Cardiovascular and health cost impacts of cuff blood pressure underestimation and overestimation of invasive aortic systolic blood pressure.

OBJECTIVE: Hypertension management is directed by cuff blood pressure (BP), but this may be inaccurate, potentially influencing cardiovascular disease (CVD) events and health costs. This study aimed to determine the impact on CVD events and related costs of the differences between cuff and invasive SBP. METHODS: Microsimulations based on Markov modelling over one year were used to determine the differences in the number of CVD events (myocardial infarction or coronary death, stroke, atrial fibrillation or heart failure) predicted by Framingham risk and total CVD health costs based on cuff SBP compared with invasive (aortic) SBP. Modelling was based on international consortium data from 1678 participants undergoing cardiac catheterization and 30 separate studies. Cuff underestimation and overestimation were defined as cuff SBP less than invasive SBP and cuff SBP greater than invasive SBP, respectively. RESULTS: The proportion of people with cuff SBP underestimation versus overestimation progressively increased as SBP increased. This reached a maximum ratio of 16 : 1 in people with hypertension grades II and III. Both the number of CVD events missed (predominantly stroke, coronary death and myocardial infarction) and associated health costs increased stepwise across levels of SBP control, as cuff SBP underestimation increased. The maximum number of CVD events potentially missed (11.8/1000 patients) and highest costs ($241 300 USD/1000 patients) were seen in people with hypertension grades II and III and with at least 15 mmHg of cuff SBP underestimation. CONCLUSION: Cuff SBP underestimation can result in potentially preventable CVD events being missed and major increases in health costs. These issues could be remedied with improved cuff SBP accuracy.

Accuracy of cuff blood pressure and systolic blood pressure amplification.

Automated cuff measured blood pressure (BP) is the global standard used for diagnosing hypertension, but there are concerns regarding the accuracy of the method. Individual variability in systolic BP (SBP) amplification from central (aorta) to peripheral (brachial) arteries could be related to the accuracy of cuff BP, but this has never been determined and was the aim of this study. Automated cuff BP and invasive brachial BP were recorded in 795 participants (74% male, aged 64 ± 11 years) receiving coronary angiography at five independent research sites (using seven different automated cuff BP devices). SBP amplification was recorded invasively by catheter and defined as brachial SBP minus aortic SBP. Compared with invasive brachial SBP, cuff SBP was significantly underestimated (130 ± 18 mmHg vs. 138 ± 22 mmHg, p < 0.001). The level of SBP amplification varied significantly among individuals (mean ± SD, 7.3 ± 9.1 mmHg) and was similar to level of difference between cuff and invasive brachial SBP (mean difference -7.6 ± 11.9 mmHg). SBP amplification explained most of the variance in accuracy of cuff SBP (R2 = 19%). The accuracy of cuff SBP was greatest among participants with the lowest SBP amplification (ptrend < 0.001). After cuff BP values were corrected for SBP amplification, there was a significant improvement in the mean difference from the intra-arterial standard (p < 0.0001) and in the accuracy of hypertension classification according to 2017 ACC/AHA guideline thresholds (p = 0.005). The level of SBP amplification is a critical factor associated with the accuracy of conventional automated cuff measured BP.

Sex Differences in Blood Pressure and Potential Implications for Cardiovascular Risk Management.

BACKGROUND: Accurate blood pressure (BP) measurement is critical for optimal cardiovascular risk management. Age-related trajectories for cuff-measured BP accelerate faster in women compared with men, but whether cuff BP represents the intraarterial (invasive) aortic BP is unknown. This study aimed to determine the sex differences between cuff BP, invasive aortic BP, and the difference between the 2 measurements. METHODS: Upper-arm cuff BP and invasive aortic BP were measured during coronary angiography in 1615 subjects from the Invasive Blood Pressure Consortium Database. This analysis comprised 22 different cuff BP devices from 28 studies. RESULTS: Subjects were 64±11 years (range 40-89) and 32% women. For the same cuff systolic BP (SBP), invasive aortic SBP was 4.4 mm Hg higher in women compared with men. Cuff and invasive aortic SBP were higher in women compared with men, but the sex difference was more pronounced from invasive aortic SBP, was the lowest in younger ages, and the highest in older ages. Cuff diastolic blood pressure overestimated invasive diastolic blood pressure in both sexes. For cuff and invasive diastolic blood pressure separately, there were sex*age interactions in which diastolic blood pressure was higher in younger men and lower in older men, compared with women. Cuff pulse pressure underestimated invasive aortic pulse pressure in excess of 10 mm Hg for both sexes in older age. CONCLUSIONS: For the same cuff SBP, invasive aortic SBP was higher in women compared with men. How this translates to cardiovascular risk prediction needs to be determined, but women may be at higher BP-related risk than estimated by cuff measurements.

Comparison between cuff-based and invasive systolic blood pressure amplification.

OBJECTIVE: Accurate measurement of central blood pressure (BP) using upper arm cuff-based methods is associated with several factors, including determining the level of systolic BP (SBP) amplification. This study aimed to determine the agreement between cuff-based and invasively measured SBP amplification. METHODS: Patients undergoing coronary angiography had invasive SBP amplification (brachial SBP - central SBP) measured simultaneously with cuff-based SBP amplification using a commercially available central BP device (device 1: Sphygmocor Xcel; n = 171, 70% men, 60 ±â€Š10 years) and a now superseded model of a central BP device (device 2: Uscom BP+; n = 52, 83% men, 62 ±â€Š10 years). RESULTS: Mean difference (±2SD, limits of agreement) between cuff-based and invasive SBP amplification was 4 mmHg (-12, +20 mmHg, P < 0.001) for device 1 and -2 mmHg (-14, +10 mmHg, P = 0.10) for device 2. Both devices systematically overestimated SBP amplification at lower levels and underestimated at higher levels of invasive SBP amplification, but with stronger bias for device 1 (r = -0.68 vs. r = -0.52; Z = 2.72; P = 0.008). Concordance of cuff-based and invasive SBP amplification across quartiles of invasive SBP amplification was low, particularly in the lowest and highest quartiles. The root mean square errors from regression between cuff-based central SBP and brachial SBP were significantly lower (indicating less variability) than from invasive regression models (P < 0.001). CONCLUSIONS: Irrespective of the difference from invasive measurements, cuff-based estimates of SBP amplification showed evidence of proportional systematic bias and had less individual variability. These observations could provide insights on how to improve the performance of cuff-based central BP.

Absolute risk assessment for guiding cardiovascular risk management in a chest pain clinic.

OBJECTIVES: To assess the efficacy of a pro-active, absolute cardiovascular risk-guided approach to opportunistically modifying cardiovascular risk factors in patients without coronary ischaemia attending a chest pain clinic. DESIGN: Prospective, randomised, open label, blinded endpoint study. SETTING: The rapid access chest pain clinic of Royal Hobart Hospital, a tertiary hospital. PARTICIPANTS: Patients who presented to the chest pain clinic between 1 July 2014 and 31 December 2017 who had intermediate to high absolute cardiovascular risk scores (5-year risk ≥ 8%). Patients with known cardiac disease or from groups with clinically determined high risk of cardiovascular disease were excluded. MAIN OUTCOME MEASURES: The primary endpoint was change in 5-year absolute risk score (Australian absolute risk calculator) at follow-up (at least 12 months after baseline assessment). Secondary endpoints were changes in lipid profile, blood pressure, smoking status, and body mass index, and major adverse cardiovascular events. RESULTS: The mean change in risk at follow-up was +0.4 percentage points (95% CI, -0.8 to 1.5 percentage points) for the 98 control group patients and -2.4 percentage points (95% CI, -1.5 to -3.4 percentage points) for the 91 intervention group patients; the between-group difference in change was 2.7 percentage points (95% CI, 1.2-4.1 percentage points). Mean changes in lipid profile, systolic blood pressure, and smoking status were larger for the intervention group, but not statistically different from those for the control group. CONCLUSIONS: An absolute cardiovascular risk-guided, pro-active risk factor management strategy employed opportunistically in a chest pain clinic significantly improved 5-year absolute cardiovascular risk scores. TRIAL REGISTRATION: Australia New Zealand Clinical Trial Registry, ACTRN12617000615381 (retrospective).

Identifying Isolated Systolic Hypertension From Upper-Arm Cuff Blood Pressure Compared With Invasive Measurements.

Isolated systolic hypertension (ISH) is the most common form of hypertension and is highly prevalent in older people. We recently showed differences between upper-arm cuff and invasive blood pressure (BP) become greater with increasing age, which could influence correct identification of ISH. This study sought to determine the difference between identification of ISH by cuff BP compared with invasive BP. Cuff BP and invasive aortic BP were measured in 1695 subjects (median 64 years, interquartile range [55-72], 68% male) from the INSPECT (Invasive Blood Pressure Consortium) database. Data were recorded during coronary angiography among 29 studies, using 21 different cuff BP devices. ISH was defined as ≥130/<80 mm Hg using cuff BP compared with invasive aortic BP as the reference. The prevalence of ISH was 24% (n=407) according to cuff BP but 38% (n=642) according to invasive aortic BP. There was fair agreement (Cohen κ, 0.36) and 72% concordance between cuff and invasive aortic BP for identifying ISH. Among the 28% of subjects (n=471) with misclassification of ISH status by cuff BP, 20% (n=96) of the difference was due to lower cuff systolic BP compared with invasive aortic systolic BP (mean, -16.4 mm Hg [95% CI, -18.7 to -14.1]), whereas 49% (n=231) was from higher cuff diastolic BP compared with invasive aortic diastolic BP (+14.2 mm Hg [95% CI, 11.5-16.9]). In conclusion, compared with invasive BP, cuff BP fails to identify ISH in a sizeable portion of older people and demonstrates the need to improve cuff BP measurements.

Excess pressure as an analogue of blood flow velocity.

INTRODUCTION: Derivation of blood flow velocity from a blood pressure waveform is a novel technique, which could have potential clinical importance. Excess pressure, calculated from the blood pressure waveform via the reservoir-excess pressure model, is purported to be an analogue of blood flow velocity but this has never been examined in detail, which was the aim of this study. METHODS: Intra-arterial blood pressure was measured sequentially at the brachial and radial arteries via fluid-filled catheter simultaneously with blood flow velocity waveforms recorded via Doppler ultrasound on the contralateral arm (n = 98, aged 61 ±â€Š10 years, 72% men). Excess pressure was derived from intra-arterial blood pressure waveforms using pressure-only reservoir-excess pressure analysis. RESULTS: Brachial and radial blood flow velocity waveform morphology were closely approximated by excess pressure derived from their respective sites of measurement (median cross-correlation coefficient r = 0.96 and r = 0.95 for brachial and radial comparisons, respectively). In frequency analyses, coherence between blood flow velocity and excess pressure was similar for brachial and radial artery comparisons (brachial and radial median coherence = 0.93 and 0.92, respectively). Brachial and radial blood flow velocity pulse heights were correlated with their respective excess pressure pulse heights (r = 0.53, P < 0.001 and r = 0.43, P < 0.001, respectively). CONCLUSION: Excess pressure is an analogue of blood flow velocity, thus affording the opportunity to derive potentially important information related to arterial blood flow using only the blood pressure waveform.

Validation Study to Determine the Accuracy of Central Blood Pressure Measurement Using the Sphygmocor Xcel Cuff Device.

Numerous devices purport to measure central (aortic) blood pressure (BP) as distinct from conventional brachial BP. This validation study aimed to determine the accuracy of the Sphygmocor Xcel cuff device (AtCor Medical, CardieX, Sydney, Australia) for measuring central BP. 296 patients (mean age 61±12 years) undergoing coronary angiography had simultaneous measurement of invasive central BP and noninvasive cuff-derived central BP using the Xcel cuff device (total n=558 individual comparisons). A subsample (n=151) also had invasive brachial BP measured. Methods were undertaken according to the Artery Society recommendations, and several calibration techniques to derive central systolic BP (SBP) were examined. Minimum acceptable error was ≤5±≤8 mm Hg. Central SBP was significantly underestimated, and with wide variability, when using the default calibration of brachial-cuff SBP and diastolic BP (DBP; mean difference±SD, -7.7±11.0 mm Hg). Similar variability was observed using other calibration methods (cuff 33% form-factor mean arterial pressure and DBP, -4.4±11.5 mm Hg; cuff 40% form-factor mean arterial pressure and DBP, 4.7±11.9 mm Hg; cuff oscillometric mean arterial pressure and DBP, -18.2±12.1 mm Hg). Only calibration with invasive central integrated mean arterial pressure and DBP was within minimal acceptable error (3.3±7.5 mm Hg). The difference between brachial-cuff SBP and invasive central SBP was 3.3±10.7 mm Hg. A subsample analysis to determine the accuracy of central-to-brachial SBP amplification showed this to be overestimated by the Xcel cuff device (mean difference 4.3±9.1 mm Hg, P=0.02). Irrespective of cuff calibration technique, the Sphygmocor Xcel cuff device does not meet the Artery Society accuracy criteria for noninvasive measurement of central BP.

The influence of SBP amplification on the accuracy of form-factor-derived mean arterial pressure.

OBJECTIVES: Accurate assessment of mean arterial pressure (MAP) is crucial in research and clinical settings. Measurement of MAP requires not only pressure waveform integration but can also be estimated via form-factor equations incorporating peripheral SBP. SBP may increase variably from central-to-peripheral arteries (SBP amplification), and could influence accuracy of form-factor-derived MAP, which we aimed to determine. METHODS: One hundred and eighty-eight patients (69% men, age 60 ±â€Š10 years) undergoing coronary angiography had intra-arterial pressure measured in the ascending aorta, brachial and radial arteries. Reference MAP was measured by waveform integration, and form-factor-derived MAP using 33 and 40% form-factors. RESULTS: Reference MAP decreased from the aorta to the brachial (-0.7 ±â€Š4.2 mmHg) and radial artery (-1.7 ±â€Š4.8 mmHg), whereas form-factor-derived MAP increased (33% form-factor 1.1 ±â€Š4.2 and 1.7 ±â€Š4.7 mmHg; 40% form-factor 0.9 ±â€Š4.8 and 1.4 ±â€Š5.4 mmHg, respectively). Form-factor-derived MAP was significantly different to reference aortic MAP (33% form-factor -2.5 ±â€Š4.6 and -1.6 ±â€Š5.8, P < 0.001; 40% form-factor 2.5 ±â€Š5.0 and 3.9 ±â€Š6.4 mmHg, P < 0.001, brachial and radial arteries, respectively), with significant variation in the brachial form-factor required (FFreq) to generate MAP equivalent to reference aortic MAP (FFreq range 20-57% brachial; 17-74% radial). Aortic-to-brachial SBP amplification was strongly related to brachial FFreq (r = -0.695, P < 0.001). The 33% form-factor was most accurate with high aortic-to-brachial SBP amplification (33% form-factor MAP vs. reference aortic MAP difference 0.06 ±â€Š3.93 mmHg, P = 0.89) but overestimated reference aortic MAP with low aortic-to-brachial SBP amplification (+5.8 ±â€Š4.6 mmHg, P < 0.001). The opposite was observed for the 40% form-factor. CONCLUSION: Due to variable SBP amplification, estimating MAP via form-factors produces nonphysiological inaccurate values. These findings have important implications for accurate assessment of MAP in research and clinical settings.

Development and Validation of an Atrial Fibrillation Knowledge Assessment Tool (AFKAT).

Assessing and improving public knowledge of atrial fibrillation (AF) could increase its detection rate and the subsequent use of stroke prevention therapies. However, there is no validated AF knowledge assessment tool applicable to the general population, including those at risk of AF. Therefore, we aimed to develop and validate such a tool. The tool was developed from a literature review and discussion with subject matter experts. Content validity was ensured by a ten-member panel of experts comprising cardiologists and pharmacists. An online validation survey was conducted and reported based on the Checklist for Reporting Results of Internet E-Surveys (CHERRIES). The survey evaluated the tool performance by construct validity, internal consistency reliability, item discrimination, difficulty index and ease of readability. The survey participants included 14 general medical specialists, 20 fourth-year and 33 second-year undergraduate pharmacy students, and 122 members of the general public. The tool had satisfactory content validity, with a scale content validity index of 0.8. The mean percentage knowledge scores for general medical specialists and fourth-year pharmacy students were higher than second-year pharmacy students, followed by the general public (92.9%, 87.6%, 68.5% and 53.4%, respectively; p-value < 0.001), supporting construct validity. The tool had good internal consistency reliability (Cronbach's alpha = 0.91). The item-total correlation was in the preferred range of 0.23 to 0.71. The Atrial Fibrillation Knowledge Assessment Tool is a valid instrument and can be used to investigate AF knowledge of the general population.

Associations of Reservoir-Excess Pressure Parameters Derived From Central and Peripheral Arteries With Kidney Function.

BACKGROUND: Central artery reservoir-excess pressure parameters are clinically important but impractical to record directly. However, diastolic waveform morphology is consistent across central and peripheral arteries. Therefore, peripheral artery reservoir-excess pressure parameters related to diastolic waveform morphology may be representative of central parameters and share clinically important associations with end-organ damage. This has never been determined and was the aim of this study. METHODS: Intra-arterial blood pressure (BP) waveforms were measured sequentially at the aorta, brachial, and radial arteries among 220 individuals (aged 61 ± 10 years, 68% male). Customized software was used to derive reservoir-excess pressure parameters at each arterial site (reservoir and excess pressure, systolic and diastolic rate constants) and clinical relevance was determined by association with estimated glomerular filtration rate (eGFR). RESULTS: Between the aorta and brachial artery, the mean difference in the diastolic rate constant and reservoir pressure integral was -0.162 S-1 (P = 0.08) and -0.772 mm Hg s (P = 0.23), respectively. The diastolic rate constant had the strongest and most consistent associations with eGFR across aortic and brachial sites (ß = -0.20, P = 0.02; ß = -0.20, P = 0.03, respectively; adjusted for traditional cardiovascular risk factors). Aortic, but not brachial peak reservoir pressure was associated with eGFR in adjusted models (aortic ß = -0.48, P = 0.02). CONCLUSIONS: The diastolic rate constant is the most consistent reservoir-excess pressure parameter, in both its absolute values and associations with kidney dysfunction, when derived from the aorta and brachial artery. Thus, the diastolic rate constant could be utilized in the clinical setting to improve BP risk stratification.

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.

Applying the Capability, Opportunity, and Motivation Behaviour Model (COM-B) to Guide the Development of Interventions to Improve Early Detection of Atrial Fibrillation.

OBJECTIVE: The primary objective of this study is to use the Capability, Opportunity, and Motivation Behaviour (COM-B) model to identify potential strategies aimed at improving the early detection of atrial fibrillation (AF) in the general population. METHODS: We undertook a review of the literature to identify factors associated with participation in community-based screening for AF, followed by mapping of the factors generated into the components of the COM-B model, and validation of the model by an expert panel. The Behaviour Change Wheel (BCW) was used to nominate potential intervention strategies and steps to guide the design and implementation of community-based screening for AF. RESULTS: A total of 28 factors from 21 studies were mapped into the COM-B model. Based on the BCW approach, 24 intervention strategies and 7 steps that could guide the design and implementation of community-based screening for AF were recommended. CONCLUSION: The application of the COM-B model demonstrated how factors influencing the participation of individuals with undiagnosed AF in community-based screening could be identified. The model could also serve as a guide for the design and implementation of interventions for improving AF detection in the general population.

Brachial and Radial Systolic Blood Pressure Are Not the Same.

Radial intra-arterial blood pressure (BP) is sometimes used as the reference standard for validation of brachial cuff BP devices. Moreover, there is an emerging wearables market seeking to measure BP at the wrist. However, radial systolic BP may differ when compared with brachial; yet some authors have labeled these differences as a fictional Popeye phenomenon. Indeed, differences between brachial and radial systolic BP have never been accurately quantified, and this was the aim of this study. Intra-arterial BP was measured consecutively at the brachial and radial artery in 180 participants undergoing coronary angiography (aged 61±10 years; 69% men). On average, radial systolic BP was 5.5 mm Hg higher than brachial systolic BP. Only 43% of participants had radial systolic BP within ±5 mm Hg of brachial. Additionally, 46%, 19%, and 13% of participants had radial systolic BP >5, between 5 and 10, and between 10 and 15 mm Hg higher than brachial respectively. A further 14% of participants had radial systolic BP >15 mm Hg higher than brachial, representing the so-called Popeye phenomenon. Finally, 11% of participants had radial systolic BP >5 mm Hg lower than brachial. In conclusion, radial systolic BP is not representative of brachial systolic BP, with most participants having a radial systolic BP >5 mm Hg higher than brachial and many with differences >15 mm Hg. Therefore, validation testing of BP devices utilizing intra-arterial BP as the reference standard should use intra-arterial BP measured at the same site as the brachial cuff or wearable device.

Intra-arterial analysis of the best calibration methods to estimate aortic blood pressure.

OBJECTIVE: Estimation of aortic blood pressure (BP) requires peripheral BP waveform calibration. Mean arterial pressure (MAP)/DBP calibration is purported to estimate aortic BP more accurately than SBP/DBP calibration. However, this is based on inaccurate cuff calibration. Thus, direct comparisons of each calibration method using intra-arterial BP are required to confirm this, and was the aim of this study. METHODS: Ascending aortic, brachial and radial artery intra-arterial BPs were measured among 107 patients (61.9 ±â€Š10.0 years, 70% men) undergoing coronary angiography. Radial waveforms were calibrated with brachial SBP/DBP and brachial MAP/DBP to directly test the accuracy of estimated aortic SBP (derived using a commercial device) from each calibration compared with intra-arterial aortic SBP. Estimated aortic BP accuracy from aortic MAP/DBP, brachial and radial SBP/DBP calibrations of peripheral waveforms was also tested (six calibration methods in total; all using intra-arterial BP). RESULTS: Estimated aortic SBP from brachial MAP/DBP calibration of radial waveforms had a significantly smaller mean difference than from brachial SBP/DBP calibration (-0.7 ±â€Š7.5 mmHg versus -6.9 ±â€Š7.3 mmHg, P < 0.0001 for difference). Of the other calibration methods, estimated aortic SBP was most accurate from aortic MAP/DBP calibration of radial waveforms (-1.8 ±â€Š5.0 mmHg, P = 0.00023). However, for all calibration methods, aortic-to-brachial artery and/or brachial-to-radial artery SBP amplification had a major influence on estimated aortic SBP. CONCLUSION: Brachial and aortic MAP/DBP were confirmed as the best calibration methods to estimate aortic SBP, but irrespective of calibration method, accuracy was significantly influenced by the level of SBP amplification. Thus, improved accuracy of estimated aortic SBP should be possible by closer consideration of SBP amplification or individual waveform characteristics that differ according to the level of SBP amplification.

Non-invasive measurement of reservoir pressure parameters from brachial-cuff blood pressure waveforms.

Reservoir pressure parameters [eg, reservoir pressure (RP) and excess pressure (XSP)] are biomarkers derived from blood pressure (BP) waveforms that have been shown to predict cardiovascular events independent of conventional cardiovascular risk markers. However, whether RP and XSP can be derived non-invasively from operator-independent cuff device measured brachial or central BP waveforms has never been examined. This study sought to achieve this by comparison of cuff reservoir pressure parameters with intra-aortic reservoir pressure parameters. 162 participants (aged 61 ± 10 years, 72% male) undergoing coronary angiography had the simultaneous measurement of cuff BP waveforms (via SphygmoCor XCEL, AtCor Medical) and intra-aortic BP waveforms (via fluid-filled catheter). RP and XSP derived from cuff acquired brachial and central BP waveforms were compared with intra-aortic measures. Concordance between brachial-cuff and intra-aortic measurement was moderate-to-good for RP peak (36 ± 11 vs 48 ± 14 mm Hg, P < 0.001; ICC 0.77, 95% CI: 0.71-0.82), and poor-to-moderate for XSP peak (28 ± 10 vs 24 ± 9 mm Hg, P < 0.001; ICC 0.49, 95% CI: 0.35-0.60). Concordance between central-cuff and intra-aortic measurement was moderate-to-good for RP peak (35 ± 9 vs 46 ± 14 mm Hg, P < 0.001; ICC 0.77, 95% CI: 0.70-0.82), but poor for XSP peak (12 ± 3 vs 24 ± 9 mm Hg, P < 0.001; ICC 0.12, 95% CI: -0.13 to 0.31). In conclusion, both brachial-cuff and central-cuff methods can reasonably estimate intra-aortic RP, whereas XSP can only be acceptably derived from brachial-cuff BP waveforms. This should enable widespread application to determine the clinical significance, but there is significant room for refinement of the method.

Discovery of New Blood Pressure Phenotypes and Relation to Accuracy of Cuff Devices Used in Daily Clinical Practice.

Cuff blood pressure (BP) is the reference standard for management of high BP, but the method is inaccurate and can lead to BP misclassification. The aims of this study were to determine whether distinctive BP phenotypes exist based on BP transmission (amplification) variability from central-to-peripheral arteries and whether applying one standard cuff BP measurement approach (eg, oscillometry) to all people could discriminate the BP phenotypes. Intra-arterial BP was measured at the ascending aorta and brachial and radial arteries in 126 participants (61±10 years; 69% male) after coronary angiography. Central-to-peripheral systolic BP (SBP) transmission (SBP amplification) was defined by ≥5 mm Hg SBP increase between the aorta-to-brachial or brachial-to-radial arteries. Standard cuff BP was measured 4 different times using 3 different devices. Three independent investigators also provided data (n=255 from 4 studies) using another 3 separate cuff BP devices. Four distinct BP phenotypes were discovered based on variability in SBP amplification: phenotype 1, both aortic-to-brachial and brachial-to-radial SBP amplification; phenotype 2, only aortic-to-brachial SBP amplification; phenotype 3, only brachial-to-radial SBP amplification; and phenotype 4, neither aortic-to-brachial nor brachial-to-radial SBP amplification. Aortic SBP was significantly higher among phenotypes 3 and 4 compared with phenotypes 1 and 2 (P=0.00074), but this was not discriminated using any standard cuff BP measures (P=0.31). Data from independent investigators confirmed the key findings. This is the first-in-human discovery of BP phenotypes that have significantly different BPs, but which are not discriminated by standard cuff BP devices used in daily clinical practice. Improved BP device accuracy may be achieved by considering individual phenotypic BP differences.

Identification of the Optimal Protocol for Automated Office Blood Pressure Measurement Among Patients With Treated Hypertension.

BACKGROUND: Automated office blood pressure (AOBP) involving repeated, unobserved blood pressure (BP) readings during one clinic visit is recommended for in-office diagnosis and assessment of hypertension. However, the optimal AOBP protocol to determine BP control in the least amount of time with the fewest BP readings is yet to be determined and was the aim of this study. METHODS: One hundred and eighty-nine patients (mean age 62.8 ± 12.1 years; 50.3% female) with treated hypertension referred to specialist clinics at 2 sites underwent AOBP in a quiet room alone. Eight BP measurements were taken starting immediately after sitting and then at 2-minute intervals (15 minutes total). The optimal AOBP protocol was defined by the smallest mean difference and highest intraclass correlation coefficient (ICC) compared with daytime ambulatory BP (ABP). The same BP device (Mobil-o-graph, IEM) was used for both AOBP and daytime ABP. RESULTS: Average 15-minute AOBP and daytime ABP were 134 ± 22/82 ± 13 and 137 ± 17/83 ± 11 mm Hg, respectively. The optimal AOBP protocol was derived within a total duration of 6 minutes from the average of 2 measures started after 2 and 4 minutes of seated rest (systolic BP: mean difference (95% confidence interval) 0.004(-2.21, 2.21) mm Hg, P = 1.0; ICC = 0.81; diastolic BP: mean difference 0.37(-0.90, 1.63) mm Hg, P = 0.57; ICC = 0.86). AOBP measures taken after 8 minutes tended to underestimate daytime ABP (whether as a single BP or the average of more than 1 BP reading). CONCLUSIONS: Only 2 AOBP readings taken over 6 minutes (excluding an initial reading immediately after sitting) may be needed to be comparable with daytime ABP.