Association of lower nighttime diastolic blood pressure and hypoxia with silent myocardial injury: The Japan Morning Surge‐Home Blood Pressure study

Whether marked nocturnal blood pressure (BP) reduction is associated with cardiovascular disease (CVD) is still controversial. In addition, no report has yet discussed the relationship between lower nocturnal BP and CVD, involving modification by nighttime hypoxia. We evaluated 840 patients who had one or more cardiovascular risk factors by measuring their high‐sensitivity cardiac troponin T (Hs‐cTnT), N‐terminal pro‐B‐type natriuretic peptide (NT‐pro BNP), and nighttime saturation levels and performing ambulatory BP monitoring. The lowest tertile in nighttime diastolic BP (DBP) (≤66 mmHg) had increased likelihood of the presence of ≥0.014 ng/ml of Hs‐cTnT compared with the second tertile (odds ratio [OR] 1.91, 95% confidence interval [CI] 1.01–3.63), and the lowest tertile of minimum blood oxygen saturation (≤81%) had increased likelihood of the presence of ≥0.014 ng/ml of Hs‐cTnT compared with the third tertile (OR 2.15, 95% CI 1.13–4.10). Additionally, the patients with both lowest tertile of nighttime DBP and minimum SpO2 showed increased likelihood of the presence of ≥0.014 ng/ml of Hs‐cTnT compared with those without this combination (OR 2.93, 95% CI 1.40–6.16). On the other hand, these associations were not found in the presence of ≥125 pg/ml of NT‐pro BNP. In the clinical population, each of lower nocturnal DBP and nighttime hypoxia was associated with asymptomatic myocardial injury, which was represented as higher Hs‐cTnT, and coexisting lower nocturnal DBP and nighttime hypoxia had an additive effect on the risk of myocardial injury.