Invasive aortic pulse pressure is not superior to cuff pulse pressure in cardiovascular risk prediction.

OBJECTIVE: Aortic pulse pressure (PP) represents the hemodynamic cardiac and cerebral burden more directly than cuff PP. The objective of this study was to investigate whether invasively measured aortic PP confers additional prognostic value beyond cuff PP for cardiovascular events and death. With increasing age, cuff PP progressively underestimates aortic PP. Whether the prognostic association between cuff PP and outcomes is age-dependent remains to be elucidated. METHODS: Cuff PP and invasively measured aortic PP were recorded in 21 908 patients (mean age 63 years, 58% men, 14% with diabetes) with stable angina pectoris undergoing elective coronary angiography during January 2001--December 2012. Multivariate Cox models were used to assess the association with incident myocardial infarction, stroke, and death. Discrimination was assessed using Harrell's C-index. RESULTS: During a median follow-up period of 3.7 years (range 0.1-10.8 years), 422 strokes, 511 myocardial infarctions, and 1530 deaths occurred. Both cuff and aortic PP were associated with stroke, myocardial infarction, and death in crude analyses. However, only cuff PP remained associated with stroke (hazard ratio per 10 mmHg, 1.06 (95% confidence interval (CI) 1.01--1.12)] and myocardial infarction [hazard ratio per 10 mmHg 1.05 (95% CI 1.01--1.11)] in multivariate Cox models. Both cuff and aortic PP lost significance as predictors of death in multivariate models. Age did not modify the prognostic association between cuff PP and stroke, myocardial infarction, and death. CONCLUSION: Invasively measured aortic PP did not add prognostic information about cardiovascular outcomes and death beyond cuff PP in patients with stable angina pectoris.

Influence of Age on Upper Arm Cuff Blood Pressure Measurement.

Blood pressure (BP) is a leading global risk factor. Increasing age is related to changes in cardiovascular physiology that could influence cuff BP measurement, but this has never been examined systematically and was the aim of this study. Cuff BP was compared with invasive aortic BP across decades of age (from 40 to 89 years) using individual-level data from 31 studies (1674 patients undergoing coronary angiography) and 22 different cuff BP devices (19 oscillometric, 1 automated auscultation, 2 mercury sphygmomanometry) from the Invasive Blood Pressure Consortium. Subjects were aged 64±11 years, and 32% female. Cuff systolic BP overestimated invasive aortic systolic BP in those aged 40 to 49 years, but with each older decade of age, there was a progressive shift toward increasing underestimation of aortic systolic BP (P<0.0001). Conversely, cuff diastolic BP overestimated invasive aortic diastolic BP, and this progressively increased with increasing age (P<0.0001). Thus, there was a progressive increase in cuff pulse pressure underestimation of invasive aortic PP with increasing decades of age (P<0.0001). These age-related trends were observed across all categories of BP control. We conclude that cuff BP as an estimate of aortic BP was substantially influenced by increasing age, thus potentially exposing older people to greater chance for misdiagnosis of the true risk related to BP.

Accuracy of Cuff-Measured Blood Pressure: Systematic Reviews and Meta-Analyses.

BACKGROUND: Hypertension (HTN) is the single greatest cardiovascular risk factor worldwide. HTN management is usually guided by brachial cuff blood pressure (BP), but questions have been raised regarding accuracy. OBJECTIVES: This comprehensive analysis determined the accuracy of cuff BP and the consequent effect on BP classification compared with intra-arterial BP reference standards. METHODS: Three individual participant data meta-analyses were conducted among studies (from the 1950s to 2016) that measured intra-arterial aortic BP, intra-arterial brachial BP, and cuff BP. RESULTS: A total of 74 studies with 3,073 participants were included. Intra-arterial brachial systolic blood pressure (SBP) was higher than aortic values (8.0 mm Hg; 95% confidence interval [CI]: 5.9 to 10.1 mm Hg; p < 0.0001) and intra-arterial brachial diastolic BP was lower than aortic values (-1.0 mm Hg; 95% CI: -2.0 to -0.1 mm Hg; p = 0.038). Cuff BP underestimated intra-arterial brachial SBP (-5.7 mm Hg; 95% CI: -8.0 to -3.5 mm Hg; p < 0.0001) but overestimated intra-arterial diastolic BP (5.5 mm Hg; 95% CI: 3.5 to 7.5 mm Hg; p < 0.0001). Cuff and intra-arterial aortic SBP showed a small mean difference (0.3 mm Hg; 95% CI: -1.5 to 2.1 mm Hg; p = 0.77) but poor agreement (mean absolute difference 8.0 mm Hg; 95% CI: 7.1 to 8.9 mm Hg). Concordance between BP classification using the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure cuff BP (normal, pre-HTN, and HTN stages 1 and 2) compared with intra-arterial brachial BP was 60%, 50%, 53%, and 80%, and using intra-arterial aortic BP was 79%, 57%, 52%, and 76%, respectively. Using revised intra-arterial thresholds based on cuff BP percentile rank, concordance between BP classification using cuff BP compared with intra-arterial brachial BP was 71%, 66%, 52%, and 76%, and using intra-arterial aortic BP was 74%, 61%, 56%, and 65%, respectively. CONCLUSIONS: Cuff BP has variable accuracy for measuring either brachial or aortic intra-arterial BP, and this adversely influences correct BP classification. These findings indicate that stronger accuracy standards for BP devices may improve cardiovascular risk management.

Evaluation of interarm blood pressure differences using the Microlife WatchBP Office in a clinical setting.

OBJECTIVE: The aim of this study was to evaluate the usefulness of Microlife WatchBP Office and the effect of increasing the number of measurements in the clinical evaluation of systolic interarm difference (IAD). PATIENTS AND METHODS: Office blood pressure was measured simultaneously on both arms in 339 patients (85% diabetic) using the Microlife WatchBP Office, a fully automatic, oscillometric device. The patients included were all scheduled for ambulatory blood pressure measurement at the outpatient clinic of endocrinology at Silkeborg Regional Hospital, Denmark. Two successive sets of three individual measurements were made. A statistical analysis of variance was carried out on the measurements. RESULTS: In the first set of measurements, the mean IAD was -0.3 mmHg and the prevalence of IAD greater than or equal to 10 mmHg was 9.1%. Only 7.6% of the patients with an IAD less than 10 mmHg in the first set of measurements had an IAD greater than or equal to 10 mmHg in the second set of measurements. The 95% limits of agreement for the mean IAD for a single set of three measurements were ±13.16 mmHg. The probability of detecting an IAD more than 10 mmHg only increased slightly with an increasing number of measurements. CONCLUSION: A single set of triplicate measurements using Microlife WatchBP is an acceptable method for evaluating IAD as more measurements do little to improve the probability of detecting an IAD more than 10 mmHg because of high intraindividual variation.

Invasively Measured Aortic Systolic Blood Pressure and Office Systolic Blood Pressure in Cardiovascular Risk Assessment: A Prospective Cohort Study.

Aortic systolic blood pressure (BP) represents the hemodynamic cardiac and cerebral burden more directly than office systolic BP. Whether invasively measured aortic systolic BP confers additional prognostic value beyond office BP remains debated. In this study, office systolic BP and invasively measured aortic systolic BP were recorded in 21 908 patients (mean age: 63 years; 58% men; 14% with diabetes mellitus) with stable angina pectoris undergoing elective coronary angiography during January 2001 to December 2012. Multivariate Cox models were used to assess the association with incident myocardial infarction, stroke, and death. Discrimination and reclassification were assessed using Harrell's C and the Continuous Net Reclassification Index. Data were analyzed with and without stratification by diabetes mellitus status. During a median follow-up period of 3.7 years (range: 0.1-10.8 years), 422 strokes, 511 myocardial infarctions, and 1530 deaths occurred. Both office and aortic systolic BP were associated with stroke in patients with diabetes mellitus (hazard ratio per 10 mm Hg, 1.18 [95% confidence interval, 1.07-1.30] and 1.14 [95% confidence interval, 1.05-1.24], respectively) and with myocardial infarction in patients without diabetes mellitus (hazard ratio, 1.07 [95% confidence interval, 1.02-1.12] and 1.05 [95% confidence interval, 1.01-1.10], respectively). In models including both BP measurements, aortic BP lost statistical significance and aortic BP did not confer improvement in either C-statistics or net reclassification analysis. In conclusion, invasively measured aortic systolic BP does not add prognostic information about cardiovascular outcomes and all-cause mortality compared with office BP in patients with stable angina pectoris, either with or without diabetes mellitus.

Assessment of central blood pressure in patients with type 2 diabetes: a comparison between SphygmoCor and invasively measured values.

BACKGROUND: The SphygmoCor is used for noninvasive assessment of ascending aortic blood pressure (BP). However, the validity of the SphygmoCor transfer function has not been tested in an exclusively type 2 diabetic patient sample. Calibration with systolic (SBP) and diastolic (DBP) brachial BP has previously been associated with substantial imprecision of central BP estimates. We hypothesized that different noninvasive calibration strategies might improve the accuracy of the estimated ascending aortic BPs. METHODS: In 34 patients with type 2 diabetes we estimated ascending aortic SBP and DBP using the SphygmoCor device and compared these data with invasively recorded data. The validity of the transfer function was assessed by calibrating with invasively recorded DBP and mean BP (MBP). The influence of noninvasive calibration strategies was assessed by calibrating with brachial oscillometric SBP+DBP vs. DBP+MBP using a form factor (ff) of 0.33 and 0.40, respectively. RESULTS: When calibrating with invasive BP, the difference between estimated and invasively measured ascending aortic SBP and DBP was -2.3±5.6/1.0±0.9 mm Hg. When calibrating with oscillometric brachial BPs, the differences were -9.6±8.1/14.1±6.2 mm Hg (calibration with SBP and DBP), -8.3±11.7/13.9±6.1 mm Hg (DBP and MBP; ff = 0.33), and 1.9±12.2/14.1±6.2 mm Hg (DBP and MBP; ff = 0.40), respectively. Calibration with the average of 3 brachial BPs did not improve accuracy. CONCLUSIONS: The SphygmoCor transfer function seems valid in patients with type 2 diabetes. Noninvasive calibration with DBP and MBP (ff = 0.40) enables accurate estimation of mean ascending aortic SBP at the group level. However, the wide limits of agreement indicate limited accuracy in the individual patient. CLINICAL TRIALS REGISTRATION: Clinical Trials No. NCT01538290.

Reproducibility of pulse wave analysis and pulse wave velocity in patients with type 2 diabetes.

AIMS: Patients with type 2 diabetes have increased arterial stiffness and a high incidence of cardiovascular disease compared with non-diabetics. Arterial stiffness and central waveforms can be assessed by carotid-femoral pulse wave velocity (PWV) and pulse wave analysis (PWA) using the SphygmoCor device. These methods can potentially improve cardiovascular risk stratification in the future. However, a prerequisite is acceptable reproducibility. The objective of this study was to assess the intra- and inter-observer reproducibility of PWV and PWA indices in patients with type 2 diabetes using the SphygmoCor device. METHODS: Two trained observers (A and B) each undertook two PWA and two carotid-femoral PWV recordings in random order in 20 patients with type 2 diabetes under standardized conditions on the right side of the patients. Observer A also made double recordings on the left side. The mean of the two recordings was used for inter-observer comparison. Data were analyzed by Bland-Altman plots. RESULTS: The mean intra-observer differences (± 2SD) on the right side for observer A and B, respectively, were 0.0 ± 2.8 mmHg and 0.3 ± 3.2 mmHg (aortic systolic blood pressue (BP)), 0.0 ± 1.2 mmHg and 0.1 ± 1.0 mmHg (aortic diastolic BP), - 1.1 ± 3.2% and 1.1 ± 9.6% (central augmentation index (Aix)), - 1.6 ± 6.6% and 0.1 ± 9.0% (Aix normalized to heart rate 75 beats/min (Aix@HR75)) and 0.1 ± 1.8 m/s and 0.0 ± 1.6 m/s (PWV). The mean inter-observer differences (± 2SD) were - 2.6 ± 13.0 mmHg (aortic systolic BP), - 2.1 ± 7.4 mmHg (aortic diastolic BP), - 0.8 ± 8.4% (Aix), - 1.5 ± 7.4% (Aix@HR75) and - 0.3 ± 1.6 m/s (PWV). Left-vs-right comparison showed comparable results (observer A). CONCLUSIONS: PWA and PWV assessed with the SphygmoCor device are characterized by good reproducibility in patients with type 2 diabetes.

A plea for consistent reliability in ambulatory blood pressure monitoring: an unusual case of software error in Spacelabs Report Management System 92506.

OBJECTIVE: Ambulatory blood pressure monitors are subject to extensive validation protocols, but no international guidelines on the software processing the collected raw data exist. Hence, there seems to be little or no control of ambulatory blood pressure monitoring (ABPM) software with respect to errors. In this paper, we wish to point out an important error in Spacelabs Report Management System 92506 software. METHODS: By chance, we noticed discrepancies in the Spacelabs Report Management System 92506 hourly average tabular as shown on-screen and on printout. To exclude the possibility of a random error, 97 ABPM reports were evaluated. In a random patient, we calculated the hourly averages by the arithmetic mean from all measurements. Similarly, the summary average of 24 h, daytime and night-time blood pressure was calculated both by the arithmetic mean of all measurements and by the mean of hourly averages in the respective periods. RESULTS: Evaluation of ABPM reports showed errors in 89 out of 97 (92%). In a random patient, the numerical difference between printout and on-screen hourly averages was considerable, ranging from -37 to 18 mmHg systolic and from -16 to 10 mmHg diastolic. Calculation on the basis of raw data established that on-screen hourly average tabular was correct, whereas printout values were erroneous. The erroneous values were also found in the exported hourly average tabular. CONCLUSION: If researchers base calculations on the use of erroneous data from printout or exported hourly average tabular, the results and hence the conclusions may be wrong. Focus on ABPM software is warranted.