Cardiac autonomic dysfunction in elderly women with myocardial infarction.

AIMS: Elderly women with myocardial infarction (MI) show poorer outcomes than men. In patients with MI, reduced heart rate variability (HRV) is associated with an increased risk of mortality. Thus, we aimed to investigate HRV in elderly women with MI. METHODS: HRV indexes in women 50 years of age or older were compared to those in age-adjusted men with MI: geometric (triangular index), linear (low frequency [LF, ms(2)], high frequency [HF, ms(2)], standard deviation (SD) of normal R-R wave intervals [SDNN], square root of the mean of the sum of the squares of differences between adjacent normal R wave intervals [RMSSD]) and nonlinear Poincaré analysis [SD1 and SD2, ms]. RESULTS: Women had higher MI recurrence than men (11% vs. 5% with two MIs; 6% vs. 1% with three MIs). Overall HRV, the triangular index and SDNN were considerably lower in women than men (3.1 [2.5-4.4] vs. 4.5 [3.2-5.9] and 9.3 [6.9-15.8] vs. 19.2 [11.4-26.4] respectively; p < 0.001). Moreover, HRV indexes (HF, LF/HF, RMSSD, and SD1) were significantly lower in women (62.2%, 55.6%, 37.1%, and 37.2% respectively; p < 0.01). CONCLUSION: This study suggests that elderly women with MI may have a worse prognosis than men, indicated by cardiac autonomic dysfunction. Since our study is cross-sectional and cannot infer causality, causation should be confirmed in further longitudinal studies.

Heart rate detrended fluctuation indexes as estimate of obstructive sleep apnea severity.

In the present study, we aimed at investigating a heart rate variability (HRV) biomarker that could be associated with the severity of the apnea-hypopnea index (AHI), which could be used for an early diagnosis of obstructive sleep apnea (OSA). This was a cross-sectional observational study on 47 patients (age 36 ±â€Š9.2 standard deviation) diagnosed with mild (23.4%), moderate (34%), or severe (42.6%) OSA. HRV was studied by linear measures of fast Fourier transform, nonlinear Poincaré analysis, and detrended fluctuation analysis (DFA)­DFA α1 characterizes short-term fluctuations, DFA α2 characterizes long-term fluctuations. Associations between polysomnography indexes (AHI, arousal index [AI], and oxygen desaturation index [ODI]) and HRV indexes were studied. Patients with different grades of AHI had similar sympathovagal balance levels as indicated by the frequency-domain and Poincaré HRV indexes. The DFA α2 index was significantly positive correlated with AHI, AI, and ODI (Pearson r: 0.55, 0.59, and 0.59, respectively, with P < 0.0001). The ROC analysis revealed that DFA α2 index predicted moderate and severe OSA with a sensitivity/specificity/area under the curve of 0.86/0.64/0.8 (P = 0.005) and 0.6/0.89/0.76 (P = 0.003), respectively. Our data indicate that the DFA α2 index may be used as a reliable index for the detection of OSA severity.