBP increase after exercise is an important and significant predictor of CVD mortality.

Cardiac Power During Exercise and the Risk of Stroke in Men

Background and Purpose— Low maximal oxygen uptake (VO 2max ) has been shown to predict the risk of stroke. However, VO 2max does not take into account the differences in cardiac afterload between subjects. The aim of this study was to examine the relationship of exercise cardiac power (ECP), defined as a ratio of VO 2max with peak systolic blood pressure (SBP) during exercise, with the risk for stroke.

Methods— Population-based cohort study with an average follow-up of 12 years from eastern Finland. A total of 1761 men with no history of stroke or coronary heart disease at baseline participated. Among these men, 91 strokes occurred, of which 69 were attributable to ischemic causes.

Results— The relative risk of any stroke in men with low ECP (<10.3 mL/mm Hg) was 2.7 (95% CI, 1.2 to 6.0; P =0.01; P =0.02 for the trend across the quartiles), and the relative risk for ischemic stroke was 2.7 (95% CI, 1.1 to 7.0; P =0.03; P =0.04 for trend across the quartiles) compared with men having high ECP (>14.3 mL/mm Hg) during exercise after adjusting for age, examination year, cigarette smoking, alcohol consumption, body mass index, diabetes, serum total cholesterol level, energy expenditure of physical activity, exercise-induced myocardial ischemia, and the use of antihypertensive medication. After further adjustment for resting SBP, results were statistically nonsignificant.

Conclusions— Low ECP provides noninvasive and easily available measure for stroke risk. One of the most potential explanations for the association between ECP and the increased risk of stroke is an elevated afterload and peripheral resistance indicated by elevated SBP.

Systolic Blood Pressure During Recovery From Exercise and the Risk of Acute Myocardial Infarction in Middle-Aged Men

We prospectively assessed the association of systolic blood pressure (SBP) after exercise with the risk of an acute myocardial infarction. Limited information exists currently on the role of SBP during recovery period with the risk of acute myocardial infarction. SBP was measured every 2 minutes during and after a progressive cycle ergometer exercise test in a representative sample of 2336 men (aged 42 to 61 years). During an average follow-up period of 13.1 years, 358 acute myocardial infarctions occurred. An incremental rise of 10 mm Hg per minute in SBP at 2 minutes after exercise (relative risk, 1.07-fold; 95% confidence interval [CI], 1.03 to 1.12; P=0.001) was associated with the risk of acute myocardial infarction after adjustment for age, alcohol consumption, smoking, serum lipids, diabetes mellitus, body mass index, resting SBP, regular use of antihypertensive medications, physical fitness, heart rate, and ischemic ECG findings during exercise. Men with elevated SBP of >195 mm Hg after exercise had a 1.69-fold (95% CI, 1.24 to 2.30; P=0.001) risk for an acute myocardial infarction compared with those with SBP <170 mm Hg after adjustment for age, other risk factors, and resting SBP. SBP after exercise provides an incremental predictive value for acute myocardial infarction beyond that of resting SBP. This emphasizes the importance of SBP measurements after the exercise test because it provides additional valuable prognostic measure with regard to acute myocardial infarction.

Capillary rarefaction and abnormal cardiovascular reactivity in hypertension

OBJECTIVE

To determine the effects of capillary rarefaction on cardiovascular reactivity and microcirculatory functioning in essential hypertension.

DESIGN

Hypertension is associated with abnormal cardiovascular reactivity and increased vasoconstriction. Capillary rarefaction amplifies these abnormalities, which modify microcirculatory hemodynamics. Hence this study of the hemorheological pattern and the veno-arteriolar reflex in hypertensive patients and normotensive control subjects.

METHODS

Sixty-one men with never-treated essential hypertension and capillary rarefaction (< 80 capillaries per field) and 20 age-matched and sex-matched controls underwent a strenuous cycle ergometer test to monitor, during exercise and recovery, the blood pressure profile and the hemorheological pattern: blood viscosity at low shear, hematocrit and leukocyte counts, soluble P-selectin levels, and red and white blood cell filterability rates. The veno-arteriolar reflex was determined by laser-Doppler flowmetry before exercise and at recovery.RESULTS Hypertensive men with < or = 72 capillaries per field had an abnormal hemorheological profile before exercise. The physiological response to exercise was observed only in the controls and in hypertensives with > or = 73 capillaries per field. Abnormal responses to exercise worsened as capillaries were more rarefied. At recovery, hemorheological parameters in hypertensives with 65-72 capillaries per field returned to baseline, remaining significantly (P < 0.05) different to control values. Variations in the hemorheological pattern in hypertensives with < 64 capillary per field persisted at recovery. The veno-arteriolar reflex followed the same pattern.

CONCLUSION

A reduced microvascular network may contribute to abnormal cardiovascular reactivity and to exercise-induced rheological abnormalities in hypertension.

Blood pressure response to heart rate during exercise test and risk of future hypertension

Previous works have shown that exaggerated blood pressure response to exercise is a valid risk marker for future hypertension, yet the use of an exercise test as a means of early prediction of hypertension still requires methodological development and confirmation. The purpose of this study was to determine abnormal ranges of blood pressure responses in relation to heart rate increase during exercise and to examine the clinical utility of exercise blood pressure measurement in evaluating individual risk for developing hypertension. We examined exercise test data from a population-based sample of 1033 nonmedicated normotensive men (mean age, 42.9+/-8.5 years; range, 20 to 59 years). Percentile curves of systolic and diastolic blood pressure responses to relative heart rate increments during submaximal exercise were constructed using a third-order polynomial model with multiple regression analysis. Of the original study sample, a cohort of 726 subjects was followed for hypertensive outcome for an average period of 4.7 years. Progression to hypertension, defined as a blood pressure of > or =140/90 mm Hg or the initiation of antihypertensive therapy, was found in 114 subjects (15.4%). Kaplan-Meier survival estimates showed that the cumulative incidence of hypertension increased progressively with higher percentiles of systolic and diastolic blood pressure response (both, P<0.01). A Cox proportional survival analysis revealed a significantly increased risk for developing hypertension associated with exaggerated blood pressure response to exercise after multivariable adjustments for traditional risk factors (relative risk, 3.8; 95% confidence interval, 2.3 to 6.1). These results suggest that an exaggerated blood pressure response to heart rate during exercise is predictive of future hypertension independent of other important risk factors and lend further support to the concept that blood pressure measurement during exercise test is a valuable means of identifying normotensive individuals at high risk for developing hypertension.

Systolic blood pressure response to exercise stress test and risk of stroke

BACKGROUND AND PURPOSE

Systolic blood pressure (SBP) during exercise has been found to predict a future diagnosis of hypertension, coronary heart disease, and cardiovascular disease death. No studies have been conducted to show a relationship between SBP during exercise test and stroke. The aim of the present study was to study the associations between SBP rise, percent maximum SBP at 2 minutes after exercise, and the risk of stroke in a population-based sample of men with no prior coronary heart disease.

METHODS

SBP was measured every 2 minutes during and after the exercise test. The subjects were a population-based sample of 1026 men without clinical coronary heart disease, antihypertensive medication, or prior stroke at baseline. During an average follow-up of 10.4 years, there were 46 cases of stroke (38 ischemic strokes).

RESULTS

Men with SBP rise >19.7 mm Hg per minute of exercise duration had a 2.3-fold increased risk of any stroke and a 2.3-fold increased risk of ischemic stroke compared with men whose SBP rise was <16.1 mm Hg/min. Similarly, percent maximum SBP at 2 minutes after exercise (SBP at 2 minutes' recovery divided by maximum SBP) was associated (highest tertile) with a 4.6-fold increased risk of any stroke and a 5.2-fold increased risk of ischemic stroke.

CONCLUSIONS

SBP rise during exercise and percent maximum SBP at 2 minutes after exercise were directly and independently associated with the risk of all stroke and ischemic stroke. Exercise SBP testing may be recommended as an additional tool in the prediction of future stroke.

Exercise BP response in subjects with high-normal BP: exaggerated blood pressure response to exercise and risk of future hypertension in subjects with high-normal blood pressure

OBJECTIVES

This study was designed to assess the clinical usefulness of an exaggerated blood pressure (BP) response to exercise (EBPR) in predicting the development of hypertension from a high-normal state.

BACKGROUND

Exaggerated BP response during both dynamic and isometric exercises are associated with increased risk of future hypertension, while the significance of these responses concerning the identification of individuals with high-normal BP who are prone to develop hypertension is unknown.

METHODS

The study population comprised a sample of 239 men with high-normal BP (aged 42.3 +/- 5.9 years) who underwent a symptom-limited bicycle ergometer exercise testing at baseline and then were followed for 5.1 years.

RESULTS

The Kaplan-Meier survival analysis showed that the subjects in the upper quartile of BP response to exercise had a significantly higher cumulative incidence of hypertension on follow-up than those in the middle two and lower quartiles (log-rank test, p < 0.05). Multivariate analysis using the Cox proportional hazards survival model showed that the EBPR was significantly and independently associated with the risk of developing hypertension after adjustment for some traditional risk factors for hypertension (RR = 2.31, 95% confidence interval = 1.45 to 6.25).

CONCLUSIONS

These findings suggest that an EBPR is an important risk factor for new-onset hypertension from a high-normal state and, thus, exercise testing can provide valid information that may help identify individuals with high-normal BP at a greater risk of future hypertension.

Blood pressure response during treadmill testing as a risk factor for new-onset hypertension. The Framingham heart study

BACKGROUND

Although systolic blood pressure (SBP) response to exercise has been shown to predict subsequent hypertension in small samples of men, this association has not been studied in a large population-based sample of middle-aged men and women. The purpose of this study was to examine, in normotensive subjects, the relations of SBP and diastolic blood pressure (DBP) during the exercise and recovery periods of a graded treadmill test to the risk of developing new-onset hypertension.

METHODS AND RESULTS

BP data from exercise testing in 1026 men and 1284 women (mean age, 42+/-10 years; range, 20 to 69 years) from the Framingham Offspring Study who were normotensive at baseline were related to the incidence of hypertension 8 years later. New-onset hypertension, defined as an SBP >/=140 mm Hg or DBP >/=90 mm Hg or the initiation of antihypertensive drug treatment, occurred in 228 men (22%) and 207 women (16%). Exaggerated SBP (Ex-SBP 2) and DBP (Ex-DBP 2) response and delayed recovery of SBP (R-SBP 3) and DBP (R-DBP 3) were defined as an age-adjusted BP greater than the 95th percentile during the second stage of exercise and third minute of recovery, respectively. After multivariable adjustment, Ex-DBP 2 was highly predictive of incident hypertension in both men (OR, 4.16; 95% CI, 2.15, 8.05) and women (OR, 2.17; CI, 1.19, 3.96). R-SBP 3 was predictive of hypertension in men in a multivariable model that included exercise duration and peak exercise BP (OR, 1.92; CI, 1.00, 3.69). Baseline resting SBP (chi2, 23.4 in men and 34.7 in women) and DBP (chi2, 11.3 in men and 13.1 in women) had stronger associations with new-onset hypertension than exercise DBP (chi2, 16.4 in men and 6.1 in women) and recovery SBP (chi2, 6.5 in men and 2.1 in women) responses.

CONCLUSIONS

An exaggerated DBP response to exercise was predictive of risk for new-onset hypertension in normotensive men and women. An elevated recovery SBP was predictive of hypertension in men. These findings may reflect subtle pathophysiological features in the preclinical stage of hypertension.

Blood pressure level and variability in the prediction of blood pressure after 5-year follow-up

We compared mean intra-arterial ambulatory blood pressure (IAMB), blood pressure (BP) diurnal profiles are variability, and postural measurements with casual sphygmomanometric measurements for the prediction of future BP. We studied 97 healthy, ummedicated men classified as normotensive (NT, n = 34), borderline hypertensive (BHT, n = 29), or mildly hypertensive (HT, n = 34) by repeated casual measurements during the 2 months before IAMB. Five years later, we reassessed 79 subjects (81%) using casual BP measurements and noninvasive ambulatory 24-hour BP monitoring (NAMB). IAMB level generally correlated well with follow-up BP and slightly better with NAMB level than with casual measurements (24-hour IAMB versus follow-up NAMB systolic BP [SBP], r = .64, P < .001; versus diastolic' BP [DBP], r = .52, P < .001). NT and BHT subgroup correlations were of similar strength, but the relationship in the HT subgroup was not significant. Similarly, when we examined daytime and nighttime BP levels, nighttime BP correlated better with follow-up BP in NT and BHT but not in HT. The only measures that were significantly related to follow-up BP in HT were two BP variability measures, SD and the range of variability (RV80: 90th minus 10th percentile), (initial 24-hour IAMB SD and follow-up BP, r = .42 to r = .52, P < .05 to P < .01; RV80 versus follow-up BP, r = .43 to r = .52, P < .05 to P < .01). Correlations of follow-up BP with postural BP were generally weaker than with casual BP or IAMB level. Linear stepwise regressions for SBP and DBP separately (including all IAMB variables) demonstrated that the best single predictor for follow-up BP was 24-hour IAMB SBP level, which explained 41% of follow-up NAMB SBP level variance (F = 52.6, P < .001). However, in a second analysis including casual values, casual SBP alone explained 44% of follow-up NAMB SBP variance (F = 62.5, P < .001), whereas IAMB SBP added only 4% (F = 5.5, P < .05). Predictions of follow-up DBP were always poorer. After 5 years, 70% of NT and 86% of HT were still in their initial classification group, but 67% of BHT had become hypertensive. In these new HT (n = 16), initial IAMB level correlated most strongly with follow-up NAMB level (24-hour SBP, r = .70, P < .01; 24-hour DBP, r = .55, P < .05). The only other significant demographic variable predicting future BP was change in weight over 5 years, which added 10% to the explanation of future casual SBP variance (F = 12.5, P = .0007) and 15% to casual DBP variance (F = 18.0, P = .0001); for NAMB, the percentages were lower. In logistic regression, those NT and BHT who became hypertensive (n = 22) had a 75% probability of becoming hypertensive if they gained 11.7 kg or more during 5 years (X2 = 4.5, P = .03). To conclude, BP tended to increase in all groups, especially in BHT, during follow-up. Nominal differences were observed between casual measurements and BP level measures in the prediction of future BP, and their explanatory value for future BP was generally less than 50%. However, for BHT who became hypertensive, BP level and variability measurements somewhat improved the prediction of follow-up BP. Weight gain was an important additional predictor for future hypertension in both NT and BHT.

Genetic regulation of hemodynamic variables during dynamic exercise. The MCV twin study

BACKGROUND

Both resting and exercise levels of blood pressure in individuals have been used as predictors of adult hypertension. One possible mechanism underlying the relation between childhood resting and exercise blood pressure and future blood pressure is a set of genes expressed in childhood that persists to regulate adult blood pressure.

METHODS AND RESULTS

To investigate the genetic relation of blood pressure and heart rate during both rest and exercise, we asked: (1) Are the genes that regulate resting hemodynamic variables the same genes that regulate these variables during exercise? (2) How much of the variance in exercise hemodynamic variables is genetic and how much is environmental? (3) Do the genetic and environmental influences on hemodynamic responses change with increasing levels of exercise? To determine how genetic and environmental effects expressed at rest influenced responses during dynamic exercise, a genetic analysis was conducted by fitting a series of models to the covariance matrices with the use of the LISREL VII program.

CONCLUSIONS

We found that all the genetic effects expressed at the later stages of exercise can be explained by genetic effects expressed at rest and at the first stage of exercise. The environmental effects appear to be workload specific and include errors of measurement.

Blood pressure responses to a progressive step test in normotensive males and females

This study documents the blood pressure responses to a progressive step test adapted from the Canadian Aerobic Fitness Test (CAFT). Subjects were administered the first five stages of the CAFT in a progressive and discontinuous manner. Mean heart rate, SBP, and delta SBP increased linearly with exercise intensity, while mean diastolic blood pressure remained stable. The variables that contributed most to delta SBP (Stage 3) in males were age and degree of participation in physical activity, and in females the variables were body weight and degree of participation. Criteria for the detection of an exaggerated (mean delta SBP + 1 SD) and highly exaggerated (mean delta SBP + 2 SD) SBP response were defined. Resting normotensive individuals who demonstrate an excessive exercise blood pressure response seem to do so at the lowest levels of stepping intensities. This step test protocol appears to be a useful and practical procedure for assessing the exercise blood pressure response in higher risk individuals.