Gender difference of blood pressure variables on ambulatory blood pressure monitoring following percutaneous transluminal coronary angioplasty and 1-year outcomes

Maddury Jyotsna; D Malleswara Rao; Gopikrishna Kenchi; Sudhakar Kanumuri; Shravan Kumar Ch; Rama Kishore Yalampati; C Bharat Kumar Goud; Suresh Yerra; Indrani Garre

doi:10.4103/ACCJ.ACCJ_6_19

ORIGINAL ARTICLE

Year : 2019 | Volume : 1 | Issue : 1 | Page : 2-7

Gender difference of blood pressure variables on ambulatory blood pressure monitoring following percutaneous transluminal coronary angioplasty and 1-year outcomes

Maddury Jyotsna¹, D Malleswara Rao², Gopikrishna Kenchi¹, Sudhakar Kanumuri¹, Shravan Kumar Ch¹, Rama Kishore Yalampati¹, C Bharat Kumar Goud¹, Suresh Yerra¹, Indrani Garre¹
¹ Department of Cardiology, Nizam's Institute of Medical Sciences, Punjagutta, Hyderabad, India
² Consultant Cardiologist, Medicover Hospitals Secretariat (Formerly MaxCure Hospitals) Sarovar Complex, Saifabad, Khairtabad, Secunderabad, Telangana, India

Date of Submission	30-Aug-2019
Date of Decision	31-Oct-2019
Date of Acceptance	09-Nov-2019
Date of Web Publication	13-Dec-2019

Correspondence Address:
Dr. Maddury Jyotsna
Department of Cardiology, Nizam's Institute of Medical Sciences, Hyderabad, Telangana
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ACCJ.ACCJ_6_19

Abstract

Background and Aim: Lack of fall in nocturnal blood pressure (BP) is an independent predictor of poor prognosis. This study determined the prognostic value of BP variables by 24-h ambulatory BP monitoring (ABPM) and associated gender differences after percutaneous transluminal coronary angioplasty (PTCA). Methods: A total of 58 patients underwent PTCA who were subjected to 24-h ABPM and followed for 1-year. Results: All demographic and clinical parameters (female: 10; mean age: 59.4 years), including ABP parameters, were comparable between genders, except smoking and alcoholism. Among nondippers (n = 33), 8 (24.2%) were females, 25 (75.8%) males, 30 (90.9%) diabetes mellitus (DM), 32 (97.0%) hypertension, and had mean diastolic BP (DBP): 86.15 ± 6.31 mmHg, pulse pressure (PP): 55.85 ± 10.09 mmHg, and pulse-wave velocity (PWV): 6.21 ± 01.87 m/s. Most females were nondippers (8 [24.2%]). Nondippers were older in age (P < 0.02) with higher PP (P < 0.001), DBP, and mean BP (MBP). Ejection fraction, presence of coronary artery disease (CAD) or DM, and PWV were comparable between both groups. At 1-year follow-up, one out of two symptomatic patients died, and the other developed chronic stable angina. The major adverse cardiac event rate was 1.7% (1/58). Each left ventricular dysfunction was deteriorated, and contrast-induced nephropathy was seen in three patients. Conclusion: Immediately after PTCA, females were more nondippers than males. Overall, nondippers had higher DBP, MBP, and PP. Nocturnal dipping was not influenced by the presence of DM or CAD. At 1-year follow-up, combined clinical and laboratory events were comparable.

Keywords: Ambulatory blood pressure monitoring, coronary artery disease, percutaneous transluminal coronary angioplasty

How to cite this article:
Jyotsna M, Rao D M, Kenchi G, Kanumuri S, Ch SK, Yalampati RK, Kumar Goud C B, Yerra S, Garre I. Gender difference of blood pressure variables on ambulatory blood pressure monitoring following percutaneous transluminal coronary angioplasty and 1-year outcomes. Ann Clin Cardiol 2019;1:2-7

How to cite this URL:
Jyotsna M, Rao D M, Kenchi G, Kanumuri S, Ch SK, Yalampati RK, Kumar Goud C B, Yerra S, Garre I. Gender difference of blood pressure variables on ambulatory blood pressure monitoring following percutaneous transluminal coronary angioplasty and 1-year outcomes. Ann Clin Cardiol [serial online] 2019 [cited 2023 Mar 26];1:2-7. Available from: http://www.onlineacc.org/text.asp?2019/1/1/2/273003

Introduction

Ambulatory blood pressure monitoring (ABPM) is a useful cost-effective, diagnostic, and prognostic tool that enables the collection of blood pressure (BP) readings several times an hour across a 24-h period.^[1] It is the gold standard for detection of hypertension, including white-coat hypertension, masked hypertension, and nocturnal hypertension.^[2] According to the European Society of Hypertension Practice Guidelines, a 24-h ABP >130/80 mmHg, awake ABP >135/85 mmHg, and/or sleep ABP >120/70 mmHg are an indication of the presence of hypertension.^[2] ABPM is also useful for the diagnosis of autonomic dysfunctions, obstructive sleep apnea, and for the identification of the circadian time of hypertension treatment that is beneficial for the diagnosis of the risk for cardiovascular diseases.^[3]

ABP readings can be segmented into specific time windows of interest, for example, mean daytime and nighttime values. Normally, BP decreases or dips during sleep; hence, the mean BP (MBP) during sleep is lower than when awake.^[1] In the general population, the BP of ~70% of individuals dips ≥10% at night. In ~30% of the population, the nocturnal BP remains similar to the daytime average or occasionally rises above the daytime average. This phenomenon is called “nondipping.” Nocturnal BP that is present in ~7% of patients with hypertension has been found to be more predictive for mortality associated with total, cardiovascular, and noncardiovascular diseases than daytime hypertension.^[4] There is a strong correlation between the presence of a nondipping ABP pattern with nocturnal hypertension and the risk of cardiovascular morbidity and mortality.

The use of ABPM in clinical practice has been on the rise.^[1] Several studies have published the outcome of the value of ABPM in the past few years.^{[5],[6],[7],[8]} A majority of these studies were conducted in patients with treated^{[6],[9],[10],[11]} or untreated hypertension^{[12],[13],[14],[15]} and other cardiovascular diseases,^{[16],[17],[18]} cerebrovascular diseases like acute stroke,^{[8],[19],[20],[21]} in the general population,^[22],[23] and during pregnancy.^[5],[24] These studies suggest that a single session of ABPM is more useful in the identification of the risk for cardiovascular disease than standard BP measurements.

This study aimed to investigate the prognostic value of BP variables obtained by 24-h ABPM and gender-related differences following percutaneous transluminal coronary angioplasty (PTCA). We also aimed to assess the 1-year clinical outcomes of these patients.

Methods

This prospective, observational, single-center study was conducted in the Department of Cardiology at Nizam's Institute of Medical Sciences, Hyderabad, India. This study includes 58 patients with or without hypertension who underwent PTCA in this institute from June 2017 to January 2018. Baseline data, such as age, gender, and conventional coronary artery disease (CAD) risk factors; including diabetes mellitus (DM), hypertension, and smoking history were obtained from all patients. However, patients with hemodynamic instability requiring intra-aortic balloon pump, inotropic support, mechanical ventilation, insomnia, and arrhythmia that interfere with ABPM devices were excluded from the study. All patients underwent routine blood investigations, including complete blood counts, blood sugar, liver function tests, lipid profile, blood urea, serum creatinine, and serum electrolytes. All patients were also subjected to electrocardiogram and transthoracic echocardiography. For all patients, the diagnosis and indication for percutaneous coronary intervention (PCI) were recorded. All patients were monitored by ABP for 24-h in the hospital. This study was approved by the Institutional Review Board, and informed written consent was obtained from all participants before the recruitment.

Ambulatory blood pressure monitoring

A portable compact digital recorder (Tonoport V, GE Healthcare) and an analyzer with customized analytical software that was programmed to measure BP were used to monitor the 24-h ABP recordings. The inflatable cuff was always positioned on the nondominant upper limb. BP was measured at intervals of 15 min during the day from 07:00 to 23:00. BP was also measured at intervals of 30 min during the night from 23:00 to 07:00. Although patients could perform their routine daily activities, they were instructed to remain inactive during the measurements. If >80% of the raw data were valid, recordings were accepted. The analyzed variables include mean systolic BP (SBP), mean diastolic BP (DBP), mean pulse pressure (PP), mean pulse-wave velocity (PWV), and the presence or absence of dipping.

Statistical analysis

Descriptive statistics were used to summarize continuous and quantitative variables, and the Student's t-test was used for comparison between variables. Chi-square test was used to compare categorical data. The primary endpoint was the incidence of a major adverse cardiac event (MACE). The secondary endpoint was the incidence of combined clinical and laboratory events. Logistic regression was performed to identify the predictors of combined clinical and laboratory events.

Follow-up

Follow-up data were collected using either clinical chart review visits or telephonic interactions using structured questionnaires developed for this study to determine the clinical outcomes at 1-year after the index procedure. Supporting clinical documents were sought when necessary. The rate of MACE defined as the composite of death, myocardial infarction (MI), and target lesion revascularization during the follow-up period after the index procedure was considered as the main clinical outcome measure during the follow-up. In addition, combined clinical and laboratory abnormalities were also seen, which may reflect both short- and long-term effects of changes of ABP in post-PCI patients.

Results

The demographic details of the study participants are listed in [Table 1] and [Figure 1]a. Of the 58 patients, 10 (17.2%) were female and 48 (82.8%) were male. The mean age of the study population was 59.4 ± 9.54 years [Figure 1]a. Overall, 48 (82.8%) patients had DM, 51 (87.9%) patients had hypertension, and 23 (39.7%) patients had a history of smoking [Table 1]. Chronic stable angina (CSA) (62.1%) was the most common presentation in this study. The gender differences in DM and hypertension are illustrated in [Figure 1]b. All female patients had DM and 90% of female patients had hypertension.

Table 1: Demographics of the study population (n=58)

Click here to view

Figure 1: (a) Gender distribution of the study population. (b) Gender distribution of diabetes mellitus and hypertension in the study population. (c) Comparison of the age between male and female patients

Click here to view

A comparison of the gender differences in the baseline characteristics is featured in [Table 2]. The age of the patients, presence of DM and hypertension, number of stents/patient, mean ejection fraction (EF), and number of diseased vessels as detected by coronary angiography were comparable between groups. However, male patients were more likely to have a history of alcohol consumption and smoking. There was no significant difference in the mean age between female and male patients (58.20 vs. 59.71 years) [Figure 1]c.

Table 2: Comparison of clinical risk factors, and coronary angiography data in both female and male patients

Click here to view

Different variables were noted from the ABPM. There were no significant differences between female and male patients in the various parameters that were obtained from ABPM. The MBP of female and male patients was comparable (102.50 ± 11.63 vs. 102.08 ± 13.31). The average PWV among female and male patients was similar (07.02 ± 1.95 vs. 06.30 ± 2.48). There were no statistically significant gender differences in mean SBP, DBP, and PP. A similar mean heart rate (HR) was observed among female and male patients (74.00 ± 11.81 vs. 73.65 ± 17.91) [Table 3].

Table 3: Comparison of ambulatory blood pressure parameters in both female and male patients

Click here to view

Among 58 patients, 25 (43%) patients had nocturnal dipping, and 33 (57%) patients did not have nocturnal dipping. Female patients were more likely to have nondipping upon comparison of the various demographic, clinical, and laboratory parameters between nocturnal dippers and blunted dippers; however, it was not statistically significant. There was a significant difference in the age of nondippers and dippers (56.88 ± 8.01 vs. 62.84 ± 10.47; P < 0.02). Patients with a prior history of DM had a nonsignificant nondipping nocturnal BP compared to patients without DM [Table 4]. Similarly, patients with a prior history of hypertension had a nonsignificant nondipping nocturnal BP compared to normotensive patients [Table 4]. Although the mean DBP and arterial MBP were higher in the nondippers than the dippers, it was not statistically significant. The mean EF and the mean PWV were similar in both nondippers and dippers. However, there was a significant difference between nondippers and dippers in the mean PP (55.85 ± 10.09 vs. 45.04 ± 6.91; P < 0.001). Moreover, the mean HR was more in the dippers than in the nondippers, but was not statistically significant [Table 4]. Mean CAD severity and type of presentation were not significantly different between nondippers and dippers.

Table 4: Comparison of various parameters among dippers and nondippers

Click here to view

At 1-year follow-up, two patients were symptomatic. Of the two patients who were symptomatic, one patient died, whereas the other patient developed CSA. The MACE rate was 1.7% (1/58). The MACE rate was too small to compare between dippers and nondippers. Deterioration of the left ventricular dysfunction (LVD) occurred in three patients. However, combined clinical and laboratory events were comparable between dippers and nondippers, and there was no statistically significant difference between the two groups. Contrast-induced nephropathy (CIN) was seen in three other patients, that is, it was 12% among dippers, which was more as compared to the nondippers (not a single case). However, the difference was not statistically significant [Table 5]. Binary logistic regression showed that only max DBP (P = 0.012) and min DBP (P = 0.019) were predictors of combined clinical and laboratory events.

Table 5: Comparison of follow-up data between dippers and nondippers

Click here to view

Discussion

Arterial BP follows a circadian rhythm. It is higher during the day than at the night.^[25],[26] The diurnal rhythm of arterial BP can be continuously monitored by 24-h ABPM. If the nocturnal fall in BP is <10% of the BP during the day, such individuals are called “nondippers.”^[27] The mechanisms leading to an abnormal diurnal variation in BP are not clear. However, blunted diurnal BP variation has been seen to be a strong predictor of death, in large part, due to its association with other cardiovascular risk factors.^[28] A possibility of a cardiac autonomic dysfunction in prehypertensive, nondipper patients is suspected.^[29] In patients with essential hypertension, a lack of nocturnal decline in BP was found to be a good predictor of cardiovascular prognosis.^[14] Other studies have demonstrated that nondipper pattern can predict target organ damage, including stroke, renal failure, type I diabetes, and adverse cardiovascular events.^{[30],[31],[32]} In one study, patients with CAD often lacked a fall in nocturnal BP, which was shown to increase the risk of future coronary events, including acute coronary syndrome.^[33] Nondipping morning BP was seen to be an independent predictor of hypertensive target organ damage in elderly patients with isolated systolic hypertension.^[34] In patients with severe renal failure and proteinuria, nondipping or reverse dipping pattern, and masked and sustained hypertension were found to be more common.^[35] In patients with dipper and nondipper hypertension, nondipping BP pattern was found to be related to impaired the left ventricular contraction.^[36] In this study, women were more likely to have blunted nocturnal dipping compared with men; however, this was not statistically significant. Previous studies have also reported the same finding.^[37] Hence, women with CAD are exposed to a higher nocturnal BP and, therefore, are at a higher risk for target organ damage and adverse clinical outcomes. This study also reported an association between blunted nocturnal BP dipping in women and CAD and advancing age.^[37] This finding was also made in our study; however, it was not statistically significant. In our study, the presence of other comorbid diseases, including DM and hypertension were more among nondippers than dippers; although this difference was not statistically significant. In addition, ambulatory PP was found to be significantly more elevated in nondippers than in dippers. Similar findings were also reported in other studies.^[14] This important study by Verdecchia P et al. concluded that in untreated essential hypertensive White patients, ambulatory PP was a potent independent predictor of a total cardiovascular risk.^[15] In another study, for increased arterial stiffness or already diseased arteries, ambulatory PP was found to be a more accurate marker than office PP.^[38] A higher PP was seen to be associated with cardiac events in patients with CAD, as a result of increased load due to increased conduit vessel stiffness that increased the amplitude of PP produced by a given flow wave. This resulted in systolic and lower diastolic pressures for any given mean pressure and a subsequent reduction in stroke volume.^[39]

In this study, at 1-year follow-up, only two patients (3.5%) were found to be symptomatic, out of which, one patient died, whereas CSA was seen to develop in the other patient. As the MACE rate was too small, a comparison could not be made between dippers and nondippers. Although a deterioration of LVD was seen in three patients, the combined clinical and laboratory events between dippers and nondippers were comparable. However, in other follow-up studies, a higher risk of cardiovascular mortality was seen in nondippers than dippers.^[40],[41] However, our study being underpowered for such comparison, direct comparison with these studies may not be appropriate.

Moreover, CIN was seen in dippers but not in nondippers in this study. CIN is commonly seen in patients following PTCA.^[42] In addition, a MI before PTCA or prior history of systolic hypertension is also seen to predict CIN.^[43] In this study, maximum and minimum DBP were shown to predict combined clinical and laboratory events. This is in contrast to other studies that reported SBP to be an important predictor of mortality in older adults than in younger adults.^[44]

Limitations

This study was conducted at a single center and was nonrandomized. A major limitation of the study was a small sample size leading to a smaller incidence of MACE. Hence, it was not possible to find any association between the rate of MACE and ABPM variables.

Conclusion

Immediate post-PCI patients demonstrated comparable clinical, laboratory, and BP parameters between females and males. There were more nondippers among female patients who had undergone PCI. Overall, nondippers had a higher nonsignificant mean DBP and MBP than the dippers. However, the mean PP was significantly higher in nondippers. Although the presence of other comorbid diseases, including CAD, DM, and hypertension were higher in nondippers than in dippers, this increase was not statistically significant and did not influence the nocturnal dipping quality of the BP. The clinical outcomes at 1-year were satisfactory with low rate of MACE. Even though dippers showed more combined clinical and laboratory abnormality events than nondipper, which on contrary expected to be opposite, was not statistically significant.

Acknowledgments

The authors acknowledge CBCC Global Research for providing writing and editing support for this manuscript.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1.	Turner JR, Viera AJ, Shimbo D. Ambulatory blood pressure monitoring in clinical practice: A review. Am J Med 2015;128:14-20.
2.	Parati G, Stergiou G, O'Brien E, Asmar R, Beilin L, Bilo G, et al. European Society of Hypertension practice guidelines for ambulatory blood pressure monitoring. J Hypertens 2014;32:1359-66.
3.	Mancia G, Fagard R, Narkiewicz K, Redón J, Zanchetti A, Böhm M, et al. 2013 ESH/ESC Guidelines for the management of arterial hypertension: The task force for the management of arterial hypertension of the European Society of Hypertension (ESH) and of the European Society of Cardiology (ESC). J Hypertens 2013;31:1281-357.
4.	Kinsara AJ. Ambulatory blood pressure monitoring in daily practice. Indian Heart J 2017;69:788-9.
5.	Shahbazian N, Shahbazian H, Mohammadjafari R, Mousavi M. Ambulatory monitoring of blood pressure and pregnancy outcome in pregnant women with white coat hypertension in the third trimester of pregnancy. J Nephropharmacol 2013;2:5-9.
6.	O'Brien E, McInnes GT, Stanton A, Thom S, Caulfield M, Atkins N, et al. Ambulatory blood pressure monitoring and 24-h blood pressure control as predictors of outcome in treated hypertensive patients. J Hum Hypertens 2001;15 Suppl 1:S47-51.
7.	Carr AA, Bottini PB, Prisant LM. Ambulatory blood pressure monitoring for evaluation and management of hypertensives: Effect on outcome and cost effectiveness. J Clin Pharmacol 1992;32:610-3.
8.	Zis P, Vemmos K, Spengos K, Manios E, Zis V, Dimopoulos MA, et al. Ambulatory blood pressure monitoring in acute stroke: Pathophysiology of the time rate of blood pressure variation and association with the 1-year outcome. Blood Press Monit 2013;18:94-100.
9.	Zweiker R, Eber B, Schumacher M, Toplak H, Klein W. “Non-dipping” related to cardiovascular events in essential hypertensive patients. Acta Med Austriaca 1994;21:86-9.
10.	Yamamoto Y, Akiguchi I, Oiwa K, Hayashi M, Kimura J. Adverse effect of nighttime blood pressure on the outcome of lacunar infarct patients. Stroke 1998;29:570-6.
11.	Redon J, Campos C, Narciso ML, Rodicio JL, Pascual JM, Ruilope LM. Prognostic value of ambulatory blood pressure monitoring in refractory hypertension: A prospective study. Hypertension 1998;31:712-8.
12.	Staessen JA, Thijs L, Fagard R, O'Brien ET, Clement D, de Leeuw PW, et al. Predicting cardiovascular risk using conventional vs. ambulatory blood pressure in older patients with systolic hypertension. Systolic hypertension in Europe trial investigators. JAMA 1999;282:539-46.
13.	Verdecchia P, Porcellati C, Schillaci G, Borgioni C, Ciucci A, Battistelli M, et al. Ambulatory blood pressure. An independent predictor of prognosis in essential hypertension. Hypertension 1994;24:793-801.
14.	Verdecchia P, Borgioni C, Ciucci A, Gattobigio R, Schillaci G, Sacchi N, et al. Prognostic significance of blood pressure variability in essential hypertension. Blood Press Monit 1996;1:3-11.
15.	Verdecchia P, Schillaci G, Borgioni C, Ciucci A, Pede S, Porcellati C. Ambulatory pulse pressure: A potent predictor of total cardiovascular risk in hypertension. Hypertension 1998;32:983-8.
16.	Mortensen RN, Gerds TA, Jeppesen JL, Torp-Pedersen C. Office blood pressure or ambulatory blood pressure for the prediction of cardiovascular events. Eur Heart J 2017;38:3296-304.
17.	Shen J, Li ZM, He LZ, Deng RS, Liu JG, Shen YS. Comparison of ambulatory blood pressure and clinic blood pressure in relation to cardiovascular diseases in diabetic patients. Medicine (Baltimore) 2017;96:e7807.
18.	Shimbo D, Abdalla M, Falzon L, Townsend RR, Muntner P. Studies comparing ambulatory blood pressure and home blood pressure on cardiovascular disease and mortality outcomes: A systematic review. J Am Soc Hypertens 2016;10:224-34.e17.
19.	Tsivgoulis G, Pikilidou M, Katsanos AH, Stamatelopoulos K, Michas F, Lykka A, et al. Association of ambulatory blood pressure monitoring parameters with the Framingham stroke risk profile. J Neurol Sci 2017;380:106-11.
20.	Cai A, Liu C, Zhou D, Liu X, Zhong Q, Li X, et al. Ambulatory blood pressure is superior to clinic blood pressure in relation to ischemic stroke in both diabetic and nondiabetic patients. Blood Press Monit 2017;22:314-21.
21.	Kwon HS, Lim YH, Kim HY, Kim HT, Kwon HM, Lim JS, et al. Association of ambulatory blood pressure and heart rate with advanced white matter lesions in ischemic stroke patients. Am J Hypertens 2014;27:177-83.
22.	Lurbe E, Torró MI, Alvarez J. Ambulatory blood pressure monitoring in children and adolescents: Coming of age? Curr Hypertens Rep 2013;15:143-9.
23.	Lindroos AS, Johansson JK, Puukka PJ, Kantola I, Salomaa V, Juhanoja EP, et al. The association between home vs. ambulatory night-time blood pressure and end-organ damage in the general population. J Hypertens 2016;34:1730-7.
24.	Hermida RC, Ayala DE, Iglesias M. Differences in circadian pattern of ambulatory pulse pressure between healthy and complicated pregnancies. Hypertension 2004;44:316-21.
25.	Richardson DW, Honour AJ, Fenton GW, Stott FH, Pickering GW. Variation in arterial pressure throughout the day and night. Clin Sci 1964;26:445-60.
26.	Millar-Craig MW, Bishop CN, Raftery EB. Circadian variation of blood-pressure. Lancet 1978;1:795-7.
27.	Verdecchia P, Schillaci G, Porcellati C. Dippers versus non-dippers. J Hypertens Suppl 1991;9:S42-4.
28.	Brotman DJ, Davidson MB, Boumitri M, Vidt DG. Impaired diurnal blood pressure variation and all-cause mortality. Am J Hypertens 2008;21:92-7.
29.	Erdem A, Uenishi M, Küçükdurmaz Z, Matsumoto K, Kato R, Hara M, et al. Cardiac autonomic function measured by heart rate variability and turbulence in pre-hypertensive subjects. Clin Exp Hypertens 2013;35:102-7.
30.	Ohkubo T, Imai Y, Tsuji I, Nagai K, Watanabe N, Minami N, et al. Relation between nocturnal decline in blood pressure and mortality. The Ohasama study. Am J Hypertens 1997;10:1201-7.
31.	Lurbe E, Redon J, Kesani A, Pascual JM, Tacons J, Alvarez V, et al. Increase in nocturnal blood pressure and progression to microalbuminuria in type 1 diabetes. N Engl J Med 2002;347:797-805.
32.	Davidson MB, Hix JK, Vidt DG, Brotman DJ. Association of impaired diurnal blood pressure variation with a subsequent decline in glomerular filtration rate. Arch Intern Med 2006;166:846-52.
33.	Kang YY, Li Y, Wang JG. Ambulatory blood pressure monitoring in the prediction and prevention of coronary heart disease. Curr Hypertens Rep 2013;15:167-74.
34.	Zain-El MH, Snincak M, Pahuli K, Solarova Z, Hrabcakova P. Non-dipping morning blood pressure and isolated systolic hypertension in elderly. Bratisl Lek Listy 2013;114:150-4.
35.	Cha RH, Kim S, Ae Yoon S, Ryu DR, Eun Oh J, Han SY, et al. Association between blood pressure and target organ damage in patients with chronic kidney disease and hypertension: Results of the APrODiTe study. Hypertens Res 2014;37:172-8.
36.	Karakas MF, Buyukkaya E, Kurt M, Karakas E, Buyukkaya S, Akcay AB, et al. Assessment of left ventricular dyssynchrony in dipper and non-dipper hypertension. Blood Press 2013;22:144-50.
37.	Sherwood A, Bower JK, Routledge FS, Blumenthal JA, McFetridge-Durdle JA, Newby LK, et al. Nighttime blood pressure dipping in postmenopausal women with coronary heart disease. Am J Hypertens 2012;25:1077-82.
38.	Witteman JC, Grobbee DE, Valkenburg HA, van Hemert AM, Stijnen T, Burger H, et al. J-shaped relation between change in diastolic blood pressure and progression of aortic atherosclerosis. Lancet 1994;343:504-7.
39.	Mitchell GF, Moyé LA, Braunwald E, Rouleau JL, Bernstein V, Geltman EM, et al. Sphygmomanometrically determined pulse pressure is a powerful independent predictor of recurrent events after myocardial infarction in patients with impaired left ventricular function. SAVE investigators. Survival and ventricular enlargement. Circulation 1997;96:4254-60.
40.	Ohkubo T, Hozawa A, Yamaguchi J, Kikuya M, Ohmori K, Michimata M, et al. Prognostic significance of the nocturnal decline in blood pressure in individuals with and without high 24-h blood pressure: The Ohasama study. J Hypertens 2002;20:2183-9.
41.	Hermida RC, Ayala DE, Mojón A, Fernández JR. Blunted sleep-time relative blood pressure decline increases cardiovascular risk independent of blood pressure level-the “normotensive non-dipper” paradox. Chronobiol Int 2013;30:87-98.
42.	Rear R, Bell RM, Hausenloy DJ. Contrast-induced nephropathy following angiography and cardiac interventions. Heart 2016;102:638-48.
43.	Nough H, Eghbal F, Soltani M, Nejafi F, Falahzadeh H, Fazel H, et al. Incidence and main determinants of contrast-induced nephropathy following coronary angiography or subsequent balloon angioplasty. Cardiorenal Med 2013;3:128-35.
44.	Taylor BC, Wilt TJ, Welch HG. Impact of diastolic and systolic blood pressure on mortality: Implications for the definition of “normal”. J Gen Intern Med 2011;26:685-90.