Prognostic implications of anemia with or without chronic kidney disease in patients undergoing elective percutaneous coronary intervention

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Abstract

Background

Little is known about the prognostic implications of anemia in patients undergoing elective percutaneous coronary intervention (PCI), especially when they have coexisting chronic kidney disease (CKD).

Methods

We identified 7299 patients who underwent elective PCI from the CREDO-Kyoto registry cohort-2. The primary outcome was 3-year major adverse cardiac events (MACE); composite of all cause death, heart failure hospitalization, and myocardial infarction.

Results

In total, 1466 patients (20.0%) had mild anemia (hemoglobin = 11.0–11.9 g/dL for women and 11.0–12.9 g/dL for men), and 740 patients (10.1%) had moderate-to-severe anemia (hemoglobin < 11.0 g/dL both for women and for men). Compared to the no-anemia group, cumulative incidence of MACE was significantly higher in the mild and moderate-to-severe anemia groups (7.9%, 20.1%, and 34.2%, respectively). The adjusted hazard ratios of mild and moderate-to-severe anemia versus no-anemia for MACE were 1.77 (95% confidence interval: 1.47–2.15) and 2.53 (95% confidence interval: 2.03–3.14), respectively. In a subgroup analysis, significantly higher risk for MACE was consistently observed with mild and moderate-to-severe anemia both in patients with and without CKD. The risk for MACE showed an accretive increment with exacerbation in either the renal function or anemia (interaction p < 0.001).

Conclusions

Even mild anemia was associated with significantly worse 3-year clinical outcomes in patients who underwent elective PCI. Coexisting CKD additively increased the risk for MACE in these patients.

Introduction

Anemia is a common comorbidity in patients with coronary artery disease (CAD) [1]. Its prevalence increases with disease severity as a consequence of associated disorders such as chronic kidney disease (CKD), iron deficiency, malnutrition and cancer-related blood losses [2]. Anemia may increase the risk of cardiovascular events by inducing myocardial ischemia [3], congestive heart failure [4], or by contributing to high residual platelet activity on clopidogrel [5]. Recent cohort studies have reported worse clinical outcomes among anemic patients undergoing percutaneous coronary intervention (PCI) [6], [7], [8]. However, the hemoglobin (Hb) level that may affect cardiovascular outcomes and whether the presence of CKD influences the outcomes in these patients remain obscure. Moreover, little data is available regarding the impact of anemia on prognosis in patients undergoing elective PCI. In the present study, we investigated the relationship between severity of anemia, CKD, and clinical outcomes in patients who underwent elective PCI, analyzing data from a multicenter registry in Japan.

Section snippets

Study design and patient population

We included the study patients from the CREDO-Kyoto registry cohort-2. The design and patient enrollment of the CREDO-Kyoto registry cohort-2 has been previously described [9]. In brief, the CREDO-Kyoto registry cohort-2 is a physician-initiated non-company sponsored multi-center registry enrolling consecutive patients who underwent first coronary revascularization in 26 centers in Japan between January 2005 and December 2007 (Supplemental Appendix A). Among 15,263 patients enrolled in the

Baseline characteristics

Anemia was observed in 2206 patients (30.2% of the study population) composed of mild anemia (n = 1466, 20.1%) and moderate-to-severe anemia (n = 740, 10.1%) (Table 1). Compared to patients in the no-anemia group, patients in the anemia groups were older, likely to be female, and had more comorbidities such as CKD, hypertension, diabetes mellitus, thrombocytopenia, and malignancy. Cardiovascular complications such as prior myocardial infarction (MI), prior stroke, peripheral vascular disease, heart

Discussion

In this large cohort of 7299 patients undergoing elective PCI, (1) anemia was observed in as many as 2206 patients (30.2% of the entire study population), composed of 1466 patients with mild anemia (20.1%) and 740 patients with moderate-to-severe anemia (10.1%), (2) anemic patients had more comorbidities such as CKD, advanced age, hypertension, diabetes mellitus, malignancy, and cardiovascular complications, (3) both mild and moderate-to-severe anemia were associated with worse long-term

Conclusions

Anemia was significantly associated with worse 3-year clinical outcomes in patients undergoing elective PCI. According to the WHO definition of anemia, even mild anemia was significantly associated with the risk for MACE. Coexisting CKD additively increased the risk for MACE in these patients.

Acknowledgments

This study was supported by the Pharmaceuticals and Medical Devices Agency (PMDA) in Japan. We appreciate the support and collaboration of the co-investigators participating in the CREDO-Kyoto PCI/CABG registry cohort-2. We are indebted to the outstanding effort of the clinical research coordinators for data collection. We also thank Tomás Romero, MD, Associate Clinical Professor, University of California, San Diego, for his advice in the review and editing the manuscript.

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