engleski

Lack of prognostic value of decreased heart variability following coronary artery bypass grafting.

Background: Decreased heart rate variability (HRV) may predict cardiac death after myocardial infarction (MI). Coronary artery bypass grafting (CABG) strongly decreases HRV, but improves survival. The aim of the study was to determine the prognostic value of HRV decreased by coronary surgery. Design and Methods: Four-year follow-up was performed in 175 consecutive patients with HRV decreased by CABG (51) or MI (124). Mortality and secondary events rate were analysed. Decreased HRV, defined by the standard deviation of mean RR interval (SDNN) lower then 100 ms, was detected by a routine 24-hour Holter ECG made 3 weeks to 3 months after MI or CABG. Two groups did not differ except by age ; CABG patients were younger (56 vs 64 years, p<0.01), but this did not influence differences in survival (&#61539; 2=0.24 ; NS). Results: HRV was lower in CABG patients than among MI patients (SDNN = 66&#61617; 20 ms vs 77&#61617; 14 ms ; p<0.001), but cumulative survival and event-free survival were much better in the CABG group than in the MI group. During a 46&#61617; 20 months follow-up, there were 10% new events in CABG group and 43% in MI group (p<0.001). Mortality was 8% in CABG group and 33% in MI group (p<0.001). Unlike in the MI group, HRV was not different between survivors and non- survivors in the CABG group. Conclusion: In contrast to the strong prognostic potential of HRV in patients with MI, decreased HRV has no prognostic significance in patients who have undergone CABG surgery.

heart rate variability; prognosis; cardiac surgery

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