Midlife Blood Pressure Change and Left Ventricular Mass and Remodelling in Older Age in the 1946 British Birth Cohort Study
What is the relationship of antecedent blood pressure to the subsequent development of left ventricular (LV) hypertrophy?
The patients reported in the study are from the British 1946 Birth Cohort study, which included all births in a single week of March 1946 in England, Scotland, and Wales. During this time, there were 5,362 births. Data presented in this study include blood pressure obtained at the ages of 36, 43, 53, as well as evaluation between the ages of 60 and 64 (October 2006 to February 2011) that included an echocardiogram for determination of LV mass index (LVMI). Throughout the course of the study, patients were managed by personal physicians without specific protocols for blood pressure management or management of comorbidities.
There were 1,653 subjects who had complete follow-up and an echocardiogram; 24% were receiving antihypertensive therapy (HTT) and normal LV geography was seen in 43%. Associations between blood pressure and echocardiographic LV outcomes were similar for systolic, diastolic, and mean arterial pressure as well as pulse pressure. Results for systolic blood pressure (SBP) are reported in detail. Beginning at the SBP determined at age 36, there was an association with higher LVMI at ages 60-64, which was unchanged after adjustment for HTT. SBP at age 53 was independently associated with LVMI. This association was marginally attenuated by adjustment for SBP at ages 60-64. The relationship between LVMI and SBP at 53 years remained after adjustment for BMI, presence of diabetes, smoking, and physical activity status at ages 60-64. Subjects on HTT from age 43 on had higher mean LVMI than those not on treatment after adjusting for SBP at 60-64 years and other covariables. Greater increases in SBP between ages 43 and 53 years and 53 and 60-64 years were significantly related to larger LVMI, whereas rate of change in SBP from ages 36-43 years was only weakly related to LVMI. The strongest relationship between change in SBP and LVMI was for change between ages 43 and 53 years (p = 0.002).
Higher midlife blood pressure and a greater change in SBP in the fifth decade of life is associated with higher LVMI in later life. This association is independent of current blood pressure. Successful treatment of hypertension does not fully reduce the adverse effect of LVMI in later life.
This large-scale longitudinal study, spanning serial blood pressure determination over a 24- to 28-year period, demonstrates the relationship between elevated blood pressure and subsequent development of LV hypertrophy. It should be emphasized that this study population was a relatively homogenous Caucasian population of British subjects, and the observations may not apply to other ethnic groups. The major finding of this study was that elevated blood pressure in midlife predicts the presence of elevated LVMI in later life and that this effect is not fully reduced by hypertensive therapy. Of note, the HTT was with a variety of agents, and whether a single specific agent would have resulted in a different effect is purely conjectural. Another major finding was the apparent age threshold for subsequent development of LV hypertrophy in which individuals with a faster increase in SBP between the ages of 43 and 53 were more likely to have a greater increase in LVMI. If one presumes that increased LVMI with attendant fibrosis is a long-term risk factor for cardiovascular events, this study raises an important issue regarding the timing and nature of treatment of hypertensive patients and supports the rationale for further prospective studies aimed at reversal of LV and myocardial fibrosis. Not addressed in this study was whether the elevated LVMI predisposed the study subjects to an increased risk of cardiovascular events including heart failure and myocardial infarction.
Keywords: Hypertrophy, Left Ventricular, Ethnic Groups, Wales, Antihypertensive Agents, Scotland, Blood Pressure, Risk Factors, Smoking, Body Mass Index, Motor Activity, Blood Pressure Determination, Hypertension, Diabetes Mellitus, England
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