Treadmill Testing Two Weeks After MyocardiaJ Infarction: Comparison With Late Retesting

Abstract

Introduction:

Recently experimental studies have been published wherein treadmill exercise testing prior to discharge after acute myocardial infarct ion has been performed in order to obtain guidelines for individual rehabilitation, exercise prescription and identification of high risk patients (2, 3, 5, 7). The objectives were, firstly to establish the safety and work capacity of these patients,, secondly to provide data for comparison with testing later after a longer conventional period, and, lastly to provide data for luture identification, of prognostic indexes.

Materials and Methods:

Subjects.• These were consecutive male patients with new acute transmural infarction according to WHO criteria admitted to the NICVD (Pakistan). These patients had been allowed to use the bathroom from day 2 and were fully ambulated from day 5 onwards. None of these subjects had in the period between the initial and later treadmill test been enrolled in any exercise programme and were instructed to resume normal activities as prior to their infarction. ETT 2 was performed a mean interval of 7.2±2.3 months after the acute infarction.

Results:

(Table I):
Clinical Characteristics.
All patients were males. Mean age of patients at time of infarction was 51 years (SD ± 7 years). 26 patients (65%) had an anterior myocardial infarction and 14 patients (35%) had an inferior myocardial infarction. At the time of ETT I no patient was on digoxin, diuretics or beta blockers. At the time of ETT 2 only one patient was on digoxin, 4 patients were on diuretics and 5 patients were on beta—blockers. No patient had suffered a recurrent myocardial infarction nor had been hospitalized.

Symptoms during exercise:
During ETT1 exercise was terminated due to fatigue and/or dyspnea in 28 patients and clue to Angina in 12 patients. During ETT2 exercise was discontinued due to fatigue or dyspnea in 29 patients and due to anginu in 11 patients. No patient experienced prolonged chest pain and all anginal episodes subsided spontaneously or immediately after sublingual nitroglycerine. No patient experienced any new symptoms in the first 24 hours after the exercise tests and a set of tissue enzymes done 24 hours after exercise were normal in all patients.

Discussion:

The utility of graded exercise testing several weeks or months after acute myocardial infarction has been established(8). Attempts are being made to establish the safety and utility of single exercise testing soon after uncomplicated acute myocardial infarction(1). As the study is ongoing, only a later analysis will reveal the true long term prognosis of these patients and identify parameters recorded during ETT1 and ETT2 wich may serve as useful, predictors of prognosis. Since ETT1 can be performed safely in selected patients and because besides many other claimed advantages it provides information similar to ETT2, early treadmill testing may in such patients replace the conventional exercise test done several weeks or months after acute infarction.