左支束傳導阻滯病人的臨床預後及T波型態分析

Abstract

背景與目標：左支束傳導阻滯是由心電圖診斷出的一種心臟電氣傳導障礙，過去研究顯示此阻滯可能會引起不同步的心室收縮，進而導致心臟衰竭。目前發現慢性腎臟病也和心臟電氣傳導阻滯有關，更是造成心臟衰竭的重要因子。在合併心臟衰竭的左支束傳導阻滯病人中，使用心臟再同步治療可來改善病人存活率及生活品質，但是此項手術仍有相當比例的不反應者。在台灣，探討左支束傳導阻滯病人的盛行率及預後並未被詳細地研究。本研究的目標為: 探討(1)左支束傳導阻滯在各年齡層之間分布，與左心室射出分率的相關性; (2)了解左支束傳導阻滯且左心室射出分率正常病人的預後；(3) 慢性腎臟病對於左支束傳導阻滯病人的預後影響；(4)評估以T波型態分析法來預測心臟再同步治療反應率。 方法：本研究利用台大醫院資料庫找出在2010年到2013年中有164,049位病人做過心電圖檢查，我們找出其中心電圖為左支束傳導阻滯的病人，1) 分析左支束傳導阻滯在各年齡層的盛行率及和心室射出分率的相關性;另外針對規則於院內追蹤的左支束傳導阻滯病人，收集病患的過去病史、檢驗報告，心臟超音波報告及用藥情形，病例或電話追蹤病人的心臟衰竭住院發生情形及死亡率2) 再找出一組年紀，性別匹配且左心室射出分率正常的對照組比較; 3)分析慢性腎臟病對於左支束傳導阻滯病人預後的影響; 4)施行T波型態分析法，探討T波型態分析因子與收縮功能不全心臟衰竭的相關性及用來評估心臟再同步治療反應率的效用。 結果：在台灣，左支束傳導阻滯病人的盛行率為0.4%，其中有56%其左心室射出分率為正常。但是在左心室射出分率正常的病人，左支束傳導阻滯會有較高的心因性死亡，較高的心臟衰竭再住院率。慢性腎臟病是造成左支束傳導阻滯病人死亡的重要危險因子。利用Ｔ波型態分析法得出的Ｔ波型態因子來分析心臟再極化異質性，我們發現包括Ｔ波型態因子中可看出心臟再極化異質性越大，和收縮功能不全心臟衰竭(左心室射出分率<40%)有相關性，另外針對置放心臟再同步治療病人，心臟再極化異質性較大的病人也有較高的心臟再同步治療反應率。 結論：和國外資料相比，在台灣的左支束傳導阻滯病人有較高的比例其左心室射出分率為正常(左心室射出分率>50%)，這可部分解釋為什麼在台灣置放心臟再同步治療的比例低於歐美國家。在左心室射出分率正常且無心房顫動病史的病人中，有左支束傳導阻滯病人仍有較高的心因性死亡，及心臟衰竭再住院率。慢性腎臟病是造成左支束傳導阻滯病人死亡的危險因子。利用Ｔ波型態分析法得出的Ｔ波型態因子來反應心臟再極化異質性，為偵測心臟再同步治療反應率的有效預測因子。

Background: Complete left bundle branch block (cLBBB), an electrical conduction abnormality, may harm the left ventricular (LV) mechanical synchrony and lead to heart failure. Chronic kidney disease (CKD) is a strong risk factor for heart failure and associated with conduction abnormality. Cardiac resynchronization therapy (CRT) improves survival of patients with cLBBB and systolic heart failure. Approximately 40% of recipients, however, do not show significant clinical responses. In Taiwan, the prevalence and prognosis in patients with cLBBB have not been properly investigated. Objectives of our study therefore, were (1) to estimate the prevalence of cLBBB in Taiwan; (2) to understand the impact of cLBBB on patients with normal left ventricle (LV) ejection fraction (EF); (3) to evaluate the risk of mortality associated with CKD in patients with cLBBB; (4) to evaluate the association between ventricular repolarization heterogeneity and LV systolic dysfunction using T-wave morphology analysis method and the prognostic value of T-wave morphology parameters in CRT response. Method: We enrolled 164,049 patients who underwent a standard 12-lead electrocardiography (ECG) between January 2010 and December 2013 at the National Taiwan University Hospital, First, the prevalence of cLBBB was calculated. Adult patients with regular follow-up were included in the study. Baseline characteristics, blood serum reports, echocardiographic reports, and cardiovascular medication use were reviewed from the medical chart. Furthermore, events like heart failure admission and death were either reviewed from the medical chart or via phone. Next, we matched patients without conduction abnormalities and with normal LVEF according to age and sex. The risk of CKD in patients with cLBBB was subsequently evaluated, and a T-wave morphology analysis was also used to evaluate the association between T-wave morphology parameters and LVEF. Result: The prevalence of cLBBB was 0.4%, and 56% of patients had a normal EF. The rate of patients between the ages of 40 to 60 years with an EF of less than 35%, was 45%. Patients with cLBBB and normal EF, but without a history of atrial fibrillation, had a significantly higher risk of CV mortality, EF reduction to 40%, and admission for heart failure (HF). CKD is an independent risk factor for total mortality, while increased T-wave morphology parameters like T-wave morphology dispersion (TMD) and larger T-wave morphology residuum (TWR) were all associated with LVEF < 40%. A large TMD and high T-wave loop area (PL) were also independent predictors of the clinical CRT response outcome endpoint. Conclusion: Patients in Taiwan had a low prevalence of cLBBB and LVEF < 35%. This may partially explain the low implantation rate of CRT devices in patients with HF in Taiwan compared with western countries. In patients with normal EF and without a history of atrial fibrillation, the presence of cLBBB is an important risk factor for CV mortality and HF admission. CKD was an independent risk factor for total mortality in patients with cLBBB. Increases in repolarization heterogeneity in patients with cLBBB are associated with impaired LVEF and may be useful as additional predictors of response to CRT, and improving patient selection for CRT.