Critical Value of Baroreflex Sensitivity Determined by Spectral Analysis in Risk Stratification After Myocardial Infarction

Abstract

The risk of cardiac death in patients after MI is predicted by a decreased baroreflex sensitivity (BRS). The critical value of BRS based on phenylephrine administration is 3 ms/mmHg. The aim of this study was to determine the critical value of BRS assessed by spectral analysis of spontaneous fluctuations in pulse intervals and blood pressure. Digital blood pressure was recorded noninvasively (3 min, controlled breathing 0.33 Hz) in 112 patients, 8–18 days after MI. Nine patients died during the first year after MI. BRS was determined as the gain between the spectrum of the variability of systolic blood pressure and the cross‐spectrum between the variability of pulse intervals and systolic blood pressure. The gain at the frequency of 0.1 Hz was taken as the measure of BRS. Sensitivity, specificity, and the positive predictive value were calculated in the range of 1–10 ms/mmHg in steps of 1 ms/mmHg. The value of BRS above which sensitivity no longer increases and specificity decreases was taken as the optimal value. The critical value of BRS determined by spectral analysis was 3 ms/mmHg (sensitivity 77%; specificity 71 %). In conclusion, the spectral critical value of BRS determined by spectral analysis of spontaneous fluctuations in pulse intervals and blood pressure corresponds to the value determined by the phenylephrine method.

Development of Causal Interactions Between Systolic Blood Pressure and Inter-Beat Intervals in Adolescents

“…In this study, IBI intervals were assessed from the finger blood pressure signal. We have used the IBI signal for BRS determination since 1992 (Honzikova et al 1992) with comparable results based on the measurement of R-R intervals from ECG (Persson et al 2001, Honzikova et al 2000b. However, R-R intervals are normally used.…”

Effects of breathing frequency on baroreflex effectiveness index and spontaneous baroreflex sensitivity derived by sequence analysis

“…High-frequency paced breathing (0.25 or 0.33 Hz) is required to avoid overestimation when measuring BRS LF [10,11]. This is because spontaneous breathing in humans is spread over a wide range of frequencies [12] and breathing in the 0.1 Hz range will cause a greater BRS LF value due to respiration-related nonbaroreflex-mediated R-R interval fluctuations in the low-frequency band [13].…”

“…Reduced BEI and BRSseq predict all-cause mortality and sudden death, respectively, in hypertensive patients with chronic renal failure [9]. Furthermore, a BRS LF less than 3 ms/mmHg is significantly associated with cardiac events in heart failure patients [10] and is able to predict cardiac death in patients after myocardial infarction [11].…”

Changes in baroreceptor sensitivity after eversion carotid endarterectomy

“…2-5 BRS lower than 3 ms/mm Hg is a powerful independent prognostic risk factor for sudden cardiac death. 32,33 An enhanced BRS had beneficial effects on the outcome of patients with cardiovascular disease, possibly by preventing ventricular arrhythmias. 34 Chao et al found that patients with carotid artery stenosis exhibited a significant reduction in BRS compared with controls.…”