Patients With Hypertensive Crises Who Are Admitted to a Coronary Care Unit: Clinical Characteristics and Outcomes

Authors


Address for correspondence: Héctor González Pacheco, MD, Juan Badiano number 1 Colonia Sección XVI, C.P 14080, Tlalpan, Mexico City, Mexico

E-mail: hectorglezp@hotmail.com

Abstract

Patients with hypertensive crises, especially hypertensive emergencies, require immediate admittance to an intensive care unit for rapid blood pressure (BP) control. The authors analyzed the prevalence of hypertensive crisis, the clinical characteristics, and the evolution of patients with hypertensive emergencies and urgencies. Patients were divided into 3 groups according to their BP values: group I, predominant systolic hypertension (≥180/≤119 mm Hg); group II, severe systolic and diastolic hypertension (≥180/≥120 mm Hg); and group III, predominant diastolic hypertension (≤179/≥120 mm Hg). Of all of the patients admitted to a coronary care unit, 538 experienced a hypertensive crisis, which represented 5.08% of all admissions. Hypertensive emergency was predominant in 76.6% of the cases, which corresponded to acute coronary syndrome and acute decompensated heart failure in 59.5% and 25.2% of the cases, respectively. A pattern of predominant systolic hypertension (≥180/≤119 mm Hg) was most commonly observed in the hypertensive crisis group (71.4%) and the hypertensive emergency group (72.1%). The medications that were most commonly used at onset included intravenous vasodilators (nitroglycerin in 63.4% and sodium nitroprusside in 16.4% of the patients). The overall mortality rate was 3.7%. The mortality rate was 4.6% for hypertensive emergency cases and 0.8% for hypertensive urgencies cases.

Arterial hypertension (HTN) is one of the most common medical problems. It affects approximately 1 billion individuals worldwide. In the United States, approximately 30% of the population older than 18  has some type of hypertension.[1] Hypertension is defined as a systolic blood pressure (SBP) >140 mm Hg or a diastolic blood pressure (DBP) >90 mm Hg.[2] Severe HTN, which is potentially fatal, is referred to as a hypertensive crisis. It is estimated that approximately 1% of patients with hypertension develops a hypertensive crisis at some point.[3] A hypertensive crisis is classified as hypertensive emergency (HTN-E) or hypertensive urgency (HTN-U). HTN-E is characterized by a severe elevation of blood pressure (BP; ≥180/120 mm Hg) with evidence of progressive organ damage or target organ failure. HTN-U is defined as uncontrolled BP without failure or damage to the target organ.[2] Immediate diagnosis and appropriate treatment are crucial to prevent permanent damage.

The objective of our study was to describe the prevalence, clinical features, and evolution of patients admitted with a diagnosis of hypertensive crisis into a coronary care unit within a tertiary care center in cardiovascular disease.

Methods and Materials

Information was obtained from the database at the coronary care unit (CCU) of the National Institute of Cardiology in Mexico City. Demographic and clinical data were obtained from patients admitted with a diagnosis of hypertensive crisis from October 2005 to December 2011. The criteria that were used to determine hypertensive crisis were from the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7),[2] which includes values of SBP ≥180 mm Hg and/or DBP ≥120 mm Hg at the time of admission. Hypertensive urgencies are those situations associated with severe elevations in BP without progressive target organ dysfunction, and hypertensive emergency was diagnosed when damage to any target organ was evident. This included acute coronary syndrome (ACS), acute decompensated heart failure (ADHF), acute aortic syndrome, ischemic or hemorrhagic stroke, and acute kidney injury (Table 1). The patients were divided into 2 groups: HTN-E and HTN-U. To analyze the pattern of arterial pressure values, patients were subdivided into 3 groups according to their BP as follows: group I, predominant systolic hypertension (sHTN) (SBP ≥180/DBP ≤119 mm Hg); group II, severe systolic and diastolic hypertension (cHTN) (SBP ≥180/DBP ≥120 mm Hg); and group III, predominant diastolic hypertension (dHTN) (SBP ≤179/DBP ≥120 mm Hg).

Table 1. Damage to a Target Organ in Hypertensive Emergency
  1. Abbreviations: AAS, acute aortic syndrome; ACS, acute coronary syndrome; ADHF, acute decompensated heart failure; AKI, acute kidney injury.

ACSPresence of precordial pain, electrocardiographic changes, and enzymatic elevation indicative of myocardial damage
ADHFPresence of dyspnea, crackles on thoracic auscultation, and radiographic evidence thoracic suggestive of pulmonary venocapillary hypertension
AASPresence of anterior or posterior thoracic pain, widened mediastinum on chest radiography, and findings on echocardiography, computed tomography, or magnetic resonance imaging findings suggestive of aortic dissection
Ischemic or hemorrhagic strokePresence of altered mental state and evidence of ischemic or hemorrhagic events on tomography and magnetic resonance[4]
Acute kidney injuryThe Kidney Disease Improving Global Outcomes Clinical Practice Guidelines for AKI (KDIGO)[5]

Statistical Analysis

Nominal variables are presented in frequencies and percentages; comparisons were performed using a chi-square (χ2) or Fisher exact test, depending on the frequency of the expected events. Quantitative variables are expressed as mean±standard deviation (SD) and were compared using Student t test. The results are reported as two-tailed significance, odds ratio, and 95% confidence intervals. Statistical significance was considered at P≤.05. SPSS software version 13 (SPSS, Chicago, IL) was used for statistical analysis.

Results

During the analyzed period, 9255 patients were admitted consecutively to the CCU; 538 patients (5.08%) met the hypertensive crisis criteria, and the majority of patients (76.6%) were considered to have HTN-E. The baseline characteristics of the patients are shown in Table 2. The average age of the total group was 63.2±13.1 years; patients with HTN-U were older (65.2±14.3 vs 62.6±12.7 years, P=.04). In this study, 54.5% of cases were men, and there more men in the HTN-E group (43.7% vs 57.8% P=.004). Among variables that were more prevalent in the HTN-E population than in HTN-U population, there were current smoking status (19.2% vs 11.1%, P=.02), previous myocardial infarction (23.3% vs 6.3%, P=.0001), dyslipidemia (40.3% vs 28.6%, P=.01), and heart failure (17% vs 0.8%, P=.0001). Variables such as previous history of hypertension, renal failure, diabetes mellitus, atrial fibrillation, and stroke were not statistically significant between the two groups.

Table 2. Baseline and Clinical Characteristics of Patients With Hypertensive Crisis
 Hypertensive Crisis (n=538)Urgencies (n=126)Emergencies (n=412)P Value
  1. Abbreviations: DBP, diastolic blood pressure; MI, myocardial infarction; SBP, systolic blood pressure.

Age, y63.2±13.1365.2±14.362.6±12.7.04
Men, %54.543.757.8.004
Medical history
Current smoker, %17.311.119.2.02
Hypertension, %86.684.987.1.30
Diabetes, %40.736.542.16
Dyslipidemia, %37.528.640.3.01
Heart failure, %13.20.817.0001
Renal dysfunction, %13.211.913.6.37
Previous MI, %19.36.323.3.0001
Stroke, %4.15.63.6.23
Presentation
SBP, mm Hg195.1±18.7201.2±20.2193.3±17.9.0001
DBP, mm Hg107.2±19.9106.7±22.8107±18.9.77

SBP was higher in the HTN-U group than in the HTN-E group at the time of initial evaluation (201.2±20.2 mm Hg vs 193.3±17.9 mm Hg, P=.001). There were no differences in DBP between both groups (106.7±22.8 mm Hg vs 107.3±18.9 mm Hg).

Regarding the relationship between BP and the development of hypertensive crisis and hypertensive emergencies, the majority of patients with hypertensive crises (71.4%, 384 of 538) and most of the patients with hypertensive emergencies (72.1%, 297 of 412) were in group 1 (sHTN) (Table 3).

Table 3. Hypertensive Crisis Groups Classified According to Blood Pressure
 Group I ≥180/≤120 mm Hg (n=384)Group II ≥180/≥120 mm Hg (n=132)Group III ≤180/≥120 mm Hg (n=22)
  1. Abbreviations: DBP, diastolic blood pressure; MBP, mean blood pressure; SBP, systolic blood pressure.

Urgencies, %22.728.84.5
Emergencies, %77.371.295.5
SBP, mm Hg191.5±12.5210±23.1165.5±9.6
DBP, mm Hg98.3±13.9130.3±15.5123.2±6.5
MBP, mm Hg129.3±10.9157.1±15.2137.3±5.4

Among the 412 patients with HTN-E, damage to target organs was distributed as follows: 245 patients (59.5%) presented with ACS (104 infarcts with ST-segment elevation, 79 infarcts without ST-segment elevation, and 62 with unstable angina); 104 patients (25.2%) presented with ADHF (22 patients presented with acute pulmonary edema); 26 patients (6.3%) presented with acute aortic syndrome; 21 patients (5.1%) had neurological damage, and 16 patients (3.9%) had acute kidney injury (Figure 1).

Figure 1.

Type of acute target organ damage. ACS indicates acute coronary syndrome; AAS, acute aortic syndrome.

Among all of the patients, 76.2% received an initial treatment with intravenous vasodilators. This treatment was used in 61.9% of cases in the HTN-U group and in 80.6% in the HTN-E group. Nitroglycerin was used in 63.4% of the cases, and nitroprusside was used in 16.4%. Both vasodilators were used together in 19 patients (3.5%). Table 4 shows the frequencies that other antihypertensive treatments (such as angiotensin-converting enzyme inhibitors, β-blockers, hydralazine, and diuretics) were used in the initial stages of treatment.

Table 4. Pharmacologic Agents Used on Admission in the Treatment of Hypertensive Crisis
 Hypertensive Crisis (n=538)Urgencies (n=126)Emergencies (n=412)P Value
  1. Abbreviations: ACE, angiotensin-converting enzyme; IV, intravenous; PO, by mouth.

Vasodilator IV, %76.261.980.6.0001
Nitroprusside, %16.422.214.6.03
Nitroglycerin, %63.441.370.1.0001
ACE inhibitors PO, %78.180.277.4.30
β-Blockers PO, %29.930.229.9.51
Hydralazine PO, %3.54.83.2.27
Diuretics IV, %34.920.639.3.0001

The overall mortality rate for patients with hypertensive crisis in the CCU was 3.7%. Among the 412 patients with HTN-E, there were 19 deaths (4.6%). In the HTN-U group, 1 patient died of a pulmonary infection (0.8%).

Discussion

To date, the treatment of arterial hypertension has drastically reduced the number of severe HTN cases and the development of hypertensive crisis. A hypertensive crisis is frequently described as a rise in SBP ≥180 mm Hg and/or a DBP ≥120 mm Hg. There is little information on the prevalence of hypertensive crisis patients admitted to intensive care units. The present study describes the clinical features and evolution of adult patients admitted to the CCU with a diagnosis of hypertensive crisis. It has been estimated that close to 1% of patients with HTN may develop hypertensive crisis.[3] The prevalence of hypertensive crisis in emergency care units has been calculated to be approximately 3%.[6] In a Brazilian retrospective study that evaluated 76,723 patients admitted to an emergency department, 273 of the patients (0.35%) were considered to have HTN-U and 179 patients (0.23%) were considered to have HTN-E.[7] Similarly, a study from an emergency department in Spain reported a prevalence of hypertensive crisis of approximately 0.65% from a total of 17,952 admitted patients.[8] In our study of 9255 patients admitted to the CCU, 5.08% were admitted for hypertensive crisis, and diagnoses of HTN-E were more common than HTN-U (76.6% vs 23.4% of cases), similar proportions to those reported in the Studying the Treatment of Acute hyperTension (STAT) registry; 1588 patients with acute severe hypertension requiring hospitalization; 59% of patients had acute or end-organ worsened damage; and 20% had no evidence of target organ damage.[9] This finding is in contrast to those observed by Zampaglione, who reported that HTN-Us were more frequent than HTN-Es (76% vs 24%).[6] Hypertensive emergencies account for 25% to 30% of all hypertensive crises.[9] This difference may be explained by the fact that our study focused on a specific high-risk population that required admittance to an intensive care unit in a tertiary care center in cardiovascular disease rather than an emergency department.

Worldwide estimates suggest that no sex differences exist in the prevalence of HTN,[2] however, and men tend to develop more hypertension-related complications as evidenced by the high frequency of HTN-E.[8, 10] In our series of 538 patients with hypertensive crisis, the majority were men (54.5%). A history of HTN was present in 85% of cases. In the HTN-E group, there was a male predominance (57.8%) as well as a history of risk factors such as myocardial infarction and heart failure.

Patients with hypertensive crisis are often chronic hypertensives who are either noncompliant or inadequately treated.[11] However, as many as 28% of patients with hypertensive crisis may not have had a previous history of HTN.[6] A prior history of HTN was present in more than 85% of our cases.

Hypertensive emergency has been considered as severe HTN that causes injury to target organs; however, the elevation in BP is not an absolute diagnostic criterion even though DBP ≥120 mm Hg is more frequently encountered in HTN-E.[12, 13] We found that the group of patients with HTN-U had higher levels of SBP. This means that not only the degree of BP elevation is related to the development of complications, but it must also be considered that the patients' characteristics (eg, the presence of target organ damage previous) make them more susceptible to the harmful effect of severe hypertension. In the group of patients with HTN-U in our study, only 25% had previous target organ damage, so that most of these patients could prevent unnecessary admission. We identified 3 groups of patients with hypertensive crises according to their BP values: group I with predominant sHTN (SBP ≥180/DBP ≤119 mm Hg), group II with elevation of both systolic and diastolic cHTN (SBP ≥180/DBP ≥120 mm Hg), and group III with predominant dHTN (SBP ≤179/DBP ≥120 mm Hg). Most patients with hypertensive crisis and HTN-E were classified in group I, where sHTN was predominant.

Despite the development of effective antihypertensive treatments, the frequency of hospitalizations for an HTN-E increased from 101 per 100,000 US adults in 2000 to 111 per 100,000 in 2007, an average increase of approximately 10%.[14]

Martin and colleagues[15] reported that in 231 patients with HTN-E, the organs affected were related to cardiac events in 59.1% of cases and to neurological events in 40.5% of cases. In our study, cardiovascular injury, including acute aortic syndromes, was present in 91% of cases with HTN-E, with the majority having ACS and ADHF. Neurological damage was present in only 5.1% of the cases, which is in contrast to findings in other studies[6, 15] and could be related to the characteristics of the patients who are admitted to our hospital.

The development of successful antihypertensive therapy has greatly improved the prognosis of patients with HTN-E.[16] The goal of the treatment is a rapid but gradual reduction of BP. Early evaluation of patients is very important to establish the best therapeutic strategy to limit the associated morbidity and mortality.[17] Hypertensive urgency may be treated with oral medications to gradually reduce BP over a period of 24 to 48 hours.[18] Patients with HTN-E must be admitted to an intensive care unit for continuous BP monitoring and parenteral administration of appropriate antihypertensive agents. The initial aim of therapy in HTN-E is not to achieve a normal BP but to reduce BP by no more than 25% within the first hour and, once stabilized, to continue reduction to 160/110 mm Hg or 160/100 mm Hg over the following 2 to 6 hours.[2] An alternative is to reduce DBP by 10% to 15% or to approximately 110 mm Hg in 30 to 60 minutes, if the patient is clinically stable, further gradual reductions toward a normal BP can be implemented over the next 24 to 48 hours.[19] The STAT registry showed a malpractice in BP control in hospitalized patients, the median time to achieve SBP <160 mm Hg (<140 mm Hg for subarachnoid hemorrhage) was 4.0 hours. An aggressive decrease in BP may aggravate hypoperfusion and worsen damage to target organs.[11] ADHF patients have been associated with an increased frequency of adverse events when their BP decreases <120 mm Hg within the first 6 hours.[20] In our series, an initial aggressive treatment based on vasodilators was used in 76.2% of patients. Nitroglycerin was used more often than nitroprusside. The frequent use of intravenous vasodilators in up to 61.9% of cases with HTN-U is striking. Weder and Erickson[21] highlighted the inappropriate use of intravenous antihypertensive agents in up to 60% of hospitalized patients with HTN-U; this practice is potentially very dangerous and these agents should only be administered to patients with an HTN-E. Unfortunately, the term “urgency” has led to an overuse of aggressive treatment in patients with severe uncomplicated HTN. The fact that intravenous vasodilators were used as commonly as noted in both HTN-E and HTN-U was often dictated by the acute comorbidity (eg, ACS) rather than the HTN status itself. Because of its favorable effects on myocardial oxygenation, intravenous nitroglycerin is the best option for hypertensive crisis that is complicated by myocardial ischemia or infarction.[22] Nitroglycerin can also be used as an alternative to nitroprusside to reduce afterload in the treatment of ADHF.[23] Due to the development of effective medications, mortality after an HTN-E diminished from 80% in 1928 to only 10% in 1989.[24] Mortality decreased further to 2.6% after the release of JNC 7 guidelines.[14] Our data show that HTN-E was associated with the worst mortality outcomes. Because of the retrospective nature of this study and confounding acute comorbidities, this observation cannot be considered definitive.

Limitations

We reported the prevalence and clinical features of hypertensive crisis in patients admitted to the CCU of a tertiary center specializing in cardiovascular diseases, which is different from findings reported in emergency departments or other types of intensive care units. Our study had the inherent limitations of a retrospective analysis, including the lack of data regarding previous antihypertensive treatments and adherence to treatment in 86.6% of the patients with prior history of HTN. Poor outpatient control of BP was an independent predictor of subsequent hypertensive crisis in a case-controlled study.[25] We described the antihypertensive medications that were initially used; however, there were no data on the actual response of BP or the time it took to control BP.

Conclusions

The prevalence of hypertensive crisis in the patients admitted to the CCU is approximately 5%. Hypertensive emergency was present in 76% of the cases. Our data confirm a significant risk profile associated with HTN-E that should stimulate continued aggressive management, especially for patients with previous organ damage. Cardiac injury, manifested by ACS and heart failure, was most commonly encountered as secondary organ damage. The pattern of sHTN (>180/<119 mm Hg) was present in most cases. It is essential to evaluate whether it is necessary to continue classifying HTN-U under the hypertensive crisis, since this causes confusion mainly in the treatment of patients who are hospitalized. On the other hand, as well as the BP levels, we believe that the presence of high-risk factors such as previous damage to a target organ would decrease to a quarter of the number of patients hospitalized with HTN-U in our study.

Conflict of Interest Statement

The authors report no specific funding in relation to this research and no conflicts of interest to disclose.

Acknowledgments

The authors thank the secretarial staff of the Coronary Care Unit, Ms Leticia Casiano and Ms Benita Medrano, for their cooperation in the preparation of this manuscript.

Ancillary