Kumar Kapil, Kwaku Kevin F, Verrier Richard L
Beth Israel Deaconess Medical Center, Harvard Institutes of Medicine, 77 Avenue Louis Pasteur, Room 223, Boston, MA 02115, USA.
Curr Treat Options Cardiovasc Med. 2008 Feb;10(1):39-48. doi: 10.1007/s11936-008-0005-1.
Risk stratification for primary prevention of sudden cardiac death (SCD) remains a major challenge in cardiology. The utility of T-wave alternans (TWA) as a marker of risk of life-threatening ventricular tachycardia and fibrillation is supported by two decades of basic and clinical research. Both frequency- and time-domain methods have been developed, validated, and made available in clinical practice. A principal application of TWA testing has been to improve assessment of patients with depressed left ventricular ejection fraction (EF; </= 40%) who are considered for implantable cardioverter-defibrillator (ICD) implantation for primary prevention of SCD. TWA has been most useful in identifying patients who are unlikely to benefit from ICD therapy. Although patients with low EF should remain an important focus, the absolute number of SCD events is far greater among post-myocardial infarction patients with relatively preserved EF, even though the incidence of SCD in this population is low. Recent studies suggest that TWA testing is predictive in this population as well. Absolute quantification of TWA rather than binary classification into "normal" or "abnormal" appears to be valuable in more finely stratifying the magnitude of arrhythmic risk. Longitudinal testing may be warranted in certain populations, although the optimum interval remains to be determined. Combining TWA with noninvasive markers of autonomic function, such as heart rate turbulence, may further increase predictive accuracy. Future development will likely expand the role of TWA testing with routine exercise and ambulatory electrocardiographic monitoring to screen lower-risk populations and to guide medical and device-based therapy.
心脏性猝死（SCD）一级预防的风险分层仍是心脏病学领域的一项重大挑战。二十年来的基础和临床研究均支持将T波电交替（TWA）作为威胁生命的室性心动过速和颤动风险的标志物。频域和时域方法均已得到开发、验证并应用于临床实践。TWA检测的一个主要应用是改善对左心室射血分数（EF；≤40%）降低、考虑植入植入式心脏复律除颤器（ICD）进行SCD一级预防的患者的评估。TWA在识别不太可能从ICD治疗中获益的患者方面最为有用。虽然EF低的患者应始终是重要关注对象，但在EF相对保留的心肌梗死后患者中，SCD事件的绝对数量要多得多，尽管该人群中SCD的发生率较低。最近的研究表明，TWA检测在该人群中也具有预测性。对TWA进行绝对量化而非简单分为“正常”或“异常”，对于更精确地分层心律失常风险的程度似乎很有价值。在某些人群中可能需要进行纵向检测，尽管最佳间隔仍有待确定。将TWA与自主神经功能的非侵入性标志物（如心率震荡）相结合，可能会进一步提高预测准确性。未来的发展可能会扩大TWA检测在常规运动和动态心电图监测中的作用，以筛查低风险人群并指导药物治疗和基于器械的治疗。
