アルブミン値は心不全患者の生存予後因子

アルブミン値は心駆出率の保たれた心不全患者の生存を予測する研究を紹介します。

Ming Liu, et al: Albumin levels predict survival in patients with heart failure and preserved ejection fraction. Eur J Heart Fail (2011) doi: 10.1093/eurjhf/hfr154

心駆出率の保たれた（左室駆出率50%以上）心不全の入院患者（以下、HFPEF）576人を対象に、入院後早期の血清アルブミン値と1年後の予後を調査しました。低アルブミン血症（3.4g/dl以下）は160人（28%）に認め、低アルブミン血症群と正常アルブミン血症群に分類して検討しました。

低アルブミン血症群では、慢性腎不全の有病割合、クレアチニン、尿素窒素が有意に高く、生存率が有意に悪く（53％対84%）、心血管死が有意に多い（21.8%対8.9%）という結果でした。多変量解析では、低アルブミン血症、心血管疾患の既往、高齢が1年後の死亡率の独立した予後因子でした。

以上より、HFPEF患者では低アルブミン血症をよく認め、低アルブミン血症の場合に死亡率が高く、この病態に腎機能障害が関与している可能性があるという結論です。

低アルブミン血症では心不全患者の予後が悪いというのは以前のレビューでも紹介しました。心腎連関や悪液質が予後に関与している可能性が疑われます。もちろん低栄養で低アルブミン血症となり、低栄養が予後に関与している要素もありますが、アルブミン値は栄養指標より予後指標と考えるべきです。

Abstract
Aims Low serum albumin is common in patients with systolic heart failure and is associated with increased mortality. However, the relationship between albumin and outcome in patients with heart failure and preserved ejection fraction (HFPEF) is not known. The aim of this study was to investigate the effect of serum albumin level on survival in patients with HFPEF.

Methods and results We studied 576 consecutive HFPEF patients (left ventricular ejection fraction ≥50%) admitted to our hospital from 2006 to 2009. Standard demographics, transthoracic echocardiography, and routine blood testing including albumin levels were obtained shortly after admission. Outcome was assessed at 1 year after admission. Hypoalbuminaemia (≤34 g/L) was detected in 160 (28%) at admission; and all patients were then divided into hypoalbuminaemia and non-hypoalbuminaemia groups. In the hypoalbuminaemia group, the prevalence of chronic renal failure history, serum creatinine, and urea nitrogen levels were higher when compared with those without hypoalbuminaemia (all P < 0.05). Kaplan–Meier analysis showed that patients with hypoalbuminaemia had a significantly lower survival rate (53% vs. 84%, log-rank χ2 = 53.3, P < 0.001) and a higher rate of cardiovascular death (21.8% vs. 8.9%, log-rank χ2 = 19.7, P < 0.001) when compared with those without hypoalbuminaemia. Cox regression further revealed that hypoalbuminaemia, a history of cerebrovascular disease, and older age were the most powerful independent predictors of all-cause mortality in HFPEF patients at 1 year.

Conclusions Hypoalbuminaemia is common in HFPEF patients and is associated with increased risk of death. Renal dysfunction may be the main pathophysiological mechanism underlying hypoalbuminaemia in HFPEF patients.