腎功能及特定HF藥物使用可用來預測CRT-D患者死亡率


  May 11, 2005 (紐奧良) - 在心律研究協會(HRS)第26屆年會上,研究人員表示,以植入去顫器的方式作心臟再同步化治療後(CRT-D),不良的腎功能、未使用特定的心臟衰竭治療藥物等狀況,可有效的用來預測早期及長期的死亡率。
  
  這是一項回顧性分析研究,資料期長達7年,患者來自一名為CONTAK CD的臨床試驗計畫;研究人員發現,腎功能的降低,未使用乙型阻斷劑,未使用血管張力素轉換酵素抑制劑(ACE),使用利尿劑,及較高的心臟衰竭風險等,皆可以用來預測長期的死亡率;正常體重的患者,若顯示出較高的血清尿氮濃度,且未使用ACE抑制劑,會有較高的短期死亡率(植入手術後兩年內)。
  
  研究人員指出,腎功能及未使用到特定的心衰竭藥物,可以充分的預測CRT-D患者的早期及長期死亡率;因為缺少長期的試驗對照組,因此這些研究發現還需要更進一步的試驗始得證實。
  
  HRS計畫的主持人Dwight Reynolds醫師表示,對於這一類患者,本項研究基本上證實了不良腎功能的象徵性,也確認了正確心衰竭藥物的重要性;但是,也可能是某些患者對於一些心衰竭藥物具有禁忌。
  
  研究的資料蒐集自CONTAK CD的登錄資料庫中,包括了501位CRT-D患者;其間,研究人員對36個基線因子的影響進行評估,這些因子含年齡、體型大小、病原學、心衰竭藥的的使用、腎功能,及所有與心臟測量有關的長短期致死原因等;在研究期間內,501位患者中,有51%死亡,26%在初期兩年內面臨瀕死狀況,平均的存活期為4.7年。
  
  根據研究人員發現,血清尿氮濃度超過24 mg/dL者,早期的死亡風險為濃度較低者的3.8倍;同樣的,患者的單位面積體重低於27 kg/m2者,風險為2.8倍;屬於紐約心臟協會第III/IV級的患者,早期死亡風險為等級較低者的2.4倍。
  
  其他的風險因子,如未使用ACE抑制劑及乙型阻斷劑者,死亡風險為使用者的2.3倍;因缺血而導致心衰竭,使用非循環性的利尿劑等,會提升幾乎2倍的死亡風險。
  
  至於血清尿氮濃度,研究人員發現,濃度超過24mg/dL者,長期的死亡率是較低者的兩倍;腎小球濾過率(GFR)超過64 mL/分/1.73m2者,死亡率會超過較低者1.6倍;未使用ACE抑制劑及乙型阻斷劑,死亡率會增加1.8倍;非循環性利尿劑的使用,會將死亡率提升1.7倍。
  
  Patrick Young, MSEE是一名臨床研究顧問,受雇於Guidant Corp公司,他在會議中以海報的方式作發表;他表示,本研究著重在探討這些患者的長期死亡率;短期死亡率的預測因子會和長期相似,這些因子含腎功能的降低,未使用乙型阻斷劑及血管張力素轉換酵素抑制劑(ACE)的合併藥物,及使用非循環利尿劑等,皆會提升死亡風險。
  
  Young向Medscape表示,從1998年初起,這類的治療方式就已經有了改變;舉例而言,許多大型的研究都已經對乙型阻斷劑在這方面的效果作過證實;本研究的重點在於,探討ACE抑制劑及乙型阻斷劑的使用,或其中一項藥物在未被使用時,對患者會造成何種影響;在1998年,很多醫師不開立乙型阻斷劑的處方,但今天,大部分都已經這麼做了;醫療方式在持續的改變當中。
  
  Young進一步表示,本研究的某些發現或許可以作為另一種狀況的標記;例如,因為某些患者對乙型阻斷劑具有禁忌性,因此在某些情況下,患者之所以未受到某些藥物的處方,可能就代表著該藥物根本不可用於該患者。
  
  本研究由Guidant Corp公司及CONTAK CD贊助;後者為心臟再同步去顫器的製造者;Patrick Young受雇於前者。

Renal Function, Use of Certain

By
Medscape Medical News

May 11, 2005 (New Orleans) — Poor renal function and the nonuse of certain heart failure medications were powerful predictors of early and late mortality in patients receiving cardiac resynchronization therapy with a defibrillator (CRT-D), researchers reported here at the Heart Rhythm Society (HRS) 26th annual scientific sessions.

In a seven-year retrospective analysis of patients in the CONTAK CD trial, researchers found that reduced kidney function, the nonuse of beta-blocker and angiotensin-converting enzyme (ACE) inhibitor therapy, the use of diuretics, and a higher classification of heart failure were predictors of long-term mortality. Patients were at higher risk of short-term mortality (within two years after implant) if they had high levels of serum urea nitrogen, were normal weight, and did not take beta-blockers or ACE inhibitors.

"Renal function and the use or nonuse of certain heart failure drugs were powerful predictors of early and late mortality in these patients with CRT-D," the researchers reported. "Further study is required to confirm these findings since a long-term control group is not available."

"This study basically confirms the significance of renal dysfunction and the importance of adequate heart failure drugs in managing the patient," said Dwight Reynolds, MD, HRS program chairman, who wsa not involved in the study. "However, it could be that some of these patients had contraindications for the heart failure drugs."

Using data collected from 501 CRT-D patients enrolled in the CONTAK CD registry, the investigators assessed the influence of 36 baseline factors, including age, body size, etiology, heart failure medication use, renal function, and cardiac measurements on the rate of long-term and early all-cause mortality. During the study period, 51% of the 501 patients died, with 26% dying within the first two years. Median survival time was 4.7 years.

The investigators found that patients with serum urea nitrogen levels higher than 24 mg/dL had 3.8 times the risk of early mortality compared with patients with lower serum urea nitrogen levels. Similarly, patients who weighed less than 27 kg/m2 had 2.8 times the risk of early mortality, and those classified as New York Heart Association Class III/IV had 2.4 times the risk of early death compared with patients with lower classifications.

Other risk factors included not taking both ACE inhibitors and beta-blockers, which increased the risk of death by 2.3 times compared with those taking both heart failure medications. Heart failure of ischemic etiology and the use of nonloop diuretics were associated with almost twice the risk of death.

The researchers found that patients were twice as likely to die over the long term if they had serum urea nitrogen levels higher than 24 mg/dL compared with those with lower rates; they had a 1.6 increased risk of death if the glomerular filtration rate (GFR) was higher than 64 mL/minute/ 1.73 m2 compared with lower rates; they had 1.8 times the risk of dying if they were not taking both beta-blockers and ACE inhibitors, and 1.7 times the risk of death if they were taking nonloop diuretics.

"This study was a long-term look at mortality in these patients," Patrick Young, MSEE, a clinical research advisor from Guidant Corp. and the presenter of the poster. "The factors that predicted early death are similar to those that predict later death," he said. "Renal dysfunction, not taking a combination of ACE inhibitors and beta-blockers, and taking nonloop diuretics all increased the risk of dying."

Mr. Young told Medscape that medical practice has changed since the study began in early 1998. For example, several large studies have pointed out the importance of beta-blocker therapy in these patients. This study only looked at patients who either were taking both ACE inhibitors and beta-blockers or were not taking either drug, he said. "A lot of physicians weren't prescribing beta-blockers in 1998, but most are today. Medical practice is constantly changing."

Some of the findings might also serve as a marker for another underlying condition, Mr. Young said. For example, because beta-blockers are contraindicated in some patients, "in some respects, not taking a drug could be a marker for the reason the patient is not prescribed the drug."

The study was funded by Guidant Corp., the maker of CONTAK CD, a cardiac resynchronization therapy device. Patrick Young is an employee of Guidant.

HRS 26th Annual Scientific Sessions: Poster 87. Presented May 7, 2005.

Reviewed by Gary D. Vogin, MD

Linda Little is a freelance writer for Medscape.

    
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