Objectives: To explore the relation between non invasive measures of cardiac function and sudden cardiac death, as well as the development and utility of an index integrating these variables to identify patients at increased risk of this mode of death. Design: UK HEART(United Kingdom heart failure evaluation and a ssessment of risk trial) was a prospective study conducted between December 1993 and April 2000. The study was specifically designed to identify non invasive m arkers of death and mode of death among patients with chronic heart failure. Set ting: 8 UK general hospitals. Main outcome measures: Death and mode of death. Re sults: 553 patients aged a mean (SD) of 63(10) years, in New York Heart Associat ion functional class 2.3(0.02), recruited prospectively. After 2365 patient yea rsfollow up, 201 patients had died (67 suddenly). Predictors of sudden death w ere greater cardiothoracic ratio, QRS dispersion, QT dispersion corrected for ra te(QTc) across leads V1 V6 on the 12 lead ECG, and the presence of nonsustained ventricular tachycardia. The hazard ratio and 95%confidence intervals (CI) of sudden death for a 10%increase in cardiothoracic ratio was 1.43 (95%CI 1.20 to 1.71), for a 10%increase in QRS dispersion 1.11 (95%CI 1.04 to 1.19), for the presence of non sustained ventricular tachycardia 2.03(95%CI 1.27 to 3.25), a nd for a 10%increase in QTc dispersion across leads V1-V6 1.03 (95%CI 1.00 to 1.07) (all p< 0.04). An index derived from these four factors performed well in identifying patients specifically at increased risk of sudden death. Conclusion s: Results show that an index derived from three widely available non invasive investigations has the potential to identify ambulant patients with chronic hear t failure at increased risk of sudden death. This predictive tool could be used to target more sophisticated investigations or interventions aimed at preventing sudden death. Objectives: To explore the relation between non invasive measures of cardiac function and sudden cardiac death, as well as the development and utility of an index integrate these variables to identify patients at increased risk of this mode of death. Design: UK HEART (United Kingdom heart failure evaluation and a ssessment of risk trial) was a prospective study conducted between December 1993 and April 2000. The study was specifically designed to identify non invasive m arkers of death and mode of death among patients with chronic heart failure. Set ting: 8 Re sults: 553 patients aged a mean (SD) of 63 (10) years, in New York Heart Associat ion functional class 2.3 (0.02), recruited prospectively. After 2365 Predictors of sudden death w ere greater cardiothoracic ratio, QRS dispersion, QT dispersion corrected for ra te (QTc) across leads V1 V6 on the 12 l The hazard ratio and 95% confidence intervals (CI) of sudden death for a 10% increase in cardiothoracic ratio was 1.43 (95% CI 1.20 to 1.71) for a 10% increase in QRS dispersion 1.11 (95% CI 1.04 to 1.19) for the presence of non sustained sustained ventricular tachycardia 2.03 (95% CI 1.27 to 3.25), a nd for a 10% increase in QTc dispersion across leads V1- V6 1.03 (95% CI 1.04 to 1.19) 1.00 to 1.07) (all p <0.04). An index derived from these four factors performed well in identifying patients specifically at increased risk of sudden death. Conclusion s: Results show that an index derived from three widely available non-invasive investigations has the potential to identify ambulant patients with chronic hear t failure at increased risk of sudden death. This predictive tool could be used to target more sophisticated investigations or interventions aimed at preventing sudden death.