Background: We and other investigators previously reported that isolated nocturnal hypertension on ambulatory measurement (INH) clustered with cardiovascular risk factors and was associated with intermediate target organ damage. We investigated whether INH might also predict hard cardiovascular endpoints.
Methods and results: We monitored blood pressure (BP) throughout the day and followed health outcomes in 8711 individuals randomly recruited from 10 populations (mean age 54.8 years, 47.0% women). Of these, 577 untreated individuals had INH (daytime BP <135/85 mmHg and night-time BP ≥120/70 mmHg) and 994 untreated individuals had isolated daytime hypertension on ambulatory measurement (IDH; daytime BP ≥135/85 mmHg and night-time BP <120/70 mmHg). During follow-up (median 10.7 years), 1284 deaths (501 cardiovascular) occurred and 1109 participants experienced a fatal or nonfatal cardiovascular event. In multivariable-adjusted analyses, compared with normotension (n = 3837), INH was associated with a higher risk of total mortality (hazard ratio 1.29, P = 0.045) and all cardiovascular events (hazard ratio 1.38, P = 0.037). IDH was associated with increases in all cardiovascular events (hazard ratio 1.46, P = 0.0019) and cardiac endpoints (hazard ratio 1.53, P = 0.0061). Of 577 patients with INH, 457 were normotensive (<140/90 mmHg) on office BP measurement. Hazard ratios associated with INH with additional adjustment for office BP were 1.31 (P = 0.039) and 1.38 (P = 0.044) for total mortality and all cardiovascular events, respectively. After exclusion of patients with office hypertension, these hazard ratios were 1.17 (P = 0.31) and 1.48 (P = 0.034).
Conclusion: INH predicts cardiovascular outcome in patients who are normotensive on office or on ambulatory daytime BP measurement.