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Persistent elevation of C-reactive protein and ischemic heart disease in patients with continuous ambulatory
Soon Bae Kim1, Won Ki Min, Sang Koo Lee
1Department of Internal Medicine, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, Korea.
Insights
Persistent high C-reactive protein (CRP) levels strongly indicate ischemic heart disease (IHD) in continuous ambulatory peritoneal dialysis (CAPD) patients. Early workup for IHD is recommended for CAPD patients with unexplained persistent CRP elevation.
Area of Science:
- Cardiology
- Nephrology
- Clinical Chemistry
Background:
- Inflammation, indicated by elevated C-reactive protein (CRP), is a known risk factor for cardiovascular disease.
- Patients undergoing continuous ambulatory peritoneal dialysis (CAPD) are at increased risk for cardiovascular complications, including ischemic heart disease (IHD).
- The association between persistent inflammation and IHD in CAPD patients requires further investigation.
Purpose of the Study:
- To evaluate the association between persistent elevation of C-reactive protein (CRP) and the presence or severity of ischemic heart disease (IHD).
- To determine if persistent CRP elevation is a predictor of IHD in patients on CAPD.
- To assess the utility of CRP as a screening marker for IHD in this patient population.
Main Methods:
- Seventy-three patients over 40 years old on CAPD were enrolled and followed for over 1 year.
- Plasma CRP levels were measured every 3 months; persistent elevation was defined as CRP ≥ 5 mg/L for > 6 months.
- Dipyridamole thallium single-photon emission computed tomography (SPECT) was used to assess for IHD; coronary angiography was performed in select patients.
Main Results:
- Twenty-six patients (35.6%) had persistent elevation of CRP.
- Seventeen of these 26 patients (65%) with persistent CRP elevation showed positive thallium SPECT findings for IHD.
- Multivariate logistic regression identified persistent CRP elevation as the sole significant predictor of positive thallium SPECT (P = 0.002).
Conclusions:
- Persistent elevation of C-reactive protein is strongly associated with the presence of ischemic heart disease in patients undergoing continuous ambulatory peritoneal dialysis.
- A persistent CRP elevation in CAPD patients, even without apparent cause, warrants investigation for IHD or other atherosclerotic vascular disease.
- CRP may serve as a valuable, non-invasive marker for identifying CAPD patients at high risk for IHD.
Abstract:
We evaluated the association between a persistent elevation of C-reactive protein (CRP) level and the presence or severity of ischemic heart disease (IHD) in patients with continuous ambulatory peritoneal dialysis (CAPD). Seventy-three patients, who were over 40 years old, underwent dipyridamole thallium single photon emission computed tomography (SPECT), and followed-up for more than 1 year were enrolled. We measured stored plasma for CRP every 3 months. Elevation of CRP was defined as greater than or equal to 5 mg/L and persistent elevation of CRP as elevated CRP levels that lasted longer than 6 months. Serum albumin, cholesterol, lipoprotein(a), and plasma fibrinogen were measured at 3 months after the start of CAPD. Twenty-six patients showed an elevation of CRP for more than 6 months during the follow-up period. Twenty-eight patients showed positive findings on thallium SPECT. Coronary angiography showed significant stenosis (narrowing of the diameter more than 50%) in 23 of the 25 patients studied. Seventeen (65%) of 26 patients who had an elevated CRP level for longer than 6 months had positive thallium SPECT. The presence of diabetes, albumin, fibrinogen, and the presence of a persistent elevation of CRP were different between the patients with positive (n = 28) or negative thallium SPECT (n = 45). A multivariate logistic regression analysis showed that a persistent elevation of CRP is the only predictor of positive thallium SPECT (P = 0.002). There was a tendency of association, although it was not statistically significant, between the persistence of CRP elevation and the severity of IHD (P = 0.066). Three of 9 patients who had a persistent elevation of CRP and a negative thallium SPECT had a history of cerebral infarction or peripheral vascular disease. Therefore, 77% (20/26) of an elevated CRP level that lasted longer than 6 months can be explained by the presence of IHD or other atherosclerotic vascular disease. In conclusion, a persistent elevation of CRP level in patients with CAPD was strongly associated with IHD. For patients who have a persistent elevation of CRP without an apparent cause, we recommend a workup for IHD or other atherosclerotic cardiovascular disease.