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Anot uncommon situation in clinical practice is ayoung patient who presents with a high dias-

tolic pressure and a normal systolic reading, such as135/95 mm Hg, or isolated diastolic hypertension.There is a dilemma here: should the patient be treat-ed or not? Traditionally, diastolic pressure has beenregarded as the most important of the three measuresof pressure (the others being systolic and pulse pres-sure), but recent attention has been focused on theother two, particularly with the recent trials showingthe benefits of treating isolated systolic hypertension,and a flurry of papers suggesting that pulse pressureis the most important risk factor in older patients.

The reasons for the focus on diastolic pressureare largely historical. The first major treatmenttrial, the Veterans Administration study1 conductedby Dr. Ed Fries in the 1960s, used a high diastolicpressure as the main entry criterion; other similartrials have followed suit. One of the largest trialsever conducted, the Hypertension OptimalTreatment (HOT) study,2 attempted to resolve theJ-curve dilemma by titrating patients’ diastolic pres-sures to three levels, 85–90 mm Hg, 80–85 mm Hg,and <80 mm Hg. Even today, a high diastolic pres-sure is the primary requirement for reimbursementfor antihypertensive medications in Finland.3

An analysis of 1560 participants in a worksitehypertension control program4 categorized them as

having either isolated diastolic hypertension (systolic<160 mm Hg and diastolic >90 mm Hg) or com-bined hypertension (systolic >160 mm Hg and dias-tolic >90 mm Hg). Over a 4.5 year follow-up period,there were 24 cases of myocardial infarction, givinga rate of 3.9 per 1000 patient-years. This was higherin the patients with combined hypertension than inpatients with isolated diastolic hypertension (5.2 vs.2.2 per 1000 patient-years) but was zero in the sub-group of patients with high diastolic pressures andsystolic pressures <140 mm Hg.

One of the most illuminating studies is aprospective analysis of 3267 initially healthyFinnish men who were originally evaluated at age30–45 and were followed for up to 32 years.3

They were divided into four groups: normoten-sives (systolic <160 mm Hg and diastolic <90 mmHg), combined hypertension (systolic >160 mmHg and diastolic >90 mm Hg), isolated systolichypertension (systolic >160 mm Hg and diastolic<90 mm Hg), and isolated diastolic hypertension(systolic <160 mm Hg and diastolic >90 mm Hg).The last group was subdivided according towhether the systolic was <140 mm Hg or between140 and 160 mm Hg. Not surprisingly, in this rel-atively young group there were very few with iso-lated systolic hypertension (17 men), but therewas a substantial number (346, or more than 10%of the total) of men with isolated diastolic hyper-tension, where the systolic pressure was <140 mmHg. With the normotensives as the referencegroup, the mortality was increased nearly three-fold in the combined hypertensives (relative risk[RR], 2.71) and in the group with diastolic hyper-tension and systolic pressure between 140 and160 mm Hg (RR, 1.39) but not in the group withisolated diastolic hypertension defined by a sys-tolic pressure <140 mm Hg.

Isolated Diastolic Hypertension

Thomas G. Pickering, MD, DPhil

From the Behavioral, Cardiovascular Health, andHypertension Program, Columbia University College ofPhysicians and Surgeons, New York, NYAddress for correspondence:Thomas G. Pickering, MD, DPhil, Columbia UniversityCollege of Physicians and Surgeons, 630 West 168th Street, New York, NY 10032

E f f e c t s o f S t r e s s a n d B e h a v i o r a l I n t e r v e n t i o n s i n H y p e r t e n s i o nT h o m a s G . P i c k e r i n g , M D , D P h i l , S e c t i o n E d i t o r

www.lejacq.com ID: 2840

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Another study5 (the Japanese Ohasama study)has reported the same finding using home moni-toring. This is of particular interest, since theremight be systematic errors in reporting diastolicpressure with home monitors, all of which operateon the oscillometric method. Home readings wereobtained in 1913 subjects aged 40 or older (aver-age 61 years) who were followed for 8 years. Thecutoff points for the different groups (137 mm Hgfor systolic and 84 mm Hg for diastolic pressure)were lower than used in studies based on clinicmeasurements because these were the numbersabove which cardiovascular risk started toincrease, and it is well recognized that home read-ings tend to be lower than clinic readings. The car-diovascular event rate during the follow-up periodwas the same in the normotensives (0.33 deathsper 100 person-years) and those with isolated dias-tolic hypertension (i.e., systolic pressure <137 mmHg and diastolic >84 mm Hg), where the event ratewas 0.26. Significantly higher rates were recordedin subjects with combined hypertension (1.11) orisolated systolic hypertension (2.04).

A study of the Honolulu Heart Program fol-lowed 8006 men for 20 years.6 Isolated diastolichypertension (IDH) was defined as a systolic pres-sure <160 mm Hg, and a diastolic pressure >90mm Hg. For men aged 45–54 years, the relativerisks of stroke associated with IDH compared withnonhypertensive subjects was 1.4, whereas for menwith isolated systolic hypertension or combinedhypertension the relative risks were 4.8 and 4.3.

Thus, the consensus from these four studiesthat looked at the prognosis of IDH is that if thesystolic is <140 mm Hg, a high diastolic pressureis not associated with an adverse prognosis.

In some subjects with IDH, the high diastolicpressure may be artifactual. Some years ago wedescribed a method of measuring blood pressurenoninvasively using a high fidelity transducerinstead of a stethoscope (wideband external pulserecording), which records the low frequency signalsas well as the higher frequency components that areaudible as the Korotkoff sounds.7 By visual inspec-tion of the traces recorded during cuff deflation, avery accurate estimation of the true systolic anddiastolic pressures can be obtained. We found thatthis method gave a closer agreement with intra-arte-rial pressure than the Korotkoff sound method.When we looked at patients with IDH (systolic<140 and diastolic >90), we found that the diastolicpressure recorded by the conventional auscultatorytechnique was on average 7 mm Hg higher than thevalue recorded by the wideband method.8 This dif-

ference was only 3 mm Hg in patients with com-bined hypertension and zero in normotensives.Thus, it appeared that a substantial number ofpatients with IDH might be misclassified by the con-ventional method of blood pressure measurement.

How do these findings relate to other epidemio-logical studies, which have specifically compared theprognostic significance of systolic and diastolic pres-sures? A recent analysis of the Framingham HeartStudy data looked at the ability of systolic and dias-tolic pressure to predict coronary heart disease as afunction of age.9 In subjects younger than 50 years ofage, diastolic pressure was significantly better thansystolic pressure, whereas systolic pressure was bet-ter over the age of 50. However, when the data wereanalyzed in five age groups, it was only the youngestquintile (younger than 40) where this difference wassignificant. In addition, the method of analysis mayhave led to a bias favoring diastolic pressure becausethe hazard ratios were calculated for a 10 mm Hgchange in each blood pressure component. A changeof diastolic pressure of 10 mm Hg would in real lifebe associated with a change of systolic pressure thatwould be considerably more than 10 mm Hg, so itwould be more appropriate to look at percentagechanges rather than an absolute value. A very similaranalysis was performed in the Physicians’ HealthStudy,10 which found that both systolic and diastolicpressure predicted outcomes in the two youngest agegroups (under 50 and 50–59), but it too calculatedthe hazard ratios for a 10 mm Hg change of bothsystolic and diastolic pressure. Interestingly, the con-fidence intervals were much wider for diastolic thansystolic pressure, suggesting a lack of precision in themeasurement. Nevertheless, the authors concludedthat systolic pressure should be used to predict riskeven in men younger than 60. Another analysis ofthe Physicians’ Health Study and the Women’sHealth Initiative developed risk equation models forpredicting clinical outcomes using both systolic anddiastolic pressures. It concluded that in men, bothsystolic and diastolic pressures predicted risk, but inwomen only systolic pressure was important.11

The reconciliation of these analyses with theprospective studies of IDH is more difficult.Unfortunately for the present discussion, none ofthe studies quoted above looked at the individualswith IDH. The only one to find any superiority fordiastolic pressure was the Framingham study,where it applied only to subjects under the age of40. Therefore, it would seem reasonable not toprescribe antihypertensive treatment for patientswho present with a high diastolic pressure and asystolic pressure <140 mm Hg at the present time.

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This would be consistent with a set of simpleguidelines for primary health care published bySever12 in 1999, which included four rules. RuleOne was “abandon diastolic pressure measurementand rely on systolic blood pressure values for deci-sions on treatment thresholds and goals.” Thisstatement may seem like heresy, but in medicine, asin other fields of human belief and endeavor,today’s heresy may be tomorrow’s dogma.

REFERENCES1 Veterans Administration Cooperative Study Group on

Antihypertensive Agents. Effects of treatment on morbidityin hypertension. JAMA. 1967;202:116–122.

2 Hansson L, Zanchetti A, Carruthers SG, et al. Effects ofintensive blood-pressure lowering and low-dose aspirin inpatients with hypertension: principal results of theHypertension Optimal Treatment (HOT) randomised trial.HOT Study Group. Lancet. 1998;351(9118):1755–1762.

3 Strandberg TE, Salomaa VV, Vanhanen HT, et al. Isolateddiastolic hypertension, pulse pressure, and mean arterialpressure as predictors of mortality during a follow-up of upto 32 years. J Hypertens. 2002;20(3):399–404.

4 Fang J, Madhavan S, Cohen H, et al. Isolated diastolic hyper-tension. A favorable finding among young and middle-aged

hypertensive subjects. Hypertension. 1995;26(3):377–382.5 Hozawa A, Ohkubo T, Nagai K, et al. Prognosis of isolated

systolic and isolated diastolic hypertension as assessed byself-measurement of blood pressure at home: the Ohasamastudy. Arch Intern Med. 2000;160(21):3301–3306.

6 Petrovitch H, Curb JD, Bloom-Marcus E. Isolated systolichypertension and risk of stroke in Japanese-American men.Stroke. 1995;26(1):25–29.

7 Blank SG, West JE, Muller FB, et al. Wideband externalpulse recording during cuff deflation: a new technique forevaluation of the arterial pressure pulse and measurementof blood pressure. Circulation. 1988;77(6):1297–1305.

8 Blank SG, Mann SJ, James GD, et al. Isolated elevation ofdiastolic blood pressure. Real or artifactual? Hypertension.1995;26(3):383–389.

9 Franklin SS, Larson MG, Khan SA, et al. Does the relationof blood pressure to coronary heart disease risk changewith aging? The Framingham Heart Study. Circulation.2001;103(9):1245–1249.

10 Sesso HD, Stampfer MJ, Rosner B, et al. Systolic and dias-tolic blood pressure, pulse pressure, and mean arterial pres-sure as predictors of cardiovascular disease risk in men.Hypertension. 2000;36(5):801–807.

11 Glynn RJ, L’Italien GJ, Sesso HD, et al. Development of pre-dictive models for long-term cardiovascular risk associatedwith systolic and diastolic blood pressure. Hypertension.2002;39(1):105–110.

12 Sever PS. Simple blood pressure guidelines for primaryhealth care. J Hum Hypertens. 1999;13(11):725–727.