Baroreflex sensitivity predicts long-term cardiovascular mortality after myocardial infarction even in patients with preserved left ventricular function.
ABSTRACT This study sought to assess the long-term predictive power of depressed baroreflex sensitivity (BRS) among post-myocardial infarction (MI) patients with preserved left ventricular function.
Risk stratification after MI is primarily performed by identifying patients with depressed left ventricular ejection fraction (LVEF) because of their greater mortality. Autonomic markers can help refining risk stratification. Depressed BRS (<3 ms/mm Hg) correlated with cardiovascular mortality in 1,284 post-MI patients during a 21-month follow-up in the multicenter ATRAMI (Autonomic Tone and Reflexes After Myocardial Infarction) study, but had no significant predictive power in patients with LVEF >35% or above age 65 years.
Two hundred forty-four consecutive post-MI patients (age 59 +/- 10 years) with LVEF >35% (average 54 +/- 8%) were enrolled. They underwent a complete assessment, including BRS 4 weeks after MI.
During a 5-year mean follow-up, 14 (5.7%) patients died of cardiovascular causes. Multivariate analysis identified BRS (p = 0.0001), but not LVEF and age, as predictive of cardiovascular mortality. The relative risk (95% confidence interval [CI]) for depressed BRS was 11.4 (95% CI 3.3 to 39.0) for the overall population, 19.6 (95% CI 4.1 to 94.8) for patients </=65 years, and 7.2 (95% CI 1.3 to 39.9) for patients above age 65.
Even among the large number of low-risk post-MI patients with preserved left ventricular function, depressed BRS identifies, independently of age, a subgroup at long-term high risk for cardiovascular mortality in which more aggressive preventive strategies should be considered.
Article: Antecedent hypoglycemia impairs autonomic cardiovascular function: implications for rigorous glycemic control.[show abstract] [hide abstract]
ABSTRACT: Glycemic control decreases the incidence and progression of diabetic complications but increases the incidence of hypoglycemia. Hypoglycemia can impair hormonal and autonomic responses to subsequent hypoglycemia. Intensive glycemic control may increase mortality in individuals with type 2 diabetes at high risk for cardiovascular complications. We tested the hypothesis that prior exposure to hypoglycemia leads to impaired cardiovascular autonomic function. Twenty healthy subjects (age 28 +/- 2 years; 10 men) participated in two 3-day inpatient visits, separated by 1-3 months. Autonomic testing was performed on days 1 and 3 to measure sympathetic, parasympathetic, and baroreflex function. A 2-h hyperinsulinemic [hypoglycemic (2.8 mmol/l) or euglycemic (5.0 mmol/l)] clamp was performed in the morning and in the afternoon of day 2. Comparison of the day 3 autonomic measurements demonstrated that antecedent hypoglycemia leads to 1) reduced baroreflex sensitivity (16.7 +/- 1.8 vs. 13.8 +/- 1.4 ms/mmHg, P = 0.03); 2) decreased muscle sympathetic nerve activity response to transient nitroprusside-induced hypotension (53.3 +/- 3.7 vs. 40.1 +/- 2.7 bursts/min, P < 0.01); and 3) reduced (P < 0.001) plasma norepinephrine response to lower body negative pressure (3.0 +/- 0.3 vs. 2.0 +/- 0.2 nmol/l at -40 mmHg). Baroreflex sensitivity and the sympathetic response to hypotensive stress are attenuated after antecedent hypoglycemia. Because impaired autonomic function, including decreased cardiac vagal baroreflex sensitivity, may contribute directly to mortality in diabetes and cardiovascular disease, our findings raise new concerns regarding the consequences of hypoglycemia.Diabetes 01/2009; 58(2):360-6. · 8.29 Impact Factor
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ABSTRACT: This study deals with cardiovascular autonomic neuropathy (CAN) in type 1 diabetic patients and its association with other complications. We searched for CAN in 684 patients (age, 47 +/- 12 years; diabetes duration, 22 +/- 11 years) by cardiovascular responses to deep breathing and standing. Patients considered as positive had laboratory evaluation: "Ewing" tests (deep breathing, Valsalva, stand test, hand grip); heart rate variability (HRV) [low frequency (LF) and high frequency (HF) power] and spontaneous baroreflex slope (SBS). Logistic regression was used to identify the combination of patient characteristics, including other complications, most associated with CAN severity according to Ewing Score (ES 0-5). 66.2% presented no significant abnormality (ES 0-0.5), 21.5 % had mild abnormalities (ES 1-2), and 12.3% had confirmed autonomic failure (ES > 2). Decrease in LF, HF and SBS was highly correlated to CAN severity. In the stepwise regression, age, retinopathy, nephropathy, bladder dysfunction, erectile dysfunction, peripheral neuropathy and hypertension remained correlated with CAN, whereas digestive neuropathy, BMI and HbA1c were excluded. Despite a small number of events, we found a significant association between coronary disorders and CAN severity. Simple bedside tests can detect CAN. HRV and SBS provide additional elements on CAN severity. Diabetes duration did not discriminate sufficiently patients with CAN. The association with retinopathy is in favor of the role of poor glycemic control in CAN development. This study shows the interest of CAN detection and the need to look for extracardiac autonomic neuropathy and silent myocardial ischemia in patients with confirmed CAN.Clinical Autonomic Research 03/2010; 20(3):153-60. · 1.30 Impact Factor
Conference Proceeding: Impaired baroreflex sensitivity predicts mortality in chronic kidney disease[show abstract] [hide abstract]
ABSTRACT: Autonomic nervous system dysfunction is common in patients with chronic kidney disease (CKD) and is associated with adverse cardiovascular (CV) outcomes and mortality in non-CKD populations, but has not previously been shown to predict all cause mortality in CKD. 134 patients were recruited to an observational study. CV structure, function and inflammatory status were quantified. Survival was assessed at 4 years. There were 38 fatalities. Unadjusted Cox-regression analysis demonstrated lowest fertile baroreflex sensitivity (BRS) increased mortality risk by 2.43x. Stepwise multivariate analysis showed that this effect was independent of age, inflammation and vascular calcification. Reduced BRS is common in CKD, however even within such a population lowest values were still independently associated with additional mortality.Computers in Cardiology, 2008; 10/2008