Jean-Michel Gaspoz

Relation between heart rate variability and training load in middle-distance runners

PURPOSE Monitoring physical performance is of major importance in competitive sports. Indices commonly used, like resting heart rate, VO2max, and hormones, cannot be easily used because of difficulties in routine use, of variations too small to be reliable, or of technical challenges in acquiring the data. METHODS We chose to assess autonomic nervous system activity using heart rate variability in seven middle-distance runners, aged 24.6 +/- 4.8 yr, during their usual training cycle composed of 3 wk of heavy training periods, followed by a relative resting week. The electrocardiogram was recorded overnight twice a week and temporal and frequency indices of heart rate variability, using Fourier and Wavelet transforms, were calculated. Daily training loads and fatigue sensations were estimated with a questionnaire. Similar recordings were performed in a sedentary control group. RESULTS The results demonstrated a significant and progressive decrease in parasympathetic indices of up to -41% (P < 0.05) during the 3 wk of heavy training, followed by a significant increase during the relative resting week of up to +46% (P < 0.05). The indices of sympathetic activity followed the opposite trend, first up to +31% and then -24% (P < 0.05), respectively. The percentage increasing mean nocturnal heart rate variation remained below 12% (P < 0.05). There was no significant variation in the control group. CONCLUSION This study confirmed that heavy training shifted the cardiac autonomic balance toward a predominance of the sympathetic over the parasympathetic drive. When recorded during the night, heart rate variability appeared to be a better tool than resting heart rate to evaluate cumulated physical fatigue, as it magnified the induced changes in autonomic nervous system activity. These results could be of interest for optimizing individual training profiles.

Screening of Obstructive Sleep Apnea Syndrome by Heart Rate Variability Analysis

BACKGROUND Enhanced nocturnal heart rate variability (HRV) has been evoked in sleep-related breathing disorders. However, its capacity to detect obstructive sleep apnea syndrome (OSAS) has not been systematically determined. Thus, we evaluated the discriminant power of HRV parameters in a first group of patients (G1) and validated their discriminant capacity in a second group (G2). METHODS AND RESULTS In G1, 39 of 91 patients (42.8%) were identified as diseased by polysomnography, as were 24 of 52 patients (46%) in G2. Time-domain HRV variables (SD of NN intervals [SDNN], mean of the standard deviations of all NN intervals for all consecutive 5-minute segments of the recording [SDNN index], square root of the mean of the sum of the squares of differences between adjacent normal RR intervals [r-MSSD], and SD of the averages of NN intervals in all 5-minute segments of the recording [SDANN]) were calculated for daytime and nighttime periods, as well as the differences between daytime and nighttime values (Delta[D/N]). Correlations between HRV variables and OSAS status were analyzed in G1 by use of receiver-operating characteristic (ROC) curves and logistic regression analysis. By ROC curve analysis, 7 variables were significantly associated with OSAS. After adjustment for other variables through multiple logistic regression analysis, Delta[D/N]SDNN index and Delta[D/N] r-MSSD remained significant independent predictors of OSAS, with ORs of 8.22 (95% CI, 3.16 to 21.4) and 2.86 (95% CI, 1.21 to 6.75), respectively. The classification and regression tree methodology demonstrated a sensitivity reaching 89.7% (95% CI, 73.7 to 97.7) with Delta[D/N] SDNN index and a specificity of 98.1% (95% CI, 86.4 to 100) with Delta[D/N] SDNN using appropriate thresholds. These thresholds, applied to G2, yielded a sensitivity of 83% using Delta[D/N] SDNN index and a specificity of 96.5% using Delta[D/N] SDNN. CONCLUSIONS Time-domain HRV analysis may represent an accurate and inexpensive screening tool in clinically suspected OSAS patients and may help focus resources on those at the highest risk.

Gender differences in management and outcomes in patients with acute coronary syndromes: results on 20 290 patients from the AMIS Plus Registry

Background: Gender differences in management and outcomes have been reported in acute coronary syndrome (ACS). Objectives: To assess such gender differences in a Swiss national registry. Methods: 20 290 patients with ACS enrolled in the AMIS Plus Registry from January 1997 to March 2006 by 68 hospitals were included in a prospective observational study. Data on patients’ characteristics, diagnoses, procedures, complications and outcomes were recorded. Odds ratios (ORs) of in-hospital mortality were calculated using logistic regression models. Results: 5633 (28%) patients were female and 14 657 (72%) male. Female patients were older than men (mean (SD) age 70.9 (12.1) vs 63.4 (12.9) years; p<0.001), had more comorbidities and came to hospital later. They underwent percutaneous coronary intervention (PCI) less frequently (OR = 0.65; 95% CI 0.61 to 0.69) and their unadjusted in-hospital mortality was higher overall (10.7% vs 6.3%; p<0.001) and in those who underwent PCI (3.0% vs 4.2%; p = 0.018). Mortality differences between women and men disappeared after adjustments for other predictors (adjusted OR (aOR) for women vs men: 1.09; 95% CI 0.95 to 1.25), except in women aged 51–60 years (aOR = 1.78; 95% CI 1.04 to 3.04). However, even after adjustments, female gender remained significantly associated with a lower probability of undergoing PCI (OR = 0.70; 95% CI 0.64 to 0.76). Conclusions: The analysis showed gender differences in baseline characteristics and in the rate of PCI in patients admitted for ACS in Swiss hospitals between 1997 and 2006. Reasons for the significant underuse of PCI in women, and a slightly higher in-hospital mortality in the 51–60 year age group, need to be investigated further.

Cost-effectiveness of a new short-stay unit to “rule out” acute myocardial infarction in low risk patients☆

OBJECTIVES This study attempted to determine the safety and costs of a new short-stay unit for low risk patients who may be admitted to a hospital to rule out myocardial infarction or ischemia. BACKGROUND One strategy to reduce the costs of ruling out acute myocardial infarction in low risk patients is to develop alternatives to coronary care units. METHODS The short-term and 6-month clinical outcomes and costs for 592 patients admitted to a short-stay coronary observation unit at Brigham and Womens Hospital with a low (< or = 10%) probability of acute myocardial infarction were compared with those for 924 consecutive comparison patients who were eligible for the same unit but were admitted to other hospital settings or discharged home. Actual costs were calculated using detailed cost-accounting methods that incorporated nursing intensity weights. RESULTS The rate of major complications, recurrent myocardial infarction or cardiac death during 6 months after the initial presentation of the 592 patients admitted to the coronary observation unit was similar to that of the 924 comparison patients before and after adjustment for clinical factors influencing triage and initial diagnoses (adjusted relative risk 0.86, 95% confidence interval 0.49 to 1.53). Their median total costs (25th, 75th percentile) at 6 months (

Long-term decline in lung function, utilisation of care and quality of life in modified GOLD stage 1 COPD

1,927; 1,455, 3,650) were significantly lower than for comparison patients admitted to the wards

Even a low-dose of moderate-to-vigorous physical activity reduces mortality by 22% in adults aged ≥60 years: a systematic review and meta-analysis

4,712; 1,868, 11,187), to stepdown or intermediate care units (

Automatic Cardiac Event Recorders Reveal Paroxysmal Atrial Fibrillation after Unexplained Strokes or Transient Ischemic Attacks

4,031; 2,069, 9,169) or to the coronary care unit (

Relationship Among the Severity of Sleep Apnea Syndrome, Cardiac Arrhythmias, and Autonomic Imbalance

9,201; 3,171, 20,011) but were higher than for comparison patients discharged home from the emergency department (

Impact of a public campaign on pre-hospital delay in patients reporting chest pain.

403; 403,927) before and after the same adjustments (all adjusted p < 0.0001). CONCLUSIONS These data suggest that the coronary observation unit may be a safe and cost-saving alternative to current triage strategies for patients with a low risk of acute myocardial infarction admitted from the emergency department. Its replication in other hospitals should be tested.

Outcome of patients who were admitted to a new short-stay unit to “rule-out” myocardial infarction☆

Background: Little is known about the long-term outcomes of individuals with mild chronic obstructive pulmonary disease (COPD) as defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD). Methods: A population cohort of 6671 randomly selected adults without asthma was stratified into categories of modified GOLD-defined COPD (prebronchodilator spirometry). Further stratification was based on the presence or absence of respiratory symptoms. After 11 years, associations between baseline categories of COPD and decline in forced expiratory volume in 1 s (FEV1), respiratory care utilisation and quality of life as measured by the SF-36 questionnaire were examined after controlling for age, sex, smoking and educational status. Results: At baseline, modified GOLD criteria were met by 610 (9.1%) participants, 519 (85.1%) of whom had stage 1 COPD. At follow-up, individuals with symptomatic stage 1 COPD (n = 224) had a faster decline in FEV1 (−9 ml/year (95% CI −13 to −5)), increased respiratory care utilisation (OR 1.6 (95% CI 1.0 to 2.6)) and a lower quality of life than asymptomatic subjects with normal lung function (n = 3627, reference group). In contrast, individuals with asymptomatic stage 1 COPD (n = 295) had no significant differences in FEV1 decline (−3 ml/year (95% CI −7 to +1)), respiratory care utilisation (OR 1.05 (95% CI 0.63 to 1.73)) or quality of life scores compared with the reference group. Conclusions: In population-based studies, respiratory symptoms are of major importance for predicting long-term clinical outcomes in subjects with COPD with mild obstruction. Population studies based on spirometry only may misestimate the prevalence of clinically relevant COPD.