Managing High Blood Pressure: The Cardiologist’s Perspective

John J. Ryan, MD, FACC, FAHA
Assistant professor in the Department of Internal Medicine at the University of Utah

Do you treat many patients for hypertension who also have hematologic malignancies?

We definitely do, and obviously, some of that prevalence is due to age. As we age, the risk of developing hypertension increases, and, unfortunately, so does the risk of developing hematologic malignancies.

The common risk factor in many of these circumstances is age.

When and how should the hematologist consult the cardiologist in the management of patients with hypertension?

Because hypertension is so common, it can be difficult to determine the appropriate moment to reach out for a consult or a referral to a cardiologist. High blood pressure also carries an increased risk of cardiovascular consequences such as strokes, heart attacks, and heart failure, among others.

If a hematologist is uncomfortable managing a patient with high blood pressure, he or she should refer to the cardiologist; for instance:

  • if the blood pressure is persistently elevated despite best efforts
  • if there is concern about complications from the high blood pressure, such as damage to the heart
  • if the hematologist is worried about a patient’s risk of stroke, or if the patient has had a stroke in the past

Patients with hematologic malignancies are sometimes referred to the tertiary care centers for their cancer treatments, and, in that setting, the staff may be unfamiliar with the patient’s background and full cardiac history; in that circumstance, again, it’s reasonable to get the cardiologist involved.

Ultimately, when patients are undergoing treatment for a hematologic malignancy, it’s important that the clinician not lose sight of the fact that he or she may have or have previously had high blood pressure.

Does hypertension contribute to a greater risk for blood clots and thrombosis? What is the role of the platelet in this?

Hypertension does increase the risk of having a clinical event, as well as organ damage; many of these effects are mediated through the development of clots.

So, yes, hypertension does contribute to a patient’s thrombotic risk. As hematologists know, most clots are developed through platelet activation; how hypertension interacts with platelet activation is very challenging. There are two general approaches to treating hypertension and its clinical consequences: anti-hypertensive agents (such as beta-blockers, ACE inhibitors, calcium channel blockers) to lower the blood pressure, and antiplatelet agents (such as aspirin) to inhibit platelet aggregation and lower the risk of the associated clinical events.

Ultimately, what we try to do is prevent the clinical consequence of this platelet activation. We can know that platelets are activated, but that activation becomes much more important when the patient has a clinical event (a heart attack, a stroke, etc.). With anti-hypertensive medications, therefore, the goal is to decrease the risk of the clinical consequences of platelet activation.

Are there causes of high blood pressure potentially related to hematologic conditions?

The overproduction of red blood cells and high hematocrit levels associated with polycythemia vera can contribute to systemic hypertension; high hematocrit levels have been found to interfere with the vasodilatory effects of nitric oxide. The treatment of polycythemia, which can involve phlebotomy, can alleviate the systemic hypertension, as well as the physiological consequences of having a high red blood cell count.

Again, I have to stress that the common risk factor is age, and, with the aging population, both hypertension and hematologic malignancies are increasingly more common. Clinicians need to remember that none of this is happening in a vacuum. We need to be cognizant that, when we are caring for a patient and see another issue that we are uncomfortable with, we can ask for help.