Hrobon P, Kuntz K M, Hare J M
Harvard School of Public Health, Boston, Mass, USA.
J Heart Lung Transplant. 1998 May;17(5):479-86.
Performance of endomyocardial biopsy (EMB) to diagnose myocarditis in patients with dilated cardiomyopathy is controversial because of a lack of evidence favoring immunosuppressive therapy. In spite of advances in heart failure treatment, dilated cardiomyopathy carries a poor prognosis, and myocardial inflammation and viral infection are potential therapeutic targets.
We used decision analysis to determine the efficacy (5-year risk reduction in mortality or transplantation) that a treatment for myocarditis would require to favor a biopsy-guided approach over conventional therapy. Literature-based estimates included prevalence of myocarditis among patients with dilated cardiomyopathy with or without borderline myocarditis (16% and 11%, respectively); probability of 5-year transplantation-free survival (55%); sensitivity (50% and 63%, respectively), specificity (95.4%), and mortality rate (0.4%) of EMB; side effects resulting in withdrawal of immunosuppressive treatment (4%); and a 6-month mortality rate for immunosuppressive treatment (0.1%). All estimates were varied to determine impact on model results (sensitivity analysis).
A therapy that decreased the rate of death or transplantation by 12.7% and 7.1% for patients without or with borderline myocarditis, respectively, favored EMB. Sensitivity analysis indicated that therapeutic efficacy was influenced by myocarditis prevalence and biopsy-related death, but not by accuracy of biopsy or probability of immunosuppressive therapy side effects. Randomized trials powered to detect 7% and 25% reductions in death and transplantation would require 5790 and 380 end points, respectively.
Decreasing the rate of death or transplantation by 7.1% offsets therapy side effects, EMB-related death, and inaccuracies in histologic diagnosis. Prospective randomized trials of treatments for myocarditis may be more feasible during periods of high prevalence or with more sensitive diagnostic techniques.
由于缺乏支持免疫抑制治疗的证据，经心内膜心肌活检（EMB）诊断扩张型心肌病患者的心肌炎存在争议。尽管心力衰竭治疗取得了进展，但扩张型心肌病的预后仍然很差，心肌炎症和病毒感染是潜在的治疗靶点。
我们使用决策分析来确定心肌炎治疗需要达到何种疗效（5年死亡率或移植率降低），才能支持采用活检引导的方法而非传统治疗。基于文献的估计包括：伴有或不伴有临界性心肌炎的扩张型心肌病患者中心肌炎的患病率（分别为16%和11%）；5年无移植生存率（55%）；EMB的敏感性（分别为50%和63%）、特异性（95.4%）和死亡率（0.4%）；导致免疫抑制治疗中断的副作用（4%）；以及免疫抑制治疗的6个月死亡率（0.1%）。对所有估计值进行变化，以确定对模型结果的影响（敏感性分析）。
对于无临界性心肌炎和有临界性心肌炎的患者，分别将死亡或移植率降低12.7%和7.1%的治疗方法更倾向于EMB。敏感性分析表明，治疗效果受心肌炎患病率和活检相关死亡的影响，但不受活检准确性或免疫抑制治疗副作用概率的影响。为检测死亡和移植率分别降低7%和25%而进行的随机试验，分别需要5790个和380个终点。
将死亡或移植率降低7.1%可抵消治疗副作用、EMB相关死亡和组织学诊断的不准确性。在患病率较高或诊断技术更敏感的时期，开展心肌炎治疗的前瞻性随机试验可能更可行。
