Morning home BP a strong predictor of CAD
By Dr. Reuben Ricallo
IT IS WELL established that clinic blood pressure (CBP) is strongly predictive of stroke events. The data however is not that robust to link it with coronary artery disease (CAD).
Saito K et al. conducted a study [J Am Coll Cardiol. 2016;67(13):1519-1527] which compared the relationships of morning home BP (HBP) or CBP with the incidence of CAD (myocardial infarction and revascularization for angina) and stroke events, using data from the large real-world prospective HONEST study, which was a large-scale prospective, real-world observational study.
The authors noted that data from a large-scale database study revealed that 24-hour diastolic BP (DBP) and isolated diastolic hypertension predict CAD in untreated people younger than 50 years of age, while other studies showed a correlation between home HBP and CV events; but the relationship between HBP and CAD events was not reported.
Advantages of HBP include being easy to measure, and it can provide repeated measures and long-term monitoring. Before this study, the best time of day for HBP measurement which can predict CAD events remained to be determined. However, it has been previously shown that morning hypertension predicts CV events, since both incidence of CV events and BP peak in the early morning.
The authors reported the following main results:
•127 stroke (2.92 per 1000 patient-years, PY) and 121 CAD events (2.78 per 1000 PY) occurred in 21591 patients (mean follow-up: 2.02+0.50 years).
•Incidence and HR of stroke and CAD events numerically increased in ascending categories of HSBP and CSBP, with statistically significantly higher incidences if HSBP>145 and CSBP>150 mmHg.
•HR for stroke events was significantly higher if morning HSBP>155, as compared with morning HSBP<125 mmHg (HR: 6.01, CI: 2.85-12.68). At morning HSBP from 145 to 155 mmHg, a tendency towards higher stroke event risk as compared with those with <125 mmHg was seen (HR: 1.90, CI: 0.90-3.99, P=0.091).
•Evening HSBP >145 mmHg was also associated with higher incidence and HR of stroke.
•Morning and evening HSBP predicted stroke events to a similar extent as does CSBP.
•Patients with morning HSBP>155 mmHg had significantly higher CAD event risk than those with <125 mmHg (HR: 6.24, CI: 2.82-13.84), and a tendency of a higher risk was seen in those with morning HSBP between 145 and 155 mmHg (HR: 2.15, CI: 0.98-4.71, P=0.056). Evening HSBP >155 mmHg showed a significantly higher incidence and HR of CAD events, but not evening HSBP between 145 and 155 mmHg. HR for CAD was significantly higher only when CSBP>160 mmHg (HR: 3.51, CI: 1.71-7.20).
•No evidence was seen for a J-curve phenomenon in the relationship between morning HBP and stroke or CAD events.
•Addition of morning HSBP significantly improved goodness-of-fit of a model for stroke or CAD events including CSBP. Adding CSBP to a model including morning HSBP significantly but more weakly improved the goodness-of-fit for a stroke model, but did not improve the CAD events model.
•Both higher stroke and CAD event risk were seen in morning HDSP>90 vs. <75 mmHg.
Based on their findings, the authors concluded that their data “show that morning HBP is a strong predictor of future CAD events, as well as stroke events. CSBP and evening SBP may underestimate CAD risk, as compared with morning HSBP. Morning HDBP and CDBP appear to underestimate the risk of CAD events as compared with morning HSBP or CSBP. Thus, morning HSBP may be a superior predictor of future CAD. No evidence of a J-curve in the relationship between morning HBP and stroke or CAD event risk was seen.”
What may be considered a potential bias for the study was that it used data of four HBP measurements, which was compared with a single CBP measurement. The observed superiority of morning HBP may be possibly due to the multiple HBP measurements, although from the practical standpoint, this is not a problem since repeated HBP measurements are not difficult to do.
An accompanying editorial comment noted that in connection with the debate on the ideal BP target, “the notion that home BP measurements have greater prognostic significance than clinic BP deserves attention.” The editorial explained that physicians appear more likely to increase antihypertensive drugs based on the home BP measurements, “thus home BP measurements may reduce therapeutic inertia and improve hypertension control.”
“The study in fact reported evening home BP and overall home BP (the average of morning and evening BPs), and the data show that using all home BP recordings instead of just the morning ones may be easier and at least as strongly associated if not more strongly associated with stroke and coronary artery disease. Thus, this study does not specifically demonstrate the value of morning home BP over the overall home BP.”
It added that it is time to design a randomized trial similar to SPRINT with treatment targets dictated by—not clinic BP—but home BP assessments. “If home BP can predict cardiovascular outcomes at least as well as clinic BP, it is time to test this strategy for cost-effectiveness, convenience, and, ultimately, its capability to relieve cardiovascular morbidity and mortality with the simple expedient of home BP monitoring.” With a JACC report
Vital Signs Issue 86 Vol. 4, April 1-30 2016