BackgroundDecreased heart rate variability (HRV) is related to higher morbidity and mortality. In this study we evaluated the linear and nonlinear indices of the HRV in stable angina patients submitted to coronary angiography.MethodsWe studied 77 unselected patients for elective coronary angiography, which were divided into two groups: coronary artery disease (CAD) and non-CAD groups. For analysis of HRV indices, HRV was recorded beat by beat with the volunteers in the supine position for 40 minutes. We analyzed the linear indices in the time (SDNN [standard deviation of normal to normal], NN50 [total number of adjacent RR intervals with a difference of duration greater than 50ms] and RMSSD [root-mean square of differences]) and frequency domains ultra-low frequency (ULF) ≤ 0,003 Hz, very low frequency (VLF) 0,003 – 0,04 Hz, low frequency (LF) (0.04–0.15 Hz), and high frequency (HF) (0.15–0.40 Hz) as well as the ratio between LF and HF components (LF/HF). In relation to the nonlinear indices we evaluated SD1, SD2, SD1/SD2, approximate entropy (−ApEn), α1, α2, Lyapunov Exponent, Hurst Exponent, autocorrelation and dimension correlation. The definition of the cutoff point of the variables for predictive tests was obtained by the Receiver Operating Characteristic curve (ROC). The area under the ROC curve was calculated by the extended trapezoidal rule, assuming as relevant areas under the curve ≥ 0.650.ResultsCoronary arterial disease patients presented reduced values of SDNN, RMSSD, NN50, HF, SD1, SD2 and -ApEn. HF ≤ 66 ms2, RMSSD ≤ 23.9 ms, ApEn ≤−0.296 and NN50 ≤ 16 presented the best discriminatory power for the presence of significant coronary obstruction.ConclusionWe suggest the use of Heart Rate Variability Analysis in linear and nonlinear domains, for prognostic purposes in patients with stable angina pectoris, in view of their overall impairment.

ObjectiveTo evaluate a possible evolutionary post-heart transplant return of autonomic function using quantitative and qualitative information from recurrence plots.MethodsUsing electrocardiography, 102 RR tachograms of 45 patients (64.4% male) who underwent heart transplantation and that were available in the database were analyzed at different follow-up periods. The RR tachograms were collected from patients in the supine position for about 20 minutes. A time series with 1000 RR intervals was analyzed, a recurrence plot was created, and the following quantitative variables were evaluated: percentage of determinism, percentage of recurrence, average diagonal length, Shannon entropy, and sample entropy, as well as the visual qualitative aspect.ResultsQuantitative and qualitative signs of heart rate variability recovery were observed after transplantation.ConclusionThere is evidence that autonomic innervation of the heart begins to happen gradually after transplantation. Quantitative and qualitative analyses of recurrence can be useful tools for monitoring cardiac transplant patients and detecting the gradual return of heart rate variability.

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ObjectiveTo evaluate the impact of chronic kidney disease on the survival of patients – 80 years of age undergoing percutaneous coronary intervention (PCI) in the long term.Methods273 subjects who underwent PCI between January 2010 and January 2016 were divided into four categories: (1) stable angina (SA) and creatinine clearance – 30 (n = 24); (2) patients with SA and CrCl <30 (n = 70); (3) patients with acute coronary syndrome (ACS) and CrCl – 30 (n = 51); (4) patients with ACS and ICC <30 (n = 128). Mortality curves were evaluated using the Kaplan-Meier method and differences between groups were compared by log-rank statistic. Multivariate analysis was performed using the Cox proportional hazards method. The 4 groups were compared and the survival between the groups was evaluated.ResultsOctogenarian patients with CrCl <30 with SA and ACS have lower long-term survival (p < 0.0001).ConclusionCKD has a worse long-term prognosis for patients undergoing PCI.