RiskStratification withLow-level Exercise Testing 2WeeksAfter AcuteMyocardial Infarction

SUMMARY Weenrolled 250patients with acute myocardial infarction after they hadbeendischarged from thecardiac intensive careunit. Among236patients whoperformed alow-level exercise test just before hospital discharge, 52(22%) hadexercise-induced STdepression ofatleast 0.1mVinECGleadV,,102(43%) hadventricular arrhythmias, and121(51%) hadanexercise capacity ofshorter than6minutes. We usedmultiple logistic regressionanalysis toinvestigate theassociation ofexercisevariables with1-year cardiac mortality. Exercise duration andventricular premature depolarizations (VPDs) weresignificantly associated with1-year mortality after acutemyocardial infarction, bothwithandwithout control oftheinfluence ofother exercise variables statistically; theassociation ofexercise-induced STdepression withl-year cardiac mortality wasnot statistically significant. Standardized regression coefficients showedthatthevariables ranked inthefollowing order intermsofpredictive value: exerciseduration, VPD frequency andSTdepression. Jackknife techniques showed that multiple logistic regression usingthethree exercise variables washighly accurate inpredicting 1yearmortality. EXERCISETESTINGinpatients withclinically suspected orovert chronic ischemic heart disease can define safelimits ofexercise, define theexertional threshold ofangina pectoris orST-segment abnormalities, anddisclose unanticipated arrhythmias or left ventricular failure.'-" Exercise testing also maybe useful inpatients whohaveanunwarranted diagnosis ofheart disease byshowing that they arefree ofcardiacsigns andsymptoms during maximumexercise testing. Exercise testing canalso identify risk forcardiacdeath ornonfatal reinfarction inpatients with chronic ischemic heartdisease'-": Exertional STsegmentdisplacement, anginaduring exercise, exercise-related arrhythmias, exertional hypotension, exercise duration, maximumexercise systolic blood pressure, maximumexercise heart rate, andexerciseinduced left ventricular failure allhavebeenfound to identify subgroups athighoratlowrisk forsubsequent cardiac death.'-" Exercise testing isnotwidely usedclinically to evaluate patients whoareconvalescing fromacute myocardial infarction (AMI). We designed thepresentstudy todetermine ifalow-level exercise test performed just before hospital discharge forpatients convalescing fromAMIwould beofprognostic value. We performed astandardized low-level exercise test in236