2nd Department of Cardiology and Electrotherapy, Medical University of Gdansk, ul. Dębinki 7, Gdańsk, Poland.
Kardiol Pol. 2012;70(8):795-802.
Microvolt T-wave alternans (MTWA) is a recommended noninvasive diagnostic test for predicting the risk of sudden cardiac death (SCD). However, about 6% to 41% of MTWA results are indeterminate. The causes, interpretation and clinical significance of these results have not been not clearly established.
To assess frequency, causes, and prognostic significance of indeterminate MTWA results in a group of patients with left ventricular dysfunction referred for implantable cardioverter-defibrillator (ICD) placement in the primary prevention of SCD.
Patients with left ventricular ejection fraction (LVEF) ≤ 35% underwent MTWA evaluation during a treadmill exercise test (CH2000 system, Cambridge Heart Inc. Bedford MA, USA). MTWA results (spectral analysis) were categorised as positive, negative, or indeterminate (MTWApos, MTWAneg, and MTWAnd, respectively). Patients were followed up for the occurrence of SCD, ventricular tachycardia (VT), and ventricular fibrillation (VF).
Mean age of participants (n = 93) was 63 ± 13 years, an ischaemic cause of left ventricular dysfunction was present in 70 (75%) patients, and average LVEF was 30 ± 7%. MTWApos was found in 27 (29%) patients, MTWAneg in 41 (44%) patients, and MTWAnd in 25 (27%) patients. Causes of MTWAnd included inability to achieve a diagnostic HR in 12 (48%) patients, ventricular ectopy in 5 (20%) patients, nonsustained alternans in 3 (12%) patients, and technical factors (artifacts due to a high noise level) in 5 patients (20% of indeterminate results, 5.4% of the whole study group). During follow-up, 8 SCD/VT/VF events were noted (4 patients with MTWApos and 4 patients with MTWAnd due to patient-related factors). The rate of SCD/VT/VF was 35% in patients with MTWApos and 34.6% in MTWAnd due to patients-related factors, significantly higher compared to those with MTWAneg or MTWAnd due to technical factors (p 〈 0.05).
Although the proportion of indeterminate MTWA results in patients with left ventricular dysfunction referred for ICD implantation in the primary prevention of SCD was high, the proportion of indeterminate MTWA results due to technical factors, probably of no prognostic significance, was small.
微伏 T 波交替（MTWA）是一种推荐的无创诊断测试，用于预测心脏性猝死（SCD）的风险。然而，约有 6%至 41%的 MTWA 结果不确定。这些结果的原因、解释和临床意义尚未明确。
评估左心室功能障碍患者群体中植入式心脏复律除颤器（ICD）用于 SCD 一级预防时 MTWA 不确定结果的频率、原因和预后意义。
左心室射血分数（LVEF）≤35%的患者在跑步机运动试验（CH2000 系统，马萨诸塞州贝德福德的剑桥心脏公司）期间进行 MTWA 评估。MTWA 结果（频谱分析）分为阳性、阴性和不确定（MTWApos、MTWAneg 和 MTWAnd）。对患者进行 SCD、室性心动过速（VT）和心室颤动（VF）发生的随访。
参与者（n=93）的平均年龄为 63±13 岁，70 例（75%）患者存在缺血性左心室功能障碍，平均 LVEF 为 30±7%。MTWApos 见于 27 例（29%）患者，MTWAneg 见于 41 例（44%）患者，MTWAnd 见于 25 例（27%）患者。MTWAnd 的原因包括 12 例（48%）患者无法达到诊断性 HR、5 例（20%）患者室性早搏、3 例（12%）患者非持续交替和 5 例（20%）患者技术因素（高噪声水平引起的伪影）。随访期间，共发生 8 例 SCD/VT/VF 事件（MTWApos 患者 4 例，因患者相关因素 MTWAnd 患者 4 例）。MTWApos 患者的 SCD/VT/VF 发生率为 35%，因患者相关因素 MTWAnd 的发生率为 34.6%，显著高于因技术因素 MTWAneg 或 MTWAnd（p〈0.05）。
尽管左心室功能障碍患者中 MTWA 不确定结果在 ICD 植入一级预防 SCD 中所占比例较高，但可能无预后意义的技术因素导致的 MTWA 不确定结果比例较小。
