Effects of blood pressure, blood cholesterol and smoking on the functional capacity of post myocardial infarction patients in the early stages of cardiac rehabilitation

Abstract

The purpose of the study was to examine the contribution of blood pressure, blood cholesterol and smoking on the functional capacity of post myocardial infarction patients (PMIP) during exercise. Forty six male non-blockade recent PMIP were measured for systolic blood pressure (SBP) and blood cholesterol (BC), and were also asked about personal smoking status. The subjects all performed a graded exercise test (modified Bruce protocol) on a motorized treadmill, during which time ratings of perceived exertion and blood pressure were measured every 3 min, oxygen uptake (VO₂) and heart rate (HR) were measured every 30s and a 12-lead electrocardiogram was recorded continuously. Metabolic equivalents (METs) were derived from VO₂and the patients’ risk factors for coronary heart disease were obtained using the coronary risk-disc and expressed as Dundee Rank (DR). The results produced a multiple regression of SBP, BC and smoking with exercise time of r = 0.76 and with METs of r = 0.73 which were very similar to the values using DR alone. A DR value of 71 and above was equivalent to a MET value of 7.5 which is often used as the criterion for considering a patient to be at ‘low risk’ during cardiac rehabilitation. This means that the Dundee Risk-Disc may have a place in assisting the health professional to establish which patients should be capable of achieving the 7.5 MET threshold. This could be useful in giving special attention to those patients who are underperforming. The poor correlation between RPE and VO₂recognises individual differences and demonstrates the need for each patient to establish their own RPE/work relationship.