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Original Article

Acta Cardiol Sin 2004;20:7-14

Congestive Heart Failure

C-Reactive Protein Levels in Chronic Congestive Heart Failure

Wen-Pin Huang, Wei-Hsian Yin, Hsu-Lung Jen, Meng-Cheng Chiang, An-Ning Feng and Mason Shing Young1

Background: Serum concentrations of C-reactive protein (CRP) are elevated in patients with congestive heart failure (CHF). However, clinical data about the prognostic value of CRP levels in patients with chronic stable CHF are sparse. We hypothesized that measurement of CRP might provide prognostic information in these patients. Methods: We measured serum levels of CRP in 72 patients with chronic CHF and left ventricular ejection fraction (LVEF) < 50%. Major adverse cardiac events (death or hospitalization with worsening CHF) during a median follow-up period of 449 days were determined. Multivariate Cox regression analysis was performed to identify independent predictors of major adverse cardiac events. Results: The concentrations of CRP in the sample population were significantly increased with the severity of CHF. The 25 patients who had adverse events had significantly higher CRP levels (p = 0.0065) than the 47 patients who were event-free. We further divided the 72 CHF patients into tertiles on the basis of this sample, with the cutoff points for each tertile being ? 2.69, > 2.69 to ? 5.38, and > 5.38 mg per liter, respectively. The differences between event-free curves were insignificant between tertiles 1 and 2 but were significant between tertiles 1 and 3 and between tertiles 2 and 3 (p = 0.0048, p = 0.0103, respectively). In a multivariate analysis (n = 58), left ventricular end-diastolic pressure (LVEDP) and serum levels of CRP > 5.38 mg per liter were found to be independently significant predictors for major adverse cardiac events in patients with chronic CHF. The CRP levels were significantly correlated with LVEDP (r = 0.26, p = 0.048; n = 58). Conclusions: These findings suggest that the levels of CRP are related to clinical outcomes and that measurement of CRP has the potential to play an important role as an adjunct for risk assessment in patients with chronic CHF.

Key Words: C-reactive protein ? Congestive heart failure ? Prognosis

INTRODUCTION

Activation of the immune system has been implicated in the pathogenesis of congestive heart failure (CHF).1,2 Cytokines such as tumor necrosis factor alpha (TNF-a) and interleukin-6 are significantly elevated, producing negative inotropic effects on the heart, and the levels of

Received: April 29, 2003

Accepted: October 7, 2003

Division of Cardiology, 1Department of Internal Medicine,

Cheng-Hsin General Hospital, Taipei, Taiwan.

Address correspondence and reprint requests to: Dr. Mason Shing

Young, Department of Internal Medicine, Cheng-Hsin General Hospital,

No. 45, Cheng-Hsin Street, Taipei 112, Taiwan. Tel: 886-2-2826-

1242; Fax: 886-2-2826-1242; E-mail: yin.wh@msa.

these cytokines may be negatively associated with prognosis.2,3

C-reactive protein (CRP), as a marker of inflammation, has been shown to be associated with an increased risk of various cardiovascular diseases.4-7 The serum concentration of CRP is also elevated in patients with congestive heart failure (CHF),8-10 and Gottdiener et al. reported that increased CRP was an independent predictor of incident CHF in a community-based elderly population.11 However, clinical data about the prognostic value of CRP in patients with chronic CHF are sparse and inconsistent.9,10 The likely reason for this is that the mildly elevated CRP concentrations in these patients fall well within the range found in healthy subjects, and the standard clinical assays for CRP lack sensitivity within the

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Wen-Pin Huang et al.

low-normal range: thus they cannot be used effectively for cardiovascular risk prediction. Since high-sensitivity commercial assays for CRP are now available,12 we hypothesized that measurement of CRP might provide prognostic information in these patients.

This study was designed to evaluate the level of CRP using high-sensitivity kits in patients with chronic CHF and to examine the relation between the degree of CRP elevation and clinical outcome.

METHODS

Patient population Seventy-two patients (48 men and 24 women, aged

46 to 76 years [mean 61 ? 15] with chronic CHF were enrolled. Patients were included if, at the time of enrollment, they had New York Heart Association (NYHA) class II to IV symptoms of heart failure and a left ventricular ejection fraction (LVEF) of < 50% by left ventriculography with radionuclide or contrast medium. Although all patients had low LVEFs, they had all been clinically stable without signs or symptoms of pulmonary congestion for at least two weeks before their entry into this study. Patients were excluded if there was severe comorbidity, renal failure, myocardial infarction or unstable angina in the 6 weeks leading up to enrollment, leukocytosis (WBC count > 10000 per deciliter), infection or an inflammatory illness such as sepsis, malignancy, arthritis or connective tissue disease.

An age-matched group of 16 volunteers provided blood samples for use as a control. All of these subjects were free of heart disease and other major medical problems.

Baseline clinical evaluation and hemodynamic measurements

Baseline clinical evaluation was performed on the 72 patients with CHF. Sixty-nine patients underwent cardiac catheterization or coronary arteriography for clinically indicated purposes. Informed consent was obtained from all patients according to a protocol approved by the committee on human investigation at our institution. Left-sided cardiac catheterization, including left ventriculography and coronary arteriography, was performed in 58 patients. Right-sided cardiac catheterization, both with and without endomyocardial biopsy, was performed in 13 and in 41 patients, respectively. Right heart pressure, such as pul-

monary capillary wedge pressure, was measured with a 7Fr Swan-Ganz catheter, and cardiac output was measured by the thermodilution technique.

The LVEF was determined by left ventriculography with standard radionuclide or contrast medium.

Blood sampling and measurement of circulating levels of CRP

For those 54 patients who underwent right heart catheterization for clinical (noninvestigational) evaluation, venous blood was drawn during right heart catheterization (central vein). For other patients, blood samples were collected into vacuum tubes at bedside (peripheral vein). All samples were then frozen to ?20 ?C and were stored at that temperature until analysis. The time interval between blood sampling and LVEF studies for every patient was less than one week.

Samples were assayed for CRP with a validated, high-sensitivity assay (DRG Instruments, Germany). The intra-assay and inter-assay coefficients for each factor were about 5% and about 10%, respectively.

Clinical follow-up All patients were followed either in-hospital or

through regular outpatient visits. Clinical information regarding major adverse cardiac events (cardiac death or hospitalization with a primary diagnosis of worsening CHF) during a median follow-up period of 449 days was provided by the treating cardiologist without knowledge of the CRP levels.

Data analysis All values, except for the CRP level, were expressed

as mean ? SD. Because the distribution of the CRP levels in these patients did not follow a normal distribution, they were expressed by a median (25th to 75th percentiles).

The patients with CHF were divided into two groups: mild CHF (NYHA class II) and severe CHF (NYHA class III or IV) groups. Comparisons of the levels of CRP among these 2 groups and the controls were determined by means of a Kruskal-Wallis one-way analysis of variance on ranks test.

The CHF patients were then divided into those who had major adverse cardiac events during follow-up and those who were event-free. Univariate comparisons of clinical and hemodynamic characteristics between these two groups were made with the Student's t test for quanti-

Acta Cardiol Sin 2004;20:7-14

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CRP in Chronic Heart Failure

tative data and with the Fisher exact test for qualitative data. Levels of CRP were compared between these two groups by the Wilcoxon rank-sum test. Cox proportional hazards analysis was performed to determine the significance of LVEF, left ventricular end-diastolic pressure (LVEDP) and circulating levels of CRP as independent predictors of CHF.

We also divided the population data into three groups of equal numbers of patients (24 in each) with respect to increasing CRP levels, and constructed Kaplan-Meier curves for event-free survival analysis. The differences between event-free curves were tested by a log rank test.

Linear regression analysis was used to determine the correlation between the levels of CRP, LVEF, LVEDP and various hemodynamic parameters derived from cardiac catheterization.

A p value < 0.05 was considered statistically significant.

RESULTS

Patient characteristics and hemodynamic data A sample of 72 patients meeting the study criteria was

chosen; their baseline characteristics are shown in Table 1. There were more men than women in this sample. The

cause of heart failure was ischemic heart disease in 21 (29%) patients, dilated cardiomyopathy in 21, and valvular heart disease in 30. The mean LVEF was 36%; 32 patients were in NYHA class II (mild CHF group), 40 were in class III or IV (severe CHF group). All patients were clinically stable on blood sampling while receiving continuous therapy for heart failure. Thirty-nine patients used digoxin and fifty-four used diuretics; 45 patients were also treated with angiotensin-converting enzyme inhibitors, 30 with beta-blockers, and 31 with vasodilators

Table 1. Baseline clinical characteristics of 72 patients with congestive heart failure

Age (y) LVEF (%)

61 ? 15 36 ? 14

Men Ischemic heart failure NYHA class II

48 (67%) 21 (29%) 32 (44%)

NYHA class III NYHA class IV Diuretics

24 (33%) 16 (22%) 54 (75%)

ACEI/ARB ?eta-blocker Digoxin

45 (63%) 30 (42%) 39 (54%)

Vasodilator

31 (43%)

LVEF = left ventricular ejection fraction; NYHA= New York Heart Association; ACEI/ARB = angiotensin-converting enzyme inhibitors or angiotensin receptor blockers.

Table 2. Patient characteristics and hemodynamic data in patients with congestive heart failure who had major adverse cardiac events during follow-up and those who were event-free

MACE(-) (n = 47)

MACE(+) (n = 25)

p value

Age (yrs) Male, n (%) LVEF (%) Ischemic heart failure Diuretics Digitalis ACEI/ARB therapy Vasodilator therapy Beta-blockers Cardiac index (L/min/M2) Left ventricular end-diastolic pressure (mmHg) Systemic vascular resistance (dynes-sec-cm-5) Pulmonary vascular resistance (dynes-sec-cm-5) Total pulmonary resistance (dynes-sec-cm-5)

C-reactive protein (mg/L)

60 ? 15 30 (64%) 41 ? 11

10 34 23 28 17 19 2.0 ? 0.6 (n = 28) 21 ? 8 (n = 39) 2600 ? 939 (n = 29) 294 ? 192 (n = 24) 846 ? 468 (n = 24)

3.12 (2.24 - 4.95)

63 ? 14 18 (72%) 27 ? 13

11 20 16 17 14 11 2.1 ? 0.7 (n = 16) 28 ? 10 (n = 19) 2301 ? 888 (n = 16) 273 ? 195 (n = 16) 1039 ? 615 (n = 16)

5.76 (2.89 - 25.22)

NS NS < 0.0001 NS NS NS NS NS NS NS 0.007 NS NS NS 0.0065

MACE = major adverse cardiac event; LVEF = left ventricular ejection fraction; ACEI/ARB = angiotensin-converting enzyme inhibitors or angiotensin receptor blockers.

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on blood sampling. The CHF patients were then divided into those who

had major adverse cardiac events during follow-up and those who were event-free (Table 2). No significant differences in age, sex or cause of CHF were detected between the two groups. However, by univariate analysis, the mean LVEF was significantly lower (p < 0.0001) and the LVEDP was significantly higher (p = 0.007) in the group with major adverse cardiac events than in the event-free group.

pared in Figure 2. The 25 patients who had adverse events had significantly higher CRP levels (p = 0.0065) than the

Circulating levels of CRP in patients with CHF Not all of the 72 patients with CHF had elevated CRP.

However, the concentrations of CRP were significantly higher in the CHF patients than in the 16 healthy controls and increased with the severity of CHF, especially in the severe (NYHA class III or IV) group (Figure 1).

Prognosis The median follow-up period was 449 days (246 to

497 days, 25th to 75th percentiles). There was a 35% (25 of 72) overall event rate in the CHF population. Seven of the seventy-two patients died of cardiac causes (4 died of sudden death without premonition of the progression of symptoms, presumed to be due to arrhythmia, and 3 of intractable end-stage CHF) during the follow-up period. Eighteen patients were readmitted for worsening heart failure.

The exact CRP levels of the patients of both adverse-event and event-free groups are shown and com-

Figure 2. The circulating levels of C-reactive protein (CRP) in patients with congestive heart failure who had no major adverse cardiac events [MACE (-)] versus those who did have adverse events [MACE (+)] during follow-up.

Figure 1. Circulating levels of C-reactive protein (CRP) in patients with chronic congestive heart failure (CHF). Control = age-matched control

subjects (n = 16); Mild CHF = New York Heart Association (NYHA) class II (n = 32); Severe CHF = NYHA class III or IV (n = 40). Values are expressed by a median (25th to 75th percentiles). * p < 0.0001.

Acta Cardiol Sin 2004;20:7-14

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CRP in Chronic Heart Failure

47 patients who were event-free. This is further illustrated by a Kaplan-Meier analysis

of event-free survival, dividing the 72 CHF patients into 3 equal groups (tertiles) of 24 each based on their levels of CRP (shown in Figure 3). On the basis of this sample, the cutoff points for each tertile were ? 2.69, >2.69 to ? 5.38, and > 5.38 mg per liter, respectively. The differences between event-free curves were insignificant between tertiles 1 and 2 but were significant between tertiles 1 and 3 and between tertiles 2 and 3 (p = 0.0048, p = 0.0103, respectively).

Correlation between concentrations of CRP, LVEDP and LVEF

According to the Cox proportional hazards analysis (n = 58), CRP > 5.38 mg per liter and LVEDP were found to be independently significant predictors for major adverse cardiac events in these CHF patients (Table 3). The circulating levels of CRP were significantly correlated with LVEDP (r = 0.26, p = 0.048; n = 58), however, the CRP

Table 3. Predictors of events during follow-up: multivariate Cox proportional hazard analysis (n = 58)

Variable

95% C.I. for Coefficient Hazard ratio hazard ratio p value

LVEF LVEDP CRP > 5.38

0.942 1.222 1.07

2.564 3.394 2.915

0.759 - 8.66 1.076 - 10.707 1.099 - 7.732

0.129 0.037 0.032

LVEF = left ventricular ejection fraction; LVEDP = left ventricular end-diastolic pressure; CRP = C-reactive protein (mg/L).

levels were minimally correlated with LVEF (r = -0.22, p = 0.063) (Figure 4).

DISCUSSION

Comparison with previous studies Chronic CHF is the final common pathway of a variety

of cardiac disorders, and it is usually progressive. Recent studies suggest that CHF may, in part, be an inflammatory disease, and it is well known that proinflammatory cytokines such as TNF-a and interleukin-6 are significantly elevated in such patients and that their levels are negatively associated with clinical outcomes.1-3 C-reactive protein, an inflammatory marker synthesized in the liver, has been shown to predict myocardial infarction, stroke and vascular death in a variety of settings, and it has been proven to be one of the strongest independent predictors of future cardiovascular events in apparently healthy men and women.4-7 Increased CRP has also been reported to be an independent predictor of incident CHF in a community-based elderly population.11

Although the serum concentration of CRP is elevated in patients with CHF,8-10 clinical data about the prognostic value of CRP in patients with chronic CHF are lacking and inconsistent.9,10 This is because the mildly elevated CRP concentrations in these patients fall well within the range found in healthy subjects. Traditionally, clinical assays for CRP typically have a lower detection limit of 3 to 8 mg/L, and it has been suggested that CRP values of less

Figure 3. Kaplan-Meier event probability for patients with chronic congestive heart failure, stratified into increasing tertiles on the basis of circulating levels of C-reactive protein (CRP).

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Acta Cardiol Sin 2004;20:7-14

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