Heart Disease: Lowering the Treatment Targets
By Dr. Shafiq Qaadri, MD
Last week, a South Asian patient of mine returned after a five-year absence. The last time I had seen her, I had warned her that she had elevated blood pressure, cholesterol and glucose levels. Now she shared with me that her husband had just died of a stroke at the age of 53. Living through her husband's paralysis and eventual death had brought a message home to her: She realized she needed treatment for her own condition.
I was relieved that she came to me when she did, as new research has caused doctors to re-evaluate acceptable levels for blood pressure, cholesterol and glucose. She required more urgent and extreme treatment than I would have recommended just five years ago.
Emerging evidence from the Framingham Heart Study in Massachusetts, the most expansive and longest-running study of heart-related health issues, indicates that we need to reduce our target levels for all three of these conditions.
Take high blood pressure, which is a cause of major illnesses and can cause death. Although many factors must be considered when assessing a patient -- age, sex, smoking, exercise, family history and obesity -- high blood pressure is generally defined as any reading greater than 140/90 mm Hg. (Blood pressure is measured using the unit millimetres of mercury. The first, higher number refers to the pressure when the heart contracts and pumps blood into the arteries. The lower number is the pressure between beats.) Doctors traditionally use 140/90 as the treatment goal.
But according to the Farmingham study, this limit appears to be too high. Loretta Daniel, assistant professor of cardiology at the University of Toronto, said at a recent hypertension conference: "We must think of cardiac risk as a continuum, a spectrum, not just starting at arbitrary cutoff numbers."
In high risk patients, the new target is below 130/80 mm Hg. Some researchers argue the optimal value should be even lower, below 120/80. These revised levels promise to cause a revolution in how doctors treat high blood pressure.
Cholesterol management is also evolving. Elevated blood cholesterol predisposes one to atherosclerotic plaques and arterial hardening, which can lead to chest pain, leg circulation problems, heart attacks or stroke.
Years ago, the National Cholesterol Education Program (NCEP) told physicians that targeting total cholesterol values was adequate. If a patient had a total cholesterol less than 5.2 mmol/L, (millimoles per litre) he would have a low heart attack risk. Then the NCEP began to subdivide into good and bad cholesterol.
The good stuff, high density lipoprotein, actually helps clear arteries, while low density lipoprotein plugs things up. Physicians were first recommended to use an LDL target below 3.2. Now this has been lowered to 2.0 in high risk patients.
Some researchers call for even more dramatic reductions. Robert Hegele, a professor of biochemistry at the University of Western Ontario and one of Canada's leading geneticists, speculates that the target LDL might be lowered further. That's fantastically low and will likely require stringent lifestyle modifications on the part of patients. They will be encouraged to lower their dietary fat intake, engage in regular aerobic exercise and lower their stress levels.
It will also likely require higher-dose medications and new-generation drugs. The theory is that with a low enough LDL, arterial blockage will not only stop progressing, but even reverse. That's the goal of the emerging discipline of preventive cardiology. Physicians hope that lower cholesterol levels will allow them to perform non-surgical medical bypasses: Clearing clogged passages using powerful drugs that I call "Drano for your arteries."
But doctors are asking themselves: "How low should we go?"
Glucose sugar targets are also falling. Previously, the Canadian Diabetes Association (CDA) said normal glucose levels after eight to 12 hours of fasting should be below 7.8 mmol/L. Some time ago, the number was lowered to 7.0. But the CDA has now revived an old category, "pre-diabetic state" for those with a fasting glucose between 6.0 to 6.9. Without intervention, a pre-diabetic will eventually develop full diabetes and suffer from long-term kidney, eye and nerve complications. And when it comes to heart attack risk, "diabetes puts you at the front of the line," Hegele says.
The Framingham Heart Study reveals that diabetics are in the highest risk category -- a risk equivalent to already having had a heart attack. That demands extreme treatment, including thorough testing, multiple drugs, education and regular follow-up.
All this recalibration to lower treatment thresholds and targets will present a significant challenge for patients, caregivers and the health care system. Achieving the desired results will mean earlier testing and treatment.
With all of this new information, I couldn't help but wonder if my patient's husband's premature stroke could have been prevented. But I will be sure to speak to her about all those optimal numbers at her next appointment.
Dr. Shafiq Qaadri is a Toronto family physician and Continuing Medical Education (CME) lecturer. www.doctorQ.ca
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