Long-term lifestyle changes maintain the autonomic modulation induced by rehabilitation after myocardial infarction

The altered autonomic balance observed after myocardial infarction is shift ed toward a higher parasympathetic tone by rehabilitation. This effect pers ists after 1 year, however we observed a discrete variability in the long-t erm sympathovagal balance among patients. We postulated that such variabili ty derives from the disparate adherence of patients to lifestyle prescripti ons regarding exercise continuance and smoking avoidance. To test this hypo thesis, we reviewed the data of 40 patients, who completed with a favourabl e autonomic modulation the initial rehabilitation phase after myocardial in farction and underwent the annual follow-up. One year after infarction, 23 patients complied to the advice about regular exercise and smoking avoidanc e (adherent, Group 1); 17 did not (non-adherent, Group 2). Groups were simi lar for age, site of infarction, left ventricular function, stress test dur ation and therapy. The ratio LF/HF, derived from the power spectral density of RR intervals variability, was used as an index of the sympathovagal bal ance. It was obtained from 15 min of ECG at rest, assessed 1 month after MI (baseline), and repeated 3 months (rehabilitation) and 1 year (follow-up) afterwards. Rehabilitation increased parasympathetic tone in all patients, reducing LF/HF by 33%. At follow-up, this potentially favourable autonomic profile persisted only in Group 1 patients. In conclusion, after a first my ocardial infarction, the persistence of the potentially beneficial effect o f rehabilitation on the sympathovagal balance depends on the compliance to the lifestyle changes proposed during the initial phase. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.