key: cord-0860408-08gol5f5
authors: Shan, Rongzi; Ding, Jie; Weng, Daniel; Spaulding, Erin M.; Wongvibulsin, Shannon; Lee, Matthias A.; Demo, Ryan; Marvel, Francoise A.; Martin, Seth S.
title: Early Blood Pressure Assessment after Acute Myocardial Infarction: Insights Using Digital Health Technology
date: 2020-09-17
journal: Am J Prev Cardiol
DOI: 10.1016/j.ajpc.2020.100089
sha: c1cd1deb2cc68e4b586044449428bf906b74050f
doc_id: 860408
cord_uid: 08gol5f5

OBJECTIVE: There is rising interest in digital health in preventive cardiology, particularly for blood pressure (BP) management. In a digital health study of early BP assessment following acute myocardial infarction (AMI), we sought to examine feasibility and the (1) proportion of post-AMI patients with controlled BP and hypotension, and (2) association between prior cardiovascular disease (CVD) and BP post-AMI. METHODS: In this substudy of the parent Myocardial infarction, COmbined-device, Recovery Enhancement (MiCORE) study, type 1 AMI patients were enrolled between October 2017 and April 2019. Participants self-monitored their BP through 30 days after hospital discharge using an FDA-approved wireless BP monitor connected with a smartphone application. Linear mixed-effects models assessed the association between prior CVD and BP trajectory post-discharge, adjusting for antihypertensive medications and a propensity score inclusive of CVD risk factors. RESULTS: Sixty-eight AMI patients (mean age 58±10 years, 75% male, 68% white race, 68% history of hypertension, 24% prior CVD) provided 2,638 measurements over 30 days. The percentage of BP control <130/80 mmHg was 59.6% (95% CI: 54.3 - 64.9%) and <140/90 mmHg was 83.7% (95% CI: 80.3-87.2%). The percentage of systolic BP <90 mmHg was 1.1% (95% CI: 0.17-2.0%) and the percentage of diastolic BP <60 mmHg was 3.9% (95% CI: 2.6-5.2%). Prior CVD was associated with 12.2 mmHg higher mean daily systolic BP during admission (95% CI: 3.5-20.9 mmHg), which persisted over follow-up. There was no association between prior CVD and diastolic BP. CONCLUSION: The digital health program was feasible and ∼40% of post-AMI patients who engaged in it had uncontrolled BP according to recent guideline cutpoints, while hypotension occurred rarely. The gap in BP control was especially large in patients in whom AMI represented recurrent CVD. These data suggest an opportunity for more aggressive secondary prevention early after MI as care models integrate digital health.

Every year in the United States, approximately 605,000 individuals experience their first acute myocardial infarction (AMI), and about 200,000 suffer recurrent AMIs. 1 Secondary prevention strategies, which include smoking cessation, adherence to cardioprotective medications, cardiac rehabilitation, and management of weight, lipids, diabetes, and blood pressure (BP), reduce the recurrence of cardiovascular events. 2 BP monitoring is one important component of management following AMI, and self-monitored BP have potential to improve the diagnosis and management of hypertension. 3 The 2011

American Heart Association/American College of Cardiology (AHA/ACC) secondary prevention guidelines for patients with atherosclerotic cardiovascular disease (CVD) emphasize BP control to <140 mmHg systolic and <90 mmHg diastolic. 2 The 2017 AHA/ACC Clinical Practice Guidelines for hypertension lowered the BP goal to <130 mmHg systolic and <80 mmHg diastolic, 4, 5 The early post-discharge period is a particularly vulnerable time, in which patients transition from having inpatient vitals monitored multiple times a day with close titration of antihypertensives to outpatient care with fewer assessments of vitals and adjustment of antihypertensives. Digital health interventions (DHIs) have shown early potential to increase patient adherence to guideline-based therapies and attainment of BP targets as well as allow for collection of more granular data to assess whether treatment goals are met. 6, 7 Given the importance of secondary prevention in reducing AMI recurrence, we hypothesized that there would be differences in early BP trajectories between participants with and without CVD prior to the index AMI. Greater atherosclerotic burden in CVD may contribute to these differences. In this feasibility study, we investigate BP patterns among AMI patients who self-monitored their BP using Corrie, a DHI that educates patients on secondary prevention and facilitates BP monitoring and medication tracking, over 30 days post-hospital discharge. In this descriptive analysis of post-AMI patients, we examined the (1) prevalence of controlled BP as defined by 2017 and 2011 AHA/ACC guidelines, 2, 4 (2) prevalence of J o u r n a l P r e -p r o o f systolic hypotension (<90 mmHg) or diastolic hypotension (<60 mmHg), 8,9 and (3) associations between prior CVD and BP during admission and trajectories after discharge.

This analysis included a subset of participants enrolled in the Myocardial infarction, Combineddevice, Recovery Enhancement (MiCORE) study, which has been previously described, 10 or Type 1 non ST-elevation myocardial infarction (NSTEMI) were enrolled with the Corrie intervention during admission and were followed for 30 days post-discharge from the hospital. Inclusion criteria in addition to type 1 AMI were: (1) 18 years or older, (2) owned a smartphone, and (3) approved to participate by their inpatient care team. Exclusion criteria were: (1) non-English speaking, (2) had a visual, auditory, cognitive, or motor impairment that would interfere with smartphone usage, or (3) hemodynamically unstable. To reduce selection bias, participants who did not own an iPhone were given a loaner phone to use for the duration of the study. 11, 12 Data exclusion criteria for this sub-study analysis were: (1) BP values outside of the manufacturer-specified measurement ranges of 60-260 mmHg systolic BP or 40-199 mmHg diastolic BP, 13 (2) participants who were not given an iHealth BP monitor (due to participation during the pilot phase or lack of cuff availability in appropriate size) to minimize erroneous values, 10 The Corrie Health digital platform integrated with the FDA-approved iHealth Bluetooth BP monitor (iHealth Lab Inc., BP3L), which allowed participants to monitor, save, and review BP recordings in the hospital and post-discharge with Corrie. A description of the Corrie smartphone application (app) and screenshots are available in Supplemental Figure. The app provided participants the opportunity to check their blood pressure up to four times a day (i.e. morning, noon, afternoon, and evening) during their inpatient and home self-monitoring. At the time of enrollment, patients were instructed to input their vitals regularly (preferably daily), but the frequency and timing of the self-monitored BPs were left to their own discretion. During the enrollment process, participants had their arm circumference Participants could also choose to share their self-monitored BP measurements with clinicians on their own. After hospital discharge, participants had no scheduled appointments with the study team. BP control by the 2011 AHA/ACC guidelines 2 was defined as systolic BP <140 mmHg and diastolic BP <90 mmHg. BP control by the 2017 AHA/ACC guidelines 4 was defined as systolic BP <130 mmHg and diastolic BP <80mmHg. We also assessed the proportion of hypotension, analyzing the proportion of mean systolic BP <90 mmHg 8 and mean diastolic BP <60 mmHg 9 separately. These proportions in the presence of binary measures repeated within a day in turn nested within persons were estimated by performing a linear regression on a constant and using the cluster-robust estimator of variance to relax the assumption of the independence of the observations. Using a double cluster identifier, we grouped the observations by participant and time of day. Additionally, we assessed whether any measurements were within hypertensive crisis range (systolic BP >180 mmHg and/or diastolic BP >120 mmHg). 4 We used random-intercept and random-slope multivariable linear mixed models to estimate whether the association between history of prior CVD and mean daily BP changed across time during the 30 days post-discharge. To account for within-subject correlations of repeated BP measures, we used the random-coefficient structure, in which the covariances depend on the random effects and the correlation between intercept and slope. To test whether longitudinal within-subject changes in BP J o u r n a l P r e -p r o o f varied between patients with and without prior CVD, the model included the interaction between prior CVD and continuous study days (Day 0 -30, with Day 0 representing mean BP measures during admission and Day 1 corresponding to the first day after hospital discharge). This assumed linear changes over time. The models controlled for CVD risk factors and number of antihypertensive medications prescribed at discharge (inclusive of beta blockers, calcium channel blockers, diuretics, and angiotensin converting enzyme inhibitors/angiotensin receptor blockers). In order not to overfit the statistical models, we used logistic regression to compute propensity scores for prior CVD risk. In this model, binary prior CVD status was the dependent variable, and the following cardiovascular risk factors were independent covariates: age, sex, race, hypertension, type 2 diabetes, hyperlipidemia, and ever smoker. 14 The estimated propensity score was the derived predicted value of this equation and all models were adjusted for the quintiles of the propensity score. To account for the potential effect of self-monitoring on BP outcomes, we ran a sensitivity analysis that added number of BP measurements as a covariate. To investigate associations between prior CVD and change in BP measured at specific times of the day over follow-up, the model was also applied to individual time period measurements of systolic and diastolic BP. Differences with p-values <0.05 were considered statistically significant. All analyses were performed using Stata version 15.1.

Of the 200 MiCORE participants, 129 received an iHealth BP monitor. For the BP data, we first excluded 12 observations from 8 individuals which were outside of the manufacturer-specified measurement ranges 13 or for which systolic BP was less than diastolic BP. After applying further data exclusion criteria, there were 68 participants with BP values measured on at least 2 days in the 30-day period after discharge who were included in the current analysis ( Table 1 . They were mean age 58±10 years, 25% women, 68% white race, 44% with bachelor's degree or higher education level, and 40% had Medicare or Medicaid insurance. Patients admitted for STEMI comprised 49% of participants, while the remainder were admitted for Type 1 NSTEMI, with 24% having a prior history of CVD and 68% having a history of hypertension. The frequency of antihypertensive medications prescribed at the time of discharge were: 92.7% beta blockers, 54.4% angiotensin converting enzyme inhibitors/angiotensin receptor blockers, 33.8% diuretics, and 10.3% calcium channel blockers. Compared to participants who received an iHealth BP monitor but did not provide sufficient data (n=61), the participants included in this analysis (n=68) less likely to have prior CVD or MI, and more likely to have complete revascularization during admission.

Although not statistically significant, participants included in the analysis were less often on Medicare or Medicaid insurance (Table 1) .

Overall, there were a total of 150 time period-averaged BP measurements (mean 2. Table 1 ). The interaction between history of CVD and study day was not significant ( Table 3) . Thus, we did not detect a difference in change in mean daily systolic BP over 30 days between those who had prior CVD and those who did not. Figure 3 shows the predicted trajectories of mean daily systolic BP values during admission and over 30 days of follow-up, based on the mixed effects model. There was no association between prior CVD and diastolic BP during admission or with regards to change over 30 days of follow-up ( Table 3 ). In the sensitivity analysis, adding the total number of BP measurements during the study as a covariate in the above model revealed similar results: a history of prior CVD was associated with 11.8 mmHg higher systolic BP during admission (95% CI 3.1 -20.4), and the interaction term between history of CVD and study day remained non-significant.

When looking at the trends in systolic BP by time period, the same pattern of higher systolic BP during admission in patients with prior CVD than those without prior CVD held for the BP measurements taken at night and noon, but not for the morning, afternoon, or evening measurements. There was no evidence of interaction between history of CVD and study day on the outcome of systolic BP measurements over any of the time periods. Table 4 summarizes the results of the models and J o u r n a l P r e -p r o o f Assessment of BP After MI 9 interactions for each time period. There were no significant associations between prior CVD and diastolic BP within the same time periods during admission or over follow-up.

This study demonstrates that, in an older and higher-risk sample, self-monitored BP using a DHI was feasible, reflects clinical characteristics, and can provide insight into quality of care. In the early post-AMI recovery period, we found suboptimal rates of BP control (59.6%) by the 2017 AHA/ACC hypertension guidelines and higher rates of control (83.7%) by the 2011 AHA/ACC secondary prevention guidelines. The proportion of systolic or diastolic BP in the hypotensive range was relatively low, and no participants recorded time period averaged values greater than the hypertensive crisis threshold of 180/120 mmHg. A history of prior CVD, which suggests inadequate secondary prevention in the past and greater vasculopathy, was associated with higher mean systolic BP during admission but not with change rate over 30 days post-discharge.

The suboptimal rates of BP control in the early post-AMI recovery period represents an addressable target for CVD risk modification. Specifically, as patients transition from frequent vitals monitoring in the hospital to outpatient care, there is a need to provide early identification of patients with uncontrolled BP who may need nonadherence counselling, lifestyle modification, or intensification of antihypertensive drug therapy. Furthermore, because these data are from 2017-2019, the gap between 59.6% of participants meeting the 2017 guidelines versus 83.7% of participants meeting the 2011 guidelines may represent a delay in adoption, confusion around the guidelines, or simply that the newer target is harder to attain. Additionally, the suboptimal rates of BP control may represent clinical caution to avoid overtreatment. [15] [16] [17] [18] Nevertheless, the ability of DHIs to provide home BP monitoring can help catch episodes of hypotension and support individualized therapeutic goals. 15 

By suggesting a relationship between prior atherosclerotic disease and higher systolic BP during admission after AMI, without difference in rate of change over 30 days post-discharge, this study underscores the importance of secondary prevention. Although the predicted values of mean daily systolic BP in the CVD and non-CVD group appear to converge over time (Figure 3) , this relationship was non-significant, which may be due to variability, small sample size, or an attenuating effect of the DHI.

Given that atherosclerosis and age are associated with increased pulse pressure 19 with lower diastolic BP and higher systolic BP, it is unsurprising that we did not find any association between diastolic BP and prior CVD. This also aligns with the relatively higher percentage of diastolic hypotension (3.9%) compared with systolic hypotension (1.1%).

Our finding that the association between prior CVD and higher systolic BP was most pronounced in measurements between the hours of 0000 -0759 fits with known patterns in the circadian rhythm of BP. 20 Specifically, the difference in systolic BP between participants with and without prior CVD was of a greater magnitude in the night/early morning hours (0000-0759), coinciding with awakening from overnight sleep. This enhanced nighttime difference could also reflect the increased risk of cardiovascular events seen in patients who lack nocturnal BP dipping. 20 It is important to note that these findings are exploratory, and the lack of significance in morning, afternoon, and evening measurements may represent insufficient power and/or less variation in BP compared to nighttime measurements.

These time period patterns underscore the importance of examining more granular data, which is a unique strength of DHIs. Future studies using digital health data should assess both population-based and individual-based longitudinal trends, as well as account for within-day variation.

The Corrie Health Digital Platform is undergoing clinical validation, 10 and the iHealth Bluetooth BP monitor has been validated for measurement accuracy. 13 This is an important strength in the nascent digital health field, as many commercially available DHIs for BP have not been clinically studied and some home BP measurement devices may be of unclear accuracy. 21, 22 This study is in line with the J o u r n a l P r e -p r o o f Assessment of BP After MI 11 overall progression towards using digital health to collect more frequent and real-time data to inform clinical decisions. For an individual patient, their home BP trend is likely more valuable for medication titration than single in-clinic values, which have been used in DHIs for hypertension. 7, 23 In the post-AMI population, a randomized clinical trial from the Netherlands 24 found no difference in proportion of BP control by the 140/90 goal among patients using DHI-enabled BP selfmonitoring at 1 year after AMI compared with usual care. However, this study only incorporated 4 follow-up visits over 1 year, while more frequent medication titration based on home BP trends may be necessary to fully utilize the benefits of BP self-monitoring. This trial found 76% control by the 140/90 mmHg goal, as measured in clinic 1 year after AMI among patients in their DHI arm. While this value is lower than our finding of 83.7% control by the 140/90 mmHg goal in the first 30 days post-AMI, this difference may be attributed to factors such as time after AMI, clinical and demographic differences, and type of BP measurement (in-clinic in the trial by Treskes and colleagues 24 versus at-home in our study).

The BP measurements in this study are limited by possible inaccuracies from patient selfmonitoring. We were unable to enforce proper measurement techniques, but we ameliorated this by restricting the analysis to only iHealth users, so the measurements would flow directly from the monitoring device. Research staff also instructed participants on the proper methods of BP measurement. It is also possible that the iHealth BP3L monitors overestimated BP, as a comparison study in 43 post-AMI patients found a +5.0 mmHg mean difference in systolic BP in the iHealth BP5 compared to a manual sphygmomanometer. 25 Additionally, this study was limited by a small sample size and selection bias, as participants selfselected whether to monitor their BP and were not required to use the BP monitor daily. This is reflected in the relatively high percentage of missing data and in the differences between participants included in this analysis and participants who did not contribute sufficient data. The association J o u r n a l P r e -p r o o f between prior CVD and systolic BP after AMI should be considered in the context of the sample population having lower proportion of prior CVD and higher proportion of first-time AMI and complete revascularization (perhaps indicating lower burden of disease) than those who did not provide sufficient BP measures. First-time AMI patients may have needed more resources during recovery and thus selfselected to use the Corrie DHI more frequently. Notably, Hispanic/Latino patients were underrepresented in our sample, in part due to the Corrie app being only available in English at the time of this study. However, since the start of this study, Corrie has been translated into Spanish with plans for future versions of Corrie to include other languages.

Nevertheless, given the increasing prevalence of mobile device ownership, DHIs have the potential to improve access to healthcare among underserved patients, some of whom rely on mobile devices to obtain access to the internet. 26 For some patients with limited transportation, insurance coverage, or time, a mobile app may especially increase access to care over in-person sessions. 12 In future practice, the integration of digital heath into BP evaluation requires systems that would allow clinicians to prescribe DHIs and for it to be reimbursed by payers. This is especially pertinent in the COVID-19 pandemic, as many health systems have increasingly adopted telehealth models. 27 By providing devices and support to patients of all demographics, we can leverage the benefits of DHIs for health equity.

Only 59.6% of early AMI patients had mean daily BP measurements meeting the guideline-based Table 3 : Prior cardiovascular disease (CVD) and subsequent day-averaged blood pressure levels during 30-day post-discharge. Results were determined using linear mixed-effects modelling, adjusting for propensity score inclusive of CVD risk factors, number of antihypertensive medications prescribed at discharge, and the interaction between prior CVD and time. Number of participants = 68; number of observations = 1,197.

Systolic BP Beta coefficient (95% CI) Diastolic BP Beta coefficient (95% CI) J o u r n a l P r e -p r o o f Table 4 : Association between history of cardiovascular disease (CVD) and systolic blood pressure (BP) during admission and over 30 days post-discharge after acute myocardial infarction (AMI), by time period of BP measurement. Results were determined using linear mixed-effects modelling, adjusting for propensity score inclusive of CVD risk factors, number of antihypertensive medications prescribed at discharge, and the interaction between prior CVD and time. 

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We thank the participants of the MiCORE study. Additionally, we thank Nucleus Medical Media for providing educational medical animations and video content for use in the Corrie application, the Apple