大腿四頭筋筋力と慢性心不全の死亡率

今日は抄録ですが日本人の発表なので、大腿四頭筋筋力と慢性心不全の死亡率の関連をみた報告を紹介します。

Kentaro Kamiya; Takashi Masuda; Atsuhiko Matsunaga; Kazumasa Miida; Misao N Ogura; Masahiko Kimura; Chiharu Noda; Minako Ymaoka-Tojo; Takayuki Inomata; Tohru Izumi. Decreased Strength of Quadriceps Increases the Risk of Mortality in Patients with Chronic Heart Failure. Circulation. 2010;122:A12709

http://circ.ahajournals.org/cgi/content/meeting_abstract/122/21_MeetingAbstracts/A12709

結論としては大腿四頭筋筋力が30%BWより低い（要するに筋力が弱い）場合には、40%BW（筋力がある）の場合と比べて死亡率がかなり高くなるという報告です。大腿四頭筋筋力が30%BWより低い慢性心不全患者の、2年間の死亡率は51％でした。

抄録では今回の慢性心不全患者がサルコペニアや悪液質、前悪液質の診断基準に該当するのかどうかは不明ですし、サンプルサイズも大きいとは言えませんが、大腿四頭筋筋力と慢性心不全の死亡率に関連はありそうです。全身の筋肉量、筋力を維持することの重要性を再確認しました。もっとも維持が容易ではありませんが…。

Background: Although cardiac cachexia is characterized by an exaggerated loss of skeletal muscle mass and muscle weakness, the diagnostic value of its muscle weakness was still undetermined. The purpose of this study was to investigate the relationship between quadriceps strength and cardiovascular mortality in patients with chronic heart failure (CHF) and to clarify the level of quadriceps strength that indicates a poor prognosis.

Methods: The isometric muscle strength of quadriceps was prospectively measured at the hospital discharge in 90 consecutive CHF patients, 63 males and 27 females aged 67.9 ± 12.6 yrs, which was expressed as % body weight (%BW). Cardiovascular mortality was analyzed with a Cox proportional-hazards models based on cardiovascular risk factors including age, medications, brain natriuretic peptide, estimated glomerular filtration rate and left ventricular ejection fraction.

Results: During the follow-up period of 340±240 days, 9 patients died of cardiovascular events. The relation between quadriceps strength and event free survival rate is shown in Figure. Patients who had lower quadriceps strength had significantly lower survival, and their mortality risk was increased by 2.67-fold per 10 %BW decrease (95% confidence interval: 1.06 to 6.67, P<0.05). Patients with <30%BW of quadriceps strength had a 12.85-fold higher mortality risk as compared with those with 40%BW. The two-year mortality rate indicated by quadriceps strength of <30%BW was 51%.

Conclusion: A Quadriceps strength of <30%BW indicated a poor prognosis in patients with CHF.