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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 8  |  Issue : 2  |  Page : 98-102

Heart rate in patients with or without hypertension: A retrospective study


Department of Medicine, Indira Gandhi Government Medical College and Hospital, Nagpur, Maharashtra, India

Date of Submission17-Jan-2020
Date of Decision26-Jan-2020
Date of Acceptance27-Apr-2020
Date of Web Publication4-Aug-2020

Correspondence Address:
Dr. Shankar G Vasista
Department of Medicine, Indira Gandhi Government Medical College and Hospital, CA Road, Nagpur - 440 018, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/heartindia.heartindia_3_20

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  Abstract 


Introduction: Heart rate (HR) is correlated with peripheral and central blood pressure (BP), which may be a determinant in the development of hypertension (HTN). The objective of this study was to assess the HR in patients with and without HTN and identify the determinants of HR in patients with HTN.
Materials and Methods: In a retrospective analysis of patient data at a single center from central India, HR was Clinic records, with the presence assessed using an electronic pulse recorder as well as using the traditional method of counting radial pulse. A patient with HTN was identified by the presence of BP ≥140/90 mmHg or by their taking antihypertensive medications. HR was compared between patients with and without HTN. Factors associated with HR in patients with HTN were assessed.
Results: In a total of 1020 patients' data included in the study, 81.5% had HTN and 18.5% were nonhypertensive. The mean HR was significantly higher in patients with HTN than in controls (78.0 ± 13.0 vs. 75.7 ± 10.3 beats per min [bpm], P = 0.033). Furthermore, the proportion of patients with HR ≥≥80 bpm was significantly higher in patients with HTN (43.9% vs. 24.4%, P = 0.017). In patients with HTN, the mean HR was significantly higher in those who had diabetes (P = 0.002). A significantly higher percentage of patients who had HR 80 bpm or more were females (P = 0.015), had diabetes (P = 0.002) and uncontrolled BP (P = 0.036), and were receiving thiazide diuretics (P = 0.001).
Conclusion: HR is significantly higher in patients with HTN than nonhypertensive controls in the central Indian population. Prospective studies are necessary to assess the impact of various factors on HR and also the role of HR in the development of incident HTN and adverse cardiovascular outcomes in patients with HTN.

Keywords: Beta-blockers, blood pressure, heart rate, hypertension, India


How to cite this article:
Vasista SG. Heart rate in patients with or without hypertension: A retrospective study. Heart India 2020;8:98-102

How to cite this URL:
Vasista SG. Heart rate in patients with or without hypertension: A retrospective study. Heart India [serial online] 2020 [cited 2020 Oct 31];8:98-102. Available from: https://www.heartindia.net/text.asp?2020/8/2/98/291358




  Introduction Top


Heart rate (HR) has a linear association with blood pressure (BP).[1] The HR in patients with hypertension (HTN) is higher compared to the normotensive population.[2],[3] Resting HR in patients with HTN has prognostic importance. In HTN, increments of 10 beats per min (bpm) are associated with an increased risk of adverse cardiovascular (CV) outcomes and mortality.[4],[5] HR is, thus, identified as an important CV disease risk factor, which should be included in the assessment of patients with HTN, by expert panelists from the European Society of Hypertension.[6] Among many antihypertensive therapies, beta-blockers (BBs) are effective in reducing the HR. Experts have advised that newer generation BB such as nebivolol should be preferred to older ones (e.g., atenolol) as they effectively reduce the peripheral as well as central BP.[7],[8] Although the target HR in patients with HTN remains unknown, a threshold of <70 bpm or reduction of at least 10 bpm from baseline on BB treatment has been advised.[7] However, it remains unclear whether targeting HR reduction in HTN improves CV outcomes. Although the studies from India have reported HR reduction with BB treatment in patients with HTN,[8],[9] its relationship with HTN in comparison to normotensive individuals and with control of HTN has not been studied in the Indian setting. Therefore, we planned this study to assess the association of HR with BP level in patients with HTN and normotensive individuals as well as with control of HTN. We also explored the relationship of HR with body mass index (BMI) in patients with HTN.


  Materials and Methods Top


Study setting

This study was conducted at a private medical clinic from an urban tier 2 city from central India. This clinic provides medicine specialty services to urban, semi-urban, and rural populations from around the locality.

Study design

This was a single-center, retrospective, observational study. The patient database at our center was screened for the inclusion of hypertensive patients and control nonhypertensive patients.

Study population

The file record database was screened to identify patients with or without HTN. From these records, data were entered into Microsoft Excel. The inclusion criteria were age of 18 years and above, either gender, and diagnosed HTN (defined by whether the patient was receiving antihypertensive treatment or BP was ≥140/90 mmHg). The exclusion criteria were pregnant and lactating females, patients with heart failure or major coronary artery disease, patients with stroke, patients who had terminal illness, patients with arrhythmias, patients who had any major surgery within the past 3 months from the date of their examination at our center, and those who were on hemodialysis.

Data collection

From their medical records, patients' data were transferred to an Excel Spreadsheet. Data points included age, gender, weight, BMI, current BP levels, HR, presence of comorbidities such as HTN and type 2 diabetes (T2D), and treatments received for the management of HTN such as BB, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers (ARBs), calcium channel blockers, thiazide diuretics, and other antihypertensive medications. At our center, weight was measured on an electronic weighing machine (Omron-Digital weight scale) having a weight range from 2 kg to 180 kg. Height is measured using a height measuring caliper. BMI was calculated using the standard formula (weight [Kg]/height [m2]).

Before the measurement of the HR and BP, patients were rested for 5–10 min in the outpatient waiting area. HR was measured using a pulse oximeter (EasyCare-pulse oximeter device (Sunway Health Care, Chennai, India)). The index finger of the patients was placed between the beam recorder of the pulse oximeter. After switching the pulse oximeter on, reading of the HR was noted after the finger was in place for at least 1 min. BP was measured in the sitting position with arm supported. An electronic BP recording machine (Omron – HEM 8712, Omron Healthcare Company Ltd. Kyoto, Japan) was used to measure BP. As a standard protocol followed at our clinic, two BP readings 1 min apart were taken and averaged to derive final BP levels in all patients. Among the patients who were being treated with antihypertensive agents, those with BP levels <140/90 mmHg were considered as controlled HTN, and any patient with BP levels above this threshold were labeled as uncontrolled HTN.

Statistical analysis

Data were entered in to the Microsoft Excel spreadsheet and were analyzed with the same. Categorical variables were presented as frequency and percentages. Continuous data were presented as mean and standard deviation. Chi-square test/Fischer exact test was used to determine statistical significance in categorical variables, and Student's t-test was used to determine statistical significance in continuous variables. Correlation of continuous variables was assessed by Pearson correlation coefficient P < 0.05 was considered statistically significant in all comparisons.


  Results Top


Baseline characteristics

In this study, a total of 1020 participants were included. Of these, 81.5% (n = 831) had HTN and 18.5% (n = 189) were nonhypertensive individuals [Figure 1]. The baseline characteristics of the two groups of patients are outlined in [Table 1]. The mean age was 56.7 ± 11.6 years in patients with HTN, and the majority (46.7%) belonged to the age group of 50–65 years. The proportion of females was higher in both groups than males. A greater proportion of patients with HTN belonged to higher BMI quintiles than nonhypertensive patients. About 72.4% of patients with HTN had their BP in control (<140/90 mmHg). Among the two groups, a greater proportion of the patients with HTN had diabetes compared to nonhypertensive patients (48% vs. 11.1%). ARBs (91.1%) were most frequently prescribed antihypertensive therapy, followed by thiazide diuretics (48.4%). BBs were prescribed in 6.5% of the patients with HTN.
Figure 1: Distribution of patients in two groups

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Table 1: Baseline characteristics (n=1020)

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HR in two groups

The mean resting HR was significantly higher in patients with HTN than normotensive patients (78.0 ± 13.0 vs. 75.7 ± 10.3 bpm, respectively, P = 0.033). Furthermore, the proportion of patients with HR ≥80 bpm was higher in the HTN group (43.9% vs. 24.4%, P = 0.017), as shown in [Table 2].
Table 2: Heart rate distribution

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Correlation ofHR with blood pressure

A significant positive correlation of HR with systolic BP (SBP) (r = 0.095, P = 0.006) and diastolic BP (DBP) (r = 0.150, P < 0.001) was seen in patients with HTN. In the nonhypertensive group, a significant correlation was seen only with DBP (r = 0.261, P < 0.001), as shown in [Table 3].
Table 3: Correlation of heart rate with blood pressure

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Factors affecting HR in patients with hypertension

The factors that could affect the HR in HTN are summarized in [Table 4]. We observed that mean HR was significantly higher in patients with coexisting diabetes (79.4 ± 13.1 vs. 76.6 ± 12.7 bpm, P = 0.002). The mean HR was nonsignificantly higher in females than males (78.6 ± 12.4 vs. 77.1 ± 13.5, P = 0.084) and patients with uncontrolled HTN compared to controlled HTN (79.3 ± 13.3 vs. 77.4 ± 12.8 bpm, P = 0.056). Among patients with HTN, 365 had HR ≥80 bpm. The distribution of such raised HR was significantly higher in females (57% vs. 43%, P = 0.015), patients with diabetes (54% vs. 46%, P = 0.002), patients with uncontrolled HTN (68.8% vs. 31.2%, P = 0.036), and patients being treated with thiazide diuretics (55.1% vs. 44.9%, P = 0.001). The association of other factors as age, BMI, and other antihypertensive therapies was nonsignificant [Table 4].
Table 4: Assessment of factors affecting heart rate distribution in patients with hypertension

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  Discussion Top


In this study, we observed that mean HR was significantly higher in patients with HTN than normotensive patients. Furthermore, a greater proportion of patients with HTN had HR ≥80 bpm than normotensive individuals (43.9% vs. 24.4%, P = 0.017). This is in clear alignment with previous reports which suggest that HR is higher in patients with HTN than normotensive individuals.[1],[2],[3] A survey from India in 18–55-year-old patients with HTN reported the mean resting HR of 82.79 ± 10.41 bpm.[10] Furthermore, resting HR has been identified as a predictor of incident HTN. A study from China reported that each 10 bpm rise in HR was associated with an 8% increase in incident HTN over 3.5 years of follow-up.[11] Another study reports the association of HR variability with development of HTN in men.[12] It is well established that HR has a linear association with BP. We also observed a significant positive correlation of HR with both SBP and DBP. BEAT survey from India also reported a significant positive correlation of HR with both SBP (r = 0.247, P < 0.01) and DBP (r = 0.219, P < 0.01).[10] This evidence suggests that HR is an important predictor of HTN and patients with rising HR, especially those with >80 bpm should be screened and followed up for incident HTN. The importance of such observation lies in the fact that a rise in HR is also associated with an increased risk of adverse CV events. Findings from an analysis of data in VALUE trial show that a rise of HR by 10 bpm was associated with an increased risk of composite cardiac outcome (Hazard ratio 1.16). Further, it was associated with a significantly higher risk of individual CV events such as heart failure (Hazard ratio: 1.24), sudden cardiac death (Hazard ratio: 1.18), myocardial infarction (Hazard ratio: 1.10), stroke (Hazard ratio: 1.09), and all-cause death (Hazard ratio 1.19).[13] Similarly, an analysis of life study data suggested a 25% increase in the risk of CV deaths and a 27% higher risk of all-cause deaths with each increment in HR by 10 bpm.[14] This suggests that it is important to look closely at HR of patients with HTN which can be an easy and bedside predictor for CV events.

There could be multiple deciding factors for the change in HR in patients with HTN. We observed that the mean HR was significantly higher in patients with diabetes, whereas HR ≥80 bpm was seen in a significantly higher proportion of females, patients with diabetes, uncontrolled BP (>140/90 mmHg), and those receiving thiazide diuretics in treatment. Diabetes is a common accompaniment of HTN. A study from Korea reported that resting HR >80 bpm was associated with significantly higher SBP, DBP, and glucose compared with resting HR <69 bpm. Further, resting HR >80 bpm was associated with 2.76 and 1.27 times higher odds of T2D and HTN compared with those with resting HR <69 bpm.[15] Besides coexistence of diabetes, uncontrolled HTN was also associated with HR ≥80 bpm. This finding has important prognostic implications. In an analysis of VALUE study data, the highest HR quintiles had significantly higher rates of composite endpoint in both controlled (+53%, P < 0.0001) and uncontrolled (+34%, P < 0.002) BP groups. Furthermore, the lower four quintiles combined with uncontrolled BP had a greater risk of incident composite endpoint (P = 0.0035).[13] Although we did not identify a significant association of HR with BMI, evidence suggests a longitudinal association between increased HR, obesity, and metabolic abnormalities. This probably reflects persistent sympathetic stimulation which can favor weight gain. Downregulation of adrenoceptor-mediated thermogenic responses may be the mechanism underlying an elevated sympathetic tone.[5] The finding of a higher proportion of patients receiving thiazide diuretics having HR above 80 bpm is probably a chance finding as the mean HR did not differ whether patients received the thiazide diuretics or not. Furthermore, thiazide diuretics were used in combination with other antihypertensives rather than as monotherapy. It is interesting to note that treatment with BBs had no significant effect on HR; however, this should be considered with caution as the duration BB therapy is not known, and the sample of patients treated with BB is very small. BBs, especially newer, selective beta-1 blockers are advised for the treatment of elevated HR in symptomatic patients with HTN.


  Conclusion Top


In this study, we observed that patients with HTN had significantly higher resting HR. A HR in patients with HTN was seen to be associated with female gender, presence of diabetes, and uncontrolled BP. Therefore, it is advised that HR should be evaluated carefully in patients with HTN as well in nonhypertensive individuals as HR >80 bmp has been observed to be associated with higher risk of incident HTN. Further studies are necessary to assess the impact of different therapies on HR in HTN. Furthermore, outcome studies in the Indian population are warranted to consider HR as one of the potential treatment targets in patients with HTN.

Acknowledgments

The author would like to thank Dr. Vijay Katekhaye for his assistance in drafting and reviewing the manuscript.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Ethical Approval

The study was approved by the local institutional ethical committee and was conducted according to the ethical principles of Declaration of Helsinki and applicable local regulations.



 
  References Top

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Dalal J, Dasbiswas A, Sathyamurthy I, Maddury SR, Kerkar P, Bansal S, et al. Heart rate in hypertension: Review and expert opinion. Int J Hypertens 2019;2019. Article ID: 2087064.  Back to cited text no. 7
    
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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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