Blood pressure treated aggressively increases heart disease risk
Blood pressure management must be done judiciously with respect for the fact that driving blood pressure too low with medication results in worse outcomes. Is this surprising if we consider that blood pressure can increase to compensate for peripheral resistance (associated with diminished vascular elasticity and sympathetic nervous system dominance that typically occurs with aging) in order to get oxygen into the tissues (perfusion)? A study just published in the journal Diabetes Care adds more to the large body of evidence* that 120/80 should not be the target. The authors investigated specifically the association of blood pressure levels and heart disease risk in diabetic patients:
"Blood pressure control can reduce the risk of coronary heart disease (CHD) among diabetic patients; however, it is not known whether the lowest risk of CHD is among diabetic patients with the lowest blood pressure level."
So they looked into this by examining data for 17,536 African American and 12,618 white diabetic patients, using Cox proportional hazards regression models to gauge the association of blood pressure with CHD risk. They found a U-shaped curve:
"During a mean follow-up of 6.0 years, 7,260 CHD incident cases were identified. The multivariable-adjusted hazard ratios of CHD associated with different levels of systolic/diastolic blood pressure at baseline (<110/65, 110–119/65–69, 120–129/70–80, and 130–139/80–90 mmHg [reference group]; 140–159/90–100; and ≥160/100 mmHg) were 1.73, 1.16, 1.04, 1.00, 1.06, and 1.11 (P trend <0.001), respectively, for African American diabetic patients, and 1.60, 1.27, 1.08, 1.00, 0.95, and 0.99 (P trend<0.001) for white diabetic patients, respectively. A U-shaped association of isolated systolic and diastolic blood pressure at baseline as well as blood pressure during follow-up with CHD risk was observed among both African American and white diabetic patients (all P trend <0.001). The U-shaped association was present in the younger age-group (30–49 years), and this U-shaped association changed to an inverse association in the older age-group (≥60 years)."
In other words, there is a U-shaped curve in patients with type 2 diabetes with rates of coronary heart disease (CHD) increasing at both the lower and upper ends of blood pressure. Moreover, in folks over 60 the association becomes inverse—patients with lower blood pressure had a higher CHD risk across the board.As reported on Medscape Family Medicine, study coauthor Gang Hu, MD, PhD comments...
"We should pay attention not only to the harm of uncontrolled blood pressure but [also to] aggressively controlled blood pressure."
He added...
"My advice for individual clinicians is the idea of 'the lower, the better' should pass away… Patients need individualized or tailored treatment for their hypertension."
While there may be comorbidities associated with the lowest blood pressure, it stands to reason that diminished oxygen delivery to tissues—hypoperfusion—is an important factor. Dr. Hu further comments:
"Low blood pressure might increase cardiovascular risk by the underperfusion of vital organs. Elderly patients with type 2 diabetes represent a population that is highly enriched with underlying coronary artery disease and may be more prone than others to display the harm of underperfusion."
The authors conclude:
"Our study suggests that there is a U-shaped or inverse association between blood pressure and the risk of CHD, and aggressive blood pressure control (blood pressure <120/70 mmHg) is associated with an increased risk of CHD among both African American and white patients with diabetes."
* Those with particular interest in the topic of blood pressure management should see these earlier posts: