Prehypertension and Cardiovascular Morbidity

I would like to comment on the article by Liszka, etal, (1) and the accompanying editorial by Green (2) concerning prehypertension and its effect on morbidity and mortality. My comments are based on my own study of my patients over the 4 November 1974-4 November 2003 time frame. (3-5) My study is called The Bowling Green Study (BGS) of the Primary and Secondary Prevention of Atherothombotic Disease (ATD). Over the 29-year time frame, 1009 patients developed some form of ATD, such as acute myocardial infarction, acute brain infarction, abdominal aortic aneurysm, etc. Blood pressures are available for all 1009 patients. 539 patients are males; 470 patients are females.

Examining the systolic blood pressure data, one finds that 48% of males and 47% of females had hypertension based on systolic blood pressure (SBP)> 140 HG. 39% of males and 35.7% of females had pre-hypertension (SBP: 120-138 mostly). 13% of males and 19% of females had normal blood pressure (SBP<118).

Of course, other risk factor data is available for these patients. Cigarette-smoking data is present in virtually all of these patients. Lipid data is present in 71% of these patients. Taken together, cigarette smoking, dyslipidemia, and hypertension are the main risk factors for ATD. (5)

The lipid risk factor that I use is the cholesterol retention fraction (CRF, or [LDL-HDL]/LDL). (3-5) The CRF exceeds the ability of LDL-cholesterol by itself to predict ATD. (6) The CRF is abnormal at levels > 0.70, of at any level if LDL-cholesterol >170 mg/dl. This latter scenario holds because HDL-cholesterol is unable to compensate for unlimited LDL-cholesterol and this effect begins when LDL-cholesterol > 170 mg/dl. (3-5) The cholesterol threshold (CThr) is exceeded if CRF> 0.70 and/or LDL>170 mg/dl. Cigarette smoking is the chief risk factor for ATD. (7) Cigarette smoking can cause ATD events in the absence of CThr abnormalities. Hypertension has similar properties but mainly affects older ATD patients. In ATD, diabetes tracks with SBP. (8)

Turning to the subject of prehypertension, in my practice, only 5% of male ATD patients and 21% of female ATD patients with prehypertension could not have been predicted by CThr and/or cigarette smoking status. Those males who were not predicted by CThr and/or cigarette smoking status, yet had prehypertension, had an average of ATD onset of 80 years, whereas their female counterparts had an average age of ATD onset of 74 years. In the author's opinion, this difference is due to passive smoking. In the BGS, it is rarely is ever found that a never-smoking male is married to a current-smoking female. On the other hand, it is common for a never-smoking female to be married to a current-smoking male. Hence, a male who is classed as a never-smoker is rarely exposed to cigarette smoke, whereas the same cannot be said for females. Passive smoking is a known risk factor for ATD. (8) Diabetes in the absence of the major three risk factors, may also be operative here.

This is not to imply that SBP had no role in ATD. The role of SBP, however, is subservient to that of CThr or cigarette-smoking status. Indeed, ATD in younger patients is characterized by more marked abnormalities of CThr and/or cigarette-smoking whereas ATD in older patients is characterized by milder abnormalities of CThr, a past history of cigarette smoking, and diabetic hypertension. (8).

In other words, the concept of prehypertension is at best unnecessary in the prediction of ATD. At worst, the concept of prehypertension diverts attention away from the major causes of early-onset ATD: CThr abnormalities and cigarette-smoking.

Sincerely,

William E. Feeman Jr. M.D.

References:

1. Liska, Heather. Prehypertension and Cardiovascular Morbidity. Annals of Family Medicine. Vol. 3;No.4. July/August 2005. 294-299. 2. Green, Lee. Prehypertension, Patient Outcomes, and the Knowledge Base of Family Medicine. Annals of Family Medicine. Vol. 3; No. 4. July/August 2005. 292-293. 3. Feeman, W.E. Jr. The Bowling Green Study of the Primary and Seconday Prevention of Atheroschlerosis: Descriptive Analysis, Findings, Applications, and Conclusions. Ohio J. Sci. 92(5):153-181. 4. Feeman W.E. Jr. The Bowling Green Study of the Primary and Secondary Prevention of Atherochlerotic Disease: Update 1991-1993. Ohio J. Sci. 94(4): 105-112. 5. Feeman W.E. Jr. Prediction of the Population at Risk of Atherothrombotic Disease. Experimental and Clinical Cardiology. Winter 2004. 9:(4); 235-241l 6. Data presented at the 2002 Annual Scientific Assembly of the American Academy of Family Physicians in San Diego. 7. Feeman W.E. Jr. The Role of Cigarette Smoking in Atherothromboic Disease: An Epidemiologic Analysis. J. Cardio Risk. 1999; 6:333- 335. 8. Data presented at the Annual Heart Association Second International Conference on Heart Attacks and Strokes in Women in Orlando.

Competing interests:   None declared