冠狀動脈繞道手術後心房顫動的研究

Abstract

背景: 心房顫動是冠狀動脈繞道手術後最常見心律不整的併發症。關於術後發生的心房顫動,目前其病生理機轉尚未明暸,促成因素也未確定,雖然術後房顫且不太影響手術短期的豫後或長期的追蹤,大部分的病人在二至三天後回復正常心律,但是如果發生在左心室功能不全的病人,易發生血液動力學不穩定的現象,也有可能因房顫的持續而延長住院天數。處理術後房顫,可以是預防或治療,而治療又可分心速控制或心律重整,在心臟功能穩定的情況下,並沒有最佳的治療方式。至於手術前後的預防,各種方法,葯物處方,也只有一定的效果。本研究藉由文獻的回顧及對冠狀動脈繞道手術後病人的追蹤及病歷察巡,以探討術後房顫的危險因子,葯物治療的方法及結果,及術後房顫病人的追縱及豫後。 方法: 本研究收集從1999 年5月至2006年12月間於中山醫學大學附設醫院接受冠狀動脈繞道手術的連續病人群,排除術前已是心房顫動的病人,同時接受其它開心手術如瓣膜置換等的病人亦排除在外,總共250人。冠狀動脈繞道手術的方法包括傳統手術,即使用體外循環機及心臟麻痺液,及不使用體外循環機的心臟不停跳手術(off-pump coronary artery bypass, OPCAB),包括迷你冠狀動脈繞道手術(minimally invasive direct coronary artery bypass, MIDCAB)。嘗試將危險因子依房顫形成要件,分成誘發因子,本質因素,及調節因子來分析。研究中使用Amiodarone來治療,評估Amiodarone的治療效果,並依Amiodarone的治療反應分成三種類別,第一類為立即反應者,第二類為再次發生者,第三類為延後反應者。最後對病人的術後追縱,其缺氧病兆,中風機率,及發生永久房顫的傾向。 結果: 27%的病人發生術後房顫,平均在術後2.4天。 術後房顫組和正常心律組的人口統計分析並無差異。在危險因子方面,並沒有顯著的誘發因子造成術後房顫。在本質因子中, 年齡 (odds ratio 1.057,95%信賴區間1.024至1.090),男性(odds ratio 1.921,95%信賴區間1.019至3.621),及術前有發生過心房不整脈者(odds ratio 13.435,95%信賴區間2.598至69.488),是影響術後房顫的主要因素。而調節因子中, 病人術前使用乙型阻斷劑可降低術後房顫的風險(odds ratio 0.511,95%信賴區間0.274至0.954),而服用Amiodarone則是明顯增加風險(odds ratio 4.563,95%信賴區間1.222至17.038),但以回歸分析後這兩個變數呈現不明顯。在房顫的處置方面,立即反應者約佔39.7%,再次發生者佔29.4%,延遲反應者佔30.9%。79.4%的房顫持續不到24小時,所有的病人在出院時都是正常竇性心率,有兩個病人(2.94%)因為持續靜脈點滴Amiodarone發生心博過慢而需停葯,或使用Isoprotereno1(Isuprel)。並沒有病人發生房顫的併發症如中風,或其他動脈栓塞等。住院天數在術後房顫組與正常心律組間或在對於Amiodarone治療不同反應的三類病人之間並無顯著差異。再次復發者,在年齡,性別及術前是否有過心房心率不整脈有統計上的意義,年齡大於70,其odds ratio 13.183,95%信賴區間2.428至71.577,女性其odds ratio 0.227,95%信賴區間0.056至0.923,而術前不整脈則odds ratio 為8.264,95%信賴區間1.175至58.143。在術後追綜方面, 發生術後房顫的病人,在死亡率,NYHA分類,心臟缺氧,及中風的發生,並沒有明顯差異,而在產生永久性房顫方面則是有顯著的意義。有3個病人得到永久性房顫,這三人均是手術後有暫時性房顫發生者。 結論: 術後房顫在冠狀動脈繞道手術中是屬於較常見但較良性的併發症,在危險因子方面,年齡及術前心房不整脈是目前所有的研究中,比較固定的影響因子。乙型阻斷劑的使用則是比較重要的調節因子。以Amiodarone來治療術後房顫,可以達到可接受的效果,同時並不會增加住院天數。發生術後房顫的病人,並不會影響繞道手術本身的豫後,但是可能是發生永久性房顫的徵兆。

Atrial fibrillation (Af) is the most common postoperative arrhythmic complication in patients undergoing coronary artery bypass grafting. The pathophysiological mechanism underlying the postoperative Af is not clearly understood. Although postoperative Af is generally considered to be paroxysmal and harmless, it may compromise hemodynamic conditions in patients with left ventricular dysfunction and possibly increases the risks of cerebrovascular accidents. Its prevention remains suboptimal and the rhythm disturbance itself is sometimes attributed to prolonged hospital stay and increased cost associated with Af. This study aims to evaluate clinical predictors of postoperative Af, the treatment effects of Amiodarone, and the prognosis of the patients with postoperative Af. Methods: Patients undergoing simple CABG in the absence of permanent Af (n = 250, between May 1999 and Dec. 2006) were recruited to the present case-control study. The techniques of CABG included on-pump arrest CABG, off-pump coronary artery bypass (OPCAB), and minimally invasive direct coronary bypass surgery (MIDCAB). The clinical risk factors were evaluated according to the triggers, the substance, and the modulators, which constitute the elements of atrial fibrillation. Patients who developed postoperative Af was treated with intravenous Amiodarone injection. The responders were identified as three groups: the immediate responders, recurrent Af and delayed responders. Further evaluations were made between the three groups. All the patients were followed up postoperatively after discharge from the hospital for ischemic events, fatal events, CVA and the incidence of permanent Af. Results: The incidence of postoperative Af in this study was 27%. Most of the AF occurred 1-3 day postoperatively (mean 2.4 days). The demographic data between the Af patients and NSR patients was comparable. In the analysis of risk factors, there were no statistically significant triggers related to postoperative Af. Logistic regression identified age (OR 1.057, 95% CI 1.057-1.090),male (OR 1.921,95% CI 1.019-3.621),and preoperative atrial arrhythmia (OR 13.435,95% CI 2.598-69.488) as major risk factors. As for the modulators, beta blockers taken preoperatively could lower the incidence of Af (OR 0.511,95% CI 0.274-0.954), while Amiodarone paradoxically increased the incidence of af (OR 4.563,95% CI 1.222-17.038). Both factors became obscure once entered the logistic regression. Amiodarone injection converted 79.4% Af to NSR within 24 hours. Two patients (2.94%) had bradycardia and needed to hold the drug or started Isoproterenol i.v. infusion. 39.7% patients got immediate response and regained NSR. In 29.4% patients, Af recurred and need another injections or continuous infusion.30.9% patients did not respond to the first injections and regained NSR after continuous i.v. infusion for some time. In the recurrent group, age, sex and preoperative atrial arrhythmia seemed to be significant risk factors, with age>70 OR 13.183,95% CI 2.428-71.577,female OR 0.227,95% CI 0.056-0.923,and atrial arrhythmia OR 8.264,95% CI 1.175-58.143. Significantly 3 patients contracted permanent Af late during follow up. Otherwise, postoperative Af did not affected CABG prognosis. The ischemic events, the fatal events and the incidence of CVA did not make significant differences between those who remained sinus rhythm postoperatively and those who did not. Conclusions: Postoperative Af is a common and benign complication after coronary bypass surgery. Advancing age and preoperative atrial arrhythmia seemed to be the most powerful contributing risk factors. Beta blocker remained the significant modulator. Although there are newer antiarrhythmic agents for the treatment or prevention of Af, Amiodarone could be used for postoperative Af in CABG with acceptable conversion rates and minimum complications. In usual conditions, it does not increase hospital stay and thus hospital cost. The mere occurrence of postoperative Af is not related to the prognosis of CABG. But there is chance that postoperative Af may predispose to permanent Af.