Use of stress echocardiography to predict death in diabetic patients

Abstract

Background. Coronary artery disease is a major cause of mortalify in pts with diabetes mellitus (DM). However, symptom evaluation may be limited because of silent ischemia, and the use of standard exercise (Ex) testing in DM may be difficult because of vascular disease, neuropathy or visual problems. We sought whether stress echo using exercise (ExE, when feasible) or dobutamine echo (DbE) could be used to identify DM pts at risk. Methods. We studied 937 DM pts (age 59±13 y, 529 men); only 186 (20%) had chest pain, the majority of tests being performed for prognostic evaluation - 276 (30%) had prior myocardial infarction and 103 had past revasculadzation. ExE was performed in 333 pts able to exercise maximally (8.2±3.2 METS). DbE using a standard dobutamine stress was used in 604 pts. Pts were followed for up to 9 years (av 3.9±2.3), for death and revascularization. Results.Normal studies were obtained in 567 (60%); 29% had resting LV dysfunction and 25% had ischemia. Abnormalities were confined to one territory in 183 pts (20%), and to multiple territories in 187 pts (20%). Death (in 275 pts, 29%) was predicted by referral for pharmacologic stress (hazard ratio 3.89, p<0.000t), number of ischemic terdtodes (HR 1.42, p<0.0001 ), age (HR 1.02, p--0.001 ), and heart failure (HR 1.51, p=0.01). In stepwise models replicating the sequence of clinical evaluation, the predictive power of independent clinical predictors (age and heart failure, model chisq 39.6) was significantly enhanced by addition of LV dysfunction data (model chisq 60.9) and further enhanced by ischemia (model chisq 79.4). However, pts with a normal DbE had a higher event-rate (6% per yr) than those with normal ExE (1.2% per yr). Conclusions. Results of stress echo are independent predictors of death in DM pts with known or suspected CAD. Ischemia adds dsk that is incremental to clinical risks and LV dysfunction. Inability to exercise is a powerful negative feature and a negative DbE does not necessarily signify low dsk in this group.