Alteración de la variabilidad del ritmo cardíaco en pacientes con síndrome coronario agudo sin supradesnivel del segmento ST: Experiencia preliminar

background: heart rhythm variability (hrv) is an indicator of autonomous nervous system modulation, which may be analyzed in both time and rate domains. a decrease in hrv following st segment elevation acute myocardial infarction has been shown to be associated to increased cardiovascular mortality and ventricular arrhythmias. aim: to evaluate whether a decreased hrv is correlated to myocardial damage markers (ck mb mass and troponin t) in patients with a non-st segment elevation acute coronary syndrome (nste-acs) methods: patients with nste-acs in sinus rhythm within 24 hours of admission were included. we excluded patients with prior mi, heart failure class iii or iv, arrhythmias or severe co-morbidity. clinical characteristics, ck mb mass and serum troponin levels were determined. hrv was measured in a 5 min recording using the polar s810 monitor with the patient lying flat. the software hrv analysis 1.1 was used to process hrv data. results: 14 patients were studied. in comparison with normal reference values, hrv in the time domain was significantly decreased (rr 902 ± 23.4 ms; rmssd 23.38 ms; pnn50 6%). patients with positive myocardial damage markers exhibited altered hrv parameters in the frequency domain (high frequency: hf 22.7 ms2 p:0.008, low frequency: lf 66.9 u.n. p:0.016). patients with high ck mb mass and elevated troponin levels had significantly lower high frequency values and significantly increased means for low frequency variables, compared to patients with normal ck mb mass and troponin levels. these findings reflect an increased sympathetic drive on hrv along with a decreased para-sympathetic regulation in these patients. conclusion: changes in 5 min recordings of hrv suggest a decreased activity of the para sympathetic system in patients with nste-acs.