Prognostic value of Doppler-derived myocardial performance index in patients with left ventricular systolic dysfunction

Abstract

S studies have attempted to identify the prognostic factors of patients with heart failure and left ventricular (LV) systolic dysfunction.1–4 In this population, echocardiographic parameters have been described to predict a poor outcome including LV enlargement, low LV ejection fraction or fractional shortening, high mitral flow E/A ratio, and short deceleration time of mitral E flow.1–4 Early reports have shown that isovolumic intervals can be used to analyze cardiac dysfunction in patients with heart failure.5–11 Recently, a Doppler-derived interval index including systolic and diastolic performance of the left ventricle was reported to be a useful, sensitive, and reproducible parameter to detect myocardial dysfunction in many clinical situations.12–14 This index, which is easy to obtain, was defined as the ratio of the summation of isovolumic contraction and relaxation time to ejection time. However, the prognostic value of this index in patients with heart failure and LV systolic dysfunction remains unclear and has not been previously prospectively studied. Therefore, we decided to record, in a prospective study, this index in patients with LV systolic dysfunction to analyze its prognostic value. • • • Between February 1996 and February 1998, we prospectively included 100 consecutive patients (79 men and 21 women, aged 65 11 years) in sinus rhythm, hospitalized with clinical congestive heart failure and LV ejection fraction 40% at echocardiographic examination, and without any valvular heart disease. Patients were clinically stable for at least 3 weeks. All echocardiographic measurements were analyzed without knowledge of clinical data. The entire echocardiography and Doppler examination was completed for each patient (Sonos 2000 or 5500, Philips Ultrasound System, probe 2.5 MHz, Andover, Massachusetts) including measurements of LV diastolic and systolic diameters, diastolic and systolic volumes using Simpson’s method,15 and right ventricular end-diastolic diameter. LV ejection fraction and shortening fraction were calculated. On mitral flow, we measured maximum velocity of E and A waves and the deceleration time of the E wave, and we calculated E/A ratio. The myocardial performance index (MPI) was calculated as previously described by Tei et al.14 Briefly, using pulsed Doppler, we recorded mitral and aortic flow from 4 and 5 apical chamber views, with a 1-mm sample placed at the level of mitral tips during diastole and at the level of the aortic annulus during systole. Ejection time b was measured from the opening to the closure of the aortic valve on the LV outflow velocity profile. The interval a was obtained from mitral flow recordings from the cessation to the onset of mitral inflow, which was equal to the sum of isovolumic relaxation and contraction time and ejection time. Thus, a b represented the sum of isovolumic relaxation and contraction time. Therefore, the MPI was calculated as: MPI (a b)/b . Tricuspid regurgitation was recorded and pulmonary systolic artery pressure was calculated. All reported parameters are the average of 5 measurements. Follow-up information was obtained from the family physician or by direct-mail questionnaires or interviews. Results are presented as mean SD. A 2-sample t test was performed to compare continuous variables. The chi-square test was used to compare categorical variables. A p value 0.05 was considered statistically significant. The Kaplan-Meier method was used for cumulative survival analysis, with the log-rank test for assessing statistical differences between curves. Univariate analysis was applied to define differences between survivors and deaths. Multivariate Cox proportional-hazards regression (toward stepwise procedure) was used to investigate whether the variables identified with a p value 0.10 in the univariate analysis were independent predictors of mortality. The previously mentioned variables were treated as dichotomous variables. Analysis was done with STATVIEW computer version 5 software (Abacus Concepts, Inc., Berkeley, California). • • • Most patients were men (79%), in New York Heart Association (NYHA) functional class III to IV (77%). Etiology of heart failure was coronary artery disease in 65% and idiopathic-dilated cardiomyopathy in 35%. The baseline clinical and echocardiographic characteristics of patients are listed in Table 1. Mean LV ejection fraction was 33 6% and mean MPI was 0.69 0.30 (range 0.10 to 1.70). There was a significant correlation between the index and the ejection fraction (r 0.35, p 0.0043), the shortening fraction (r 0.34, p 0.006), LV end-diastolic (r 0.40, p 0.0008) and end-systolic (r 0.42, p 0.0005) diameters, and LV end-diastolic (r 0.31, p 0.013) From the Department of Cardiology and the UPRES Unit, South Hospital, University of Picardie, Amiens, France; and the Division of Cardiovascular and Internal Medicine, Mayo Clinic, Rochester, Minnesota. Dr. Slama’s address is: Unite de reanimation, Service de Nephrologie, Hopital Sud, 80054 Amiens Cedex 1, France. E-mail: MSlama0508@aol.com. Manuscript received May 14, 2002; revised manuscript received and accepted July 29, 2002.