- Email: [email protected]
Resting heart rate in relation to blood pressure: Results from the World Health Organization—Cardiovascular Disease and Alimentary Comparison Study
Letters to the Editor [10] Khan IA, Biddle WP, Najeed SA, Abdul-Aziz S, Mehta NJ, Salaria V, Murcek AL, Harris DM. Isolated noncompaction cardiomyopathy presenting with paroxysmal supraventricular tachycardia—case report and literature review. Angiology 2003;54:243–50. [11] Okubo K, Sato Y, Matsumoto N, Kunimasa T, Kasama S, Sano Y, Miki T, Iida K, Saito F, Saito S, Hirayama A. Cardiac resynchronization and cardioverter defibrillation
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therapy in a patient with isolated noncompaction of the ventricular myocardium. Int J Cardiol 2009;136:e66–8. [12] Coats AJ. Ethical authorship and publishing. Int J Cardiol 2009;131:149–50.
0167-5273/$ – see front matter © 2009 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2009.04.031
Resting heart rate in relation to blood pressure: Results from the World Health Organization—Cardiovascular Disease and Alimentary Comparison Study Longjian Liu a,⁎, Shunsaku Mizushima b, Katsumi Ikeda c, Yasuo Nara d, Yukio Yamori e for the CARDIAC Study Group a
Department of Epidemiology and Biostatistics, Drexel University School of Public Health, Philadelphia, Pennsylvania, 19102, USA Department of Public Health, Yokohama City University Graduate School of Medicine, Yokohama, Japan Mukogawa Women's University, Nishinomiya, Japan d School of Pharmacy, Shujitsu University, Okayama, Japan e Institute for World Health Development, Mukogawa Women's University, Nishinomiya 663-8179, Japan b c
a r t i c l e
i n f o
Article history: Received 14 April 2009 Accepted 24 April 2009 Available online 17 May 2009 Keywords: Heart rates Blood pressure CARDIAC study
Epidemiological studies have reported that increased heart rate (HR) is associated with cardiovascular mortality and even noncardiovascular disease [1–4]. However, only in recent years, has interest been aroused by an awareness that the HR–CVD association may be explained by the association between heart rate and blood pressure (BP) [4,5]. Despite these observations, the importance of associations between HR and BP is still poorly recognized in research and clinical practice [5]. Furthermore, few studies that have tested this association applied a sample size big enough from an international cooperative study. The World Health Organization—Cardiovascular Disease and Alimentary Comparison (CARDIAC) Study provides an opportunity with us to examine this association between HR and BP in middle-aged populations [6–10]. The CARDIAC Study, with a multi-center cross-sectional study design, started in mid 1985, and continues at its phase II stage (e.g., MONALISA Study) [6,10]. The CARDIAC Study was designed to examine the association between various dietary markers and BP (“Core study”) and between these factors and cardiovascular disease mortality rates (“Complete study”). We have published a series which reports on dietary biomarkers and BP, and dietary biomarkers in relation to deaths from coronary heart disease and stroke [10–12]. In the present report, we used data from the baseline surveys among 54 population samples of 25 ⁎ Corresponding author. Department of Epidemiology and Biostatistics, Drexel University School of Public Health, 1505 Race Street, 6th FL, Philadelphia, PA 19102, USA. Tel.: +1 215 762 1370; fax: +1 215 762 1174. E-mail address: [email protected] (L. Liu).
countries to examine the association between resting HR and BP, because these measures of interest were obtained consistently with the same blood pressure apparatus in which HR (beats per minute) was recorded automatically [6]. BP was measured using an automated BP measurement system repeated three times in the right arm after 3–5 min rest, with participants sitting. Meanwhile, resting HR was also automatically recorded by the BP machine (Khi machine, VINE Co., Ltd., Tokyo) [6]. The lowest values of the three recorded readings were recorded as the individual participant's BP (mmHg) and resting HR (beats per min, bpm). All data analyses were conducted using SPSS version 15 software (SPSS Inc. Chicago, Illinois, 2006). Age- and BMI-adjusted means of SBP and DBP across quartiles of heart rate groups (b64, 64–71, 72–79 and N=80 bpm) were estimated using Analysis of Covariance. Trends in change for mean SBP and DBP across quartiles of heart rate were tested using linear regression analysis. Finally, we applied a multiple linear regression analysis technique to examine the association between heart rate and blood pressure. To ensure statistical power, we used a combined sample of both genders in the analysis for each center. The multiple regression analyses, however, were adjusted for age, BMI and sex. To further get an average estimate (e.g., a pooled value) of heart rate–BP association, the regression coefficients estimated from 54 centers were averaged, with each centers' coefficients being weighted by the inverse of its variance; this procedure minimized the variance of the pooled coefficient [8]. We repeated the data analyses for the total study sample, and a subsample in which subjects who were under anti-hypertensive medication were excluded because they might have normal blood pressure due to the medications. The present study by using the CARDIAC dataset for publication was approved by the Institutional Review Board of the Institute of Mukogawa Women's University, Nishinomiya, Japan. Table 1 shows the basic characteristics of 8541 (M: 4288, F: 4253) participants aged 48–56 years old by sex in 54 centers of the CARDIAC Study. Males had higher mean systolic and diastolic blood pressure (SBP and DBP) than females (p b 0.01). However, females had higher mean body mass index (BMI), resting heart rate (HR) and prevalence of anti-hypertensive medication use than males (p b 0.01). Participants with hypertension had significantly higher mean (SD) heart rates than those with normal blood pressure in men [73.25 (12.6) bpm versus 70.35 (11.9) bpm, p b 0.001], and in women [76.09
74
Letters to the Editor
Table 1 Characteristics of participants in 54 centers in the WHO-CARDIAC Study.
Continuous variables, mean (SD) Age, year Body mass index, kg/m2 SBP, mmHg DBP, mmHg Heart rates, beat per min Categorical variables, % Body mass index (BMI) b25 kg/m2 25–29 kg/m2 N= 30 kg/m2 Total cholesterol b200 mg/dl 200–239 mg/dl N= 240 mg/dl Anti-hypertensive drug use, % Blood pressure by groupsa Normal BP High normal Hypertension
Males (n = 4288)
Females (n = 4253)
Mean or % (SD)
Mean or % (SD)
p-value
51.89 (1.6) 25.00 (4.0) 126.42 (20.1) 76.99 (13.0) 71.27 (12.2)
51.87 (1.6) 25.29 (4.7) 124.66 (21.5) 74.01 (13.0) 74.20 (12.0)
0.80 b 0.001 b 0.001 b 0.001 b 0.001
52.9 37.3 9.9
53.2 31.4 15.4
R × C χ2, p b 0.01
63.2 25.0 11.8 10.6
59.1 26.3 14.6 13.1
51.0 15.7 33.3
53.1 13.5 33.4
R × C χ2, p b 0.01 b 0.01
R × C χ2, p b 0.05
a : Normal BP: SBP b 130 and DBP b 85 and those without anti-hypertensive medication use. High normal BP: (SBP N =130 and SBP b 140) or (DBPN=85 and DBP b 90).Hypertension: SBP N = 140 or DBP N = 90 or those with anti-hypertension medication use.
(13.4) bpm versus 73.36 (11.3) bpm, p b 0.001]. Means (SD) of heart rates were 74.36 (12.1) bpm in those with BMI N =30 kg/m2, and 70.9 (12.2) bpm in those with BMI b 30 kg/m2 (p b 0.001) in men, and the corresponding values were 75.46 (11.7) bpm and 73.98 (12.1) bpm in women (p b 0.001) respectively. Age- and BMI-adjusted mean SBP and DBP increased with increases in mean heart rates by quintiles for males and females. Multi-level linear regression analysis suggests that an increase in each unit of heart rate (bpm) was associated with 0.27 mmHg increase in SBP, and 0.09 mmHg in DBP in the total study population sample; and 0.203 mmHg increase in SBP, and 0.252 mmHg increase in DBP in the sub-sample in which subjects who were under anti-hypertensive medication were excluded in the analysis. The present study observes that elevated resting heart rates were significantly associated with increases in BP in a sample of more than 8500 participants aged 48–56 years old. Several prospective studies have reported resting heart rate be a risk predictor for certain specific-cause deaths, including CVD and non-CVD deaths including the Framingham Study, the NHANES I Epidemiologic Follow-up Study, the NIPPONDATA80 Study, and others [4,13–16]. The mechanisms by which increased HR increasing the risk of CVD are still largely unknown, finding from our present study suggests that the HR–CVD association may be related to the positive association between heart rate and BP. The present study calls for further research with prospective study designs due to the nature of a crosssectional study design [14]. The notable strength of the study is that the findings are based on a sample of international collaborative study with a standardized study design, including measures of BP and heart rate. These standardizations ensure the validity and reliability of the study. In conclusion, the present study adds new evidence of heart rate– BP association to the scientific literature. It highlights the importance of monitoring changes in heart rates in research and clinical practice. The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology [17].
0167-5273/$ – see front matter © 2009 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2009.04.032
References [1] Fujiura Y, Adachi H, Tsuruta M, Jacobs Jr DR, Hirai Y, Imaizumi T. Heart rate and mortality in a Japanese general population: an 18-year follow-up study. J Clin Epidemiol 2001;54:495–500. [2] Kannel WB, Kannel C, Paffenbarger Jr RS, Cupples LA. Heart rate and cardiovascular mortality: the Framingham Study. Am Heart J 1987;113:1489–94. [3] Mensink GB, Hoffmeister H. The relationship between resting heart rate and allcause, cardiovascular and cancer mortality. Eur Heart J 1997;18:1404–10. [4] Okamura T, Hayakawa T, Kadowaki T, et al. Resting heart rate and cause-specific death in a 16.5-year cohort study of the Japanese general population. Am Heart J 2004;147:1024–32. [5] Palatini P, Dorigatti F, Zaetta V, et al. Heart rate as a predictor of development of sustained hypertension in subjects screened for stage 1 hypertension: the HARVEST Study. J Hypertens 2006;24:1873–80. [6] CARDIAC (Cardiovascular Diseases and Alimentary Comparison) Study Committee. Excerpts from the WHO CARDIAC Study Protocol. J Cardiovasc Pharmacol 1990;16(Suppl 8):S75–7. [7] Yamori Y. WHO CARDIAC Study—Its experimental background and progress report. J UOEH 1989;11:30–8 Suppl. [8] Liu L, Ikeda K, Yamori Y. WHO-CARDIAC Study Group. Inverse relationship between urinary markers of animal protein intake and blood pressure in Chinese: results from the WHO Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study. Int J Epidemiol 2002;31:227–33. [9] Liu L, Liu L, Ding Y, et al. Ethnic and environmental differences in various markers of dietary intake and blood pressure among Chinese Han and three other minority peoples of China: results from the WHO Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study. Hypertens Res 2001;24:315–22. [10] Liu L, Ikeda K, Chen M, et al. Obesity, emerging risk in China: trend of increasing prevalence of obesity and its association with hypertensions and hypercholesterolaemia among the Chinese. Clin Exp Pharmacol Physiol 2004;31(Suppl 2):S8–S10. [11] Yamori Y, Nara Y, Mizushima S, Sawamura M, Horie R. Nutritional factors for stroke and major cardiovascular diseases: international epidemiological comparison of dietary prevention. Health Rep 1994;6:22–7. [12] Mizushima S, Yamori Y, Sawamura M, Nara Y. Ethnicity, environment and saltsensitivity in cardiac study: epidemiological implications for prevention. Clin Exp Pharmacol Physiol 1995;22:S412–6. [13] Kaplan JR, Manuck SB, Clarkson TB. The influence of heart rate on coronary artery atherosclerosis. J Cardiovasc Pharmacol 1987;10(Suppl 2) S100,2; discussion S103. [14] Gillum RF, Makuc DM, Feldman JJ. Pulse rate, coronary heart disease, and death: the NHANES I Epidemiologic Follow-up Study. Am Heart J 1991;121:172–7. [15] Drukteinis JS, Roman MJ, Fabsitz RR, et al. Cardiac and systemic hemodynamic characteristics of hypertension and prehypertension in adolescents and young adults: the Strong Heart Study. Circulation 2007;115:221–7. [16] Franklin SS, Pio JR, Wong ND, et al. Predictors of new-onset diastolic and systolic hypertension: the Framingham Heart Study. Circulation 2005;111:1121–7. [17] Coats AJ. Ethical authorship and publishing. Int J Cardiol 2009;131:149–50.
73
therapy in a patient with isolated noncompaction of the ventricular myocardium. Int J Cardiol 2009;136:e66–8. [12] Coats AJ. Ethical authorship and publishing. Int J Cardiol 2009;131:149–50.
0167-5273/$ – see front matter © 2009 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2009.04.031
Resting heart rate in relation to blood pressure: Results from the World Health Organization—Cardiovascular Disease and Alimentary Comparison Study Longjian Liu a,⁎, Shunsaku Mizushima b, Katsumi Ikeda c, Yasuo Nara d, Yukio Yamori e for the CARDIAC Study Group a
Department of Epidemiology and Biostatistics, Drexel University School of Public Health, Philadelphia, Pennsylvania, 19102, USA Department of Public Health, Yokohama City University Graduate School of Medicine, Yokohama, Japan Mukogawa Women's University, Nishinomiya, Japan d School of Pharmacy, Shujitsu University, Okayama, Japan e Institute for World Health Development, Mukogawa Women's University, Nishinomiya 663-8179, Japan b c
a r t i c l e
i n f o
Article history: Received 14 April 2009 Accepted 24 April 2009 Available online 17 May 2009 Keywords: Heart rates Blood pressure CARDIAC study
Epidemiological studies have reported that increased heart rate (HR) is associated with cardiovascular mortality and even noncardiovascular disease [1–4]. However, only in recent years, has interest been aroused by an awareness that the HR–CVD association may be explained by the association between heart rate and blood pressure (BP) [4,5]. Despite these observations, the importance of associations between HR and BP is still poorly recognized in research and clinical practice [5]. Furthermore, few studies that have tested this association applied a sample size big enough from an international cooperative study. The World Health Organization—Cardiovascular Disease and Alimentary Comparison (CARDIAC) Study provides an opportunity with us to examine this association between HR and BP in middle-aged populations [6–10]. The CARDIAC Study, with a multi-center cross-sectional study design, started in mid 1985, and continues at its phase II stage (e.g., MONALISA Study) [6,10]. The CARDIAC Study was designed to examine the association between various dietary markers and BP (“Core study”) and between these factors and cardiovascular disease mortality rates (“Complete study”). We have published a series which reports on dietary biomarkers and BP, and dietary biomarkers in relation to deaths from coronary heart disease and stroke [10–12]. In the present report, we used data from the baseline surveys among 54 population samples of 25 ⁎ Corresponding author. Department of Epidemiology and Biostatistics, Drexel University School of Public Health, 1505 Race Street, 6th FL, Philadelphia, PA 19102, USA. Tel.: +1 215 762 1370; fax: +1 215 762 1174. E-mail address: [email protected] (L. Liu).
countries to examine the association between resting HR and BP, because these measures of interest were obtained consistently with the same blood pressure apparatus in which HR (beats per minute) was recorded automatically [6]. BP was measured using an automated BP measurement system repeated three times in the right arm after 3–5 min rest, with participants sitting. Meanwhile, resting HR was also automatically recorded by the BP machine (Khi machine, VINE Co., Ltd., Tokyo) [6]. The lowest values of the three recorded readings were recorded as the individual participant's BP (mmHg) and resting HR (beats per min, bpm). All data analyses were conducted using SPSS version 15 software (SPSS Inc. Chicago, Illinois, 2006). Age- and BMI-adjusted means of SBP and DBP across quartiles of heart rate groups (b64, 64–71, 72–79 and N=80 bpm) were estimated using Analysis of Covariance. Trends in change for mean SBP and DBP across quartiles of heart rate were tested using linear regression analysis. Finally, we applied a multiple linear regression analysis technique to examine the association between heart rate and blood pressure. To ensure statistical power, we used a combined sample of both genders in the analysis for each center. The multiple regression analyses, however, were adjusted for age, BMI and sex. To further get an average estimate (e.g., a pooled value) of heart rate–BP association, the regression coefficients estimated from 54 centers were averaged, with each centers' coefficients being weighted by the inverse of its variance; this procedure minimized the variance of the pooled coefficient [8]. We repeated the data analyses for the total study sample, and a subsample in which subjects who were under anti-hypertensive medication were excluded because they might have normal blood pressure due to the medications. The present study by using the CARDIAC dataset for publication was approved by the Institutional Review Board of the Institute of Mukogawa Women's University, Nishinomiya, Japan. Table 1 shows the basic characteristics of 8541 (M: 4288, F: 4253) participants aged 48–56 years old by sex in 54 centers of the CARDIAC Study. Males had higher mean systolic and diastolic blood pressure (SBP and DBP) than females (p b 0.01). However, females had higher mean body mass index (BMI), resting heart rate (HR) and prevalence of anti-hypertensive medication use than males (p b 0.01). Participants with hypertension had significantly higher mean (SD) heart rates than those with normal blood pressure in men [73.25 (12.6) bpm versus 70.35 (11.9) bpm, p b 0.001], and in women [76.09
74
Letters to the Editor
Table 1 Characteristics of participants in 54 centers in the WHO-CARDIAC Study.
Continuous variables, mean (SD) Age, year Body mass index, kg/m2 SBP, mmHg DBP, mmHg Heart rates, beat per min Categorical variables, % Body mass index (BMI) b25 kg/m2 25–29 kg/m2 N= 30 kg/m2 Total cholesterol b200 mg/dl 200–239 mg/dl N= 240 mg/dl Anti-hypertensive drug use, % Blood pressure by groupsa Normal BP High normal Hypertension
Males (n = 4288)
Females (n = 4253)
Mean or % (SD)
Mean or % (SD)
p-value
51.89 (1.6) 25.00 (4.0) 126.42 (20.1) 76.99 (13.0) 71.27 (12.2)
51.87 (1.6) 25.29 (4.7) 124.66 (21.5) 74.01 (13.0) 74.20 (12.0)
0.80 b 0.001 b 0.001 b 0.001 b 0.001
52.9 37.3 9.9
53.2 31.4 15.4
R × C χ2, p b 0.01
63.2 25.0 11.8 10.6
59.1 26.3 14.6 13.1
51.0 15.7 33.3
53.1 13.5 33.4
R × C χ2, p b 0.01 b 0.01
R × C χ2, p b 0.05
a : Normal BP: SBP b 130 and DBP b 85 and those without anti-hypertensive medication use. High normal BP: (SBP N =130 and SBP b 140) or (DBPN=85 and DBP b 90).Hypertension: SBP N = 140 or DBP N = 90 or those with anti-hypertension medication use.
(13.4) bpm versus 73.36 (11.3) bpm, p b 0.001]. Means (SD) of heart rates were 74.36 (12.1) bpm in those with BMI N =30 kg/m2, and 70.9 (12.2) bpm in those with BMI b 30 kg/m2 (p b 0.001) in men, and the corresponding values were 75.46 (11.7) bpm and 73.98 (12.1) bpm in women (p b 0.001) respectively. Age- and BMI-adjusted mean SBP and DBP increased with increases in mean heart rates by quintiles for males and females. Multi-level linear regression analysis suggests that an increase in each unit of heart rate (bpm) was associated with 0.27 mmHg increase in SBP, and 0.09 mmHg in DBP in the total study population sample; and 0.203 mmHg increase in SBP, and 0.252 mmHg increase in DBP in the sub-sample in which subjects who were under anti-hypertensive medication were excluded in the analysis. The present study observes that elevated resting heart rates were significantly associated with increases in BP in a sample of more than 8500 participants aged 48–56 years old. Several prospective studies have reported resting heart rate be a risk predictor for certain specific-cause deaths, including CVD and non-CVD deaths including the Framingham Study, the NHANES I Epidemiologic Follow-up Study, the NIPPONDATA80 Study, and others [4,13–16]. The mechanisms by which increased HR increasing the risk of CVD are still largely unknown, finding from our present study suggests that the HR–CVD association may be related to the positive association between heart rate and BP. The present study calls for further research with prospective study designs due to the nature of a crosssectional study design [14]. The notable strength of the study is that the findings are based on a sample of international collaborative study with a standardized study design, including measures of BP and heart rate. These standardizations ensure the validity and reliability of the study. In conclusion, the present study adds new evidence of heart rate– BP association to the scientific literature. It highlights the importance of monitoring changes in heart rates in research and clinical practice. The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology [17].
0167-5273/$ – see front matter © 2009 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2009.04.032
References [1] Fujiura Y, Adachi H, Tsuruta M, Jacobs Jr DR, Hirai Y, Imaizumi T. Heart rate and mortality in a Japanese general population: an 18-year follow-up study. J Clin Epidemiol 2001;54:495–500. [2] Kannel WB, Kannel C, Paffenbarger Jr RS, Cupples LA. Heart rate and cardiovascular mortality: the Framingham Study. Am Heart J 1987;113:1489–94. [3] Mensink GB, Hoffmeister H. The relationship between resting heart rate and allcause, cardiovascular and cancer mortality. Eur Heart J 1997;18:1404–10. [4] Okamura T, Hayakawa T, Kadowaki T, et al. Resting heart rate and cause-specific death in a 16.5-year cohort study of the Japanese general population. Am Heart J 2004;147:1024–32. [5] Palatini P, Dorigatti F, Zaetta V, et al. Heart rate as a predictor of development of sustained hypertension in subjects screened for stage 1 hypertension: the HARVEST Study. J Hypertens 2006;24:1873–80. [6] CARDIAC (Cardiovascular Diseases and Alimentary Comparison) Study Committee. Excerpts from the WHO CARDIAC Study Protocol. J Cardiovasc Pharmacol 1990;16(Suppl 8):S75–7. [7] Yamori Y. WHO CARDIAC Study—Its experimental background and progress report. J UOEH 1989;11:30–8 Suppl. [8] Liu L, Ikeda K, Yamori Y. WHO-CARDIAC Study Group. Inverse relationship between urinary markers of animal protein intake and blood pressure in Chinese: results from the WHO Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study. Int J Epidemiol 2002;31:227–33. [9] Liu L, Liu L, Ding Y, et al. Ethnic and environmental differences in various markers of dietary intake and blood pressure among Chinese Han and three other minority peoples of China: results from the WHO Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study. Hypertens Res 2001;24:315–22. [10] Liu L, Ikeda K, Chen M, et al. Obesity, emerging risk in China: trend of increasing prevalence of obesity and its association with hypertensions and hypercholesterolaemia among the Chinese. Clin Exp Pharmacol Physiol 2004;31(Suppl 2):S8–S10. [11] Yamori Y, Nara Y, Mizushima S, Sawamura M, Horie R. Nutritional factors for stroke and major cardiovascular diseases: international epidemiological comparison of dietary prevention. Health Rep 1994;6:22–7. [12] Mizushima S, Yamori Y, Sawamura M, Nara Y. Ethnicity, environment and saltsensitivity in cardiac study: epidemiological implications for prevention. Clin Exp Pharmacol Physiol 1995;22:S412–6. [13] Kaplan JR, Manuck SB, Clarkson TB. The influence of heart rate on coronary artery atherosclerosis. J Cardiovasc Pharmacol 1987;10(Suppl 2) S100,2; discussion S103. [14] Gillum RF, Makuc DM, Feldman JJ. Pulse rate, coronary heart disease, and death: the NHANES I Epidemiologic Follow-up Study. Am Heart J 1991;121:172–7. [15] Drukteinis JS, Roman MJ, Fabsitz RR, et al. Cardiac and systemic hemodynamic characteristics of hypertension and prehypertension in adolescents and young adults: the Strong Heart Study. Circulation 2007;115:221–7. [16] Franklin SS, Pio JR, Wong ND, et al. Predictors of new-onset diastolic and systolic hypertension: the Framingham Heart Study. Circulation 2005;111:1121–7. [17] Coats AJ. Ethical authorship and publishing. Int J Cardiol 2009;131:149–50.