Ventricular Gradient as a Risk Factor in Survivors of Acute Myocardial Infarction VELISLAV BATCHVAROV, KATERINA HNATKOVA, AZAD GHURAN, JAN POLONIECKI, A. JOHN CAMM, and MAREK MALIK From the Department of Cardiological Sciences, St. George’s Hospital Medical School, London, England BATCHVAROV, V., ET AL.: Ventricular Gradient as a Risk Factor in Survivors of Acute Myocardial Infarction. The total cosine between R and T (TCRT) (angular difference between the spatial QRS and T wave loops) is a technical elaboration of the concept of ventricular gradient (VG), whose power as a risk stratifier in post-MI patients has already been demonstrated. Recently, it was reported that TCRT differed significantly between healthy men and women, which suggested that its predictive power might be gen- der dependent. The aim of the study was to investigate TCRT and its association with cardiac mortality in male and female survivors of acute MI. TCRT was measured from digital Frank orthogonal XYZ-lead ECGs recorded before hospital discharge in 681 survivors of acute MI (82% men, age: men 57.0 ± 8.4 years, women 59.6 ± 8.1 years, P = 0.002). During a follow-up censored at 5 years, cardiac mortality rates were 9.7% and 12.1% in men and women, respectively (P = 0.42). There were no significant difference in TCRT between men and women (-0.150 ± 0.704 vs -0.070 ± 0.731, P = 0.26). In univariate Cox regression analysis, TCRT < -0.88 was related to a 5-year cardiac mortality in men (relative risk [RR] 3.67, 95% confidence interval [CI] 2.13–6.34, P = 1.9 × 10 -6 ), and women (RR 5.16, 95% CI 1.83–14.56, P = 0.0015). Depressed TCRT was strongly associated with increased long-term cardiac mortality in survivors of acute MI. Its predictive power did not differ significantly between the sexes. The role of TCRT as a risk-stratifier in post-MI patients deserves further prospective assessment in multivariate models with established risk factors. (PACE 2003; 26[Pt. II]:373–376) ventricular gradient, repolarization, gender differences, risk stratification, myocardial infarction Introduction The conflict between the cost of health care and the prophylactic efficacy of implantable car- dioverter defibrillators (ICDs), 1,2 and the design of future antiarrhythmic drug trials enhance the need for accurate risk stratification of postmyocardial infarction (post-MI) patients. However, the predic- tive value of presently established risk stratifiers is modest even with the use of multiple variables. 3 Recently, a new electrocardiographic (ECG) descriptor of ventricular repolarization was intro- duced, which quantifies the vectorial deviation be- tween the QRS and T wave loops (total cosine between R and T, TCRT). 4 TCRT is based on and further develops the classical concept of ventric- ular gradient (VG). 5,6 One study indicated that TCRT was a strong and independent predictor of adverse outcome in post-MI patients. 7 However, a recently by published extensive analysis of continuous 24-hour, 12-lead digital ECGs demonstrated that TCRT differed signifi- cantly between healthy young men and women, 8 Supported in part by The Wellcome Trust, London, England and the British Heart Foundation, London, England. Address for reprints: Velislav Batchvarov, M.D., Dept. of Cardi- ological Sciences, St. George’s Hospital Medical School, Cran- mer Terrace, London SW17 0RE, England. Fax: +44-20-8725- 0846; e-mail: vbatchva@sghms.ac.uk which suggested that its value as a risk stratifier may be dependent on the patient’s sex. This study analyzed a prospectively collected database of survivors of acute MI with a relatively long follow-up to compare TCRT and its associa- tion with long-term cardiac mortality in male and female patients. Methods The study used the database of the St. George’s Post-Infarction Research Survey which screened 1,338 patients (≥75 years of age) who were ad- mitted to St. George’s Hospital for acute MI be- tween 1984 and 1994. 9 Patients with valvular heart disease, permanent pacemakers, atrial fibrillation, and a QRS complex >120 ms were excluded by the protocol of the survey. Before hospital discharge, a signal-averaged ECG (SAECG) was recorded in 681 patients in Frank orthogonal bipolar XYZ leads us- ing an ART 1200 EPX device with a 40–250 Hz filter (Arrhythmia Research Technology, Austin, TX, USA). The study population consisted of 557 men (mean age 57.0 ± 8.4 years) and 124 women (mean age 59.6 ± 8.1 years, P = 0.002). TCRT was calculated as a cosine of the angle between the spatial QRS and T wave loops reconstructed in a minimum dimensional space from the digi- tally recorded XYZ leads of the SAECG recordings. Details of the physiological background and the PACE, Vol. 26 January 2003, Part II 373