Aerobic Training in Post-MI Patients With DPN

Overview

Cardiac rehabilitation (CR) is categorized by the American College of Cardiology "class IA recommendation" in the management of patients with cardiovascular disease (CVD) including post-myocardial infarction (MI) patients, who have reduced functional capacity and impaired quality of life. Studies have reported that post-MI patients enrolled in exercise-based CR (EB-CR) show improved functional capacity, significant decrease risk of re-infarction, and 25% reduction in mortality. Aim: To define the effect of diabetic peripheral neuropathy (DPN) on the outcome measures of exercise based-cardiac rehabilitation (EB-CR) program in post-myocardial infarction (MI) patients with type-II diabetes mellitus (DM). Methods: Thirty-seven post-MI patients with type-II DM were enrolled in the study within 1-6 months of MI from those referred for cardiac rehabilitation in the cardiac rehabilitation unit, Alexandria Teaching Hospital. Seven patients were lost. Fifteen patients attended 8 weeks of aerobic training program (exercise group; 12 men and 3 women) while 15 patients did not (control group; 11 men and 4 women). The exercise group was assessed for the presence of peripheral neuropathy and patients were accordingly subdivided into those with DPN "group A" and those without "group B". All groups were evaluated at baseline and at the end of the study. Evaluation included Duke Activity Status Index (DASI) questionnaire, 6-minute walk test, and symptom-limited treadmill exercise stress test (EST). Outcome measures included: DASI score; 6-minute walk test distance (6MWD); and heart rate (HR), blood pressure (BP), rate pressure product (RPP), and functional capacity in metabolic equivalents (METs) measured during EST.

The study population included post-MI patients with type-II DM within 1 to 6 months from onset of MI from those referred for cardiac rehabilitation in the cardiac rehabilitation unit, Alexandria Teaching Hospital. Patients were diagnosed as having MI according to the Joint ESC/ACCF/AHA/WHF Task Force for the Universal Definition of MI and DM according to the 2016 American Diabetes Association guidelines. All patients were assessed by a cardiologist by clinical examination, electrocardiogram and echocardiography. Patients were excluded if they had any contraindication to exercise stress test (EST) or CR,systemic illness other than DM or hypertension, neurological disorders other than DPN, or had loss of protective sensation (anesthesia) and/or ulcerations in the lower limbs. All patients were informed about the nature of the study and an informed consent was obtained from all of them. The protocol was approved by the ethics committee. Patients were divided into 2 groups; those enrolled in EB-CR program "exercise group" and those not enrolled in EB-CR program "control group". Baseline evaluation for both groups included: demographic data collection, history taking, clinical examination, electrophysiological studies to confirm the presence or absence of neuropathy (sural sensory, posterior tibial and deep peroneal motor conduction studies), total neuropathy score to assess the clinical severity of DPN, Duke Activity Status Index questionnaire (DASI) to assess patients' physical activity level, Six-Minute Walk Test, and symptom-limited treadmill EST using Bruce protocol. All patients were on their regular medications including B-blockers during the EST. The exercise group underwent an outpatient EB-CR program (phase II) according to the American College of Sports Medicine guidelines for exercise prescription for cardiac patients.Sessions were 3 days/week for 8 weeks. The program included: Warm up (10 minutes): stretching exercises. Aerobic exercise training using treadmill (30 - 60 minutes/session): with target heart rate (HR) at 45 - 75% of HR reserve. The maximal HR (HR max) was derived from that obtained during EST. Patients who had ischemic/arrhythmic manifestations during EST, exercise intensity was prescribed at a HR below the ischemic threshold (10 beats below). Cool down (10 minutes): light intensity treadmill walking. Supervision was provided according to the risk status of each patient that was determined according to the American Association of cardiovascular and Pulmonary Rehabilitation criteria for risk stratification. Controls were advised to maintain their medications and regular activities of daily living. The follow-up evaluation included: DASI, Six Minute Walk Test and symptom limited EST. The Outcome measures were DASI score, Six-minute walk test distance (6MWD), functional capacity in metabolic equivalents (METs), HR, blood pressure (BP) and rate pressure product (RPP) at a given workload.