Kulakowski P, Counihan P J, Camm A J, McKenna W J
Department of Cardiological Sciences, St George's Hospital Medical School, London, U.K.
Eur Heart J. 1993 Jul;14(7):941-50. doi: 10.1093/eurheartj/14.7.941.
Late potentials detected by the signal-averaged ECG (SAECG) identify post-infarction patients at risk from sustained ventricular tachycardia (VT) and sudden death. Hypertrophic cardiomyopathy (HCM) is also associated with increased risk of sudden death. In adults, episodes of non-sustained VT on ambulatory ECG monitoring are a marker of high risk patients. In children and adolescents, however, there is no reliable ECG marker, and clinical features have low predictive accuracy. The prognostic value of the SAECG in HCM has not been systematically evaluated. We examined the relation of detailed time domain, frequency domain, and spectral temporal mapping analysis of the SAECG and clinical and echocardiographic features, and the results of 48 h ambulatory ECG monitoring in 121 consecutive patients with HCM. Non-sustained VT on Holter monitoring was recorded in 27 (23%) patients. An abnormal time domain SAECG was present in three (11%) patients with VT vs three (3%) without VT (ns). Of the SAECG variables, reduced (below 150 microV) voltage of the initial 40 ms of the signal-averaged QRS complex was the best predictor for non-sustained VT (sensitivity: 95%; specificity: 74%: positive predictive accuracy: 64%; negative predictive accuracy: 97%). Nine patients (of whom eight were < or = 30 years of age) experienced catastrophic events: three died suddenly and six had been resuscitated from out-of-hospital ventricular fibrillation. None of them had an abnormal time domain SAECG. The frequency domain analysis and spectral temporal mapping of the SAECG did not improve the identification of patients with VT or patients with catastrophic events. In conclusion, alterations of the initial portion of the signal-averaged QRS complex identified patients with HCM and non-sustained VT, but the SAECG was not useful in identifying young patients who suffered cardiac arrest.
信号平均心电图（SAECG）检测到的晚电位可识别出有持续性室性心动过速（VT）和猝死风险的心肌梗死后患者。肥厚型心肌病（HCM）也与猝死风险增加相关。在成年人中，动态心电图监测发现的非持续性VT发作是高危患者的一个标志。然而，在儿童和青少年中，没有可靠的心电图标志，且临床特征的预测准确性较低。SAECG在HCM中的预后价值尚未得到系统评估。我们研究了121例连续HCM患者的SAECG详细时域、频域和频谱时间映射分析与临床及超声心动图特征的关系，以及48小时动态心电图监测结果。27例（23%）患者在动态心电图监测中记录到非持续性VT。3例（11%）发生VT的患者存在异常时域SAECG，而3例（3%）未发生VT的患者也存在异常时域SAECG（无显著性差异）。在SAECG变量中，信号平均QRS波群初始40毫秒的电压降低（低于150微伏）是预测非持续性VT的最佳指标（敏感性：95%；特异性：74%；阳性预测准确性：64%；阴性预测准确性：97%）。9例患者（其中8例年龄≤30岁）发生灾难性事件：3例猝死，6例经院外心室颤动复苏成功。他们均无异常时域SAECG。SAECG的频域分析和频谱时间映射并未改善对VT患者或发生灾难性事件患者的识别。总之，信号平均QRS波群初始部分的改变可识别出患有HCM和非持续性VT的患者，但SAECG对识别发生心脏骤停的年轻患者并无帮助。
