Abstract 1408: Acute Myocardial Infarction in Men and Women: Association with Adverse Prognostic Indicators
Background: Following acute myocardial infarction (AMI), an impaired baroreceptor reflex sensitivity controlling the heart period through the vagus nerves (BRS) and sympatho-humoral activation have been associated with adverse outcome. Normal women are reported to have a lower BRS and sympathetic activity relative to men. Because AMI in women (F-AMI) results in greater acute mortality and complications (particularly heart failure and cardiogenic shock) than in men (M-AMI), the present study was planned to determine whether F-AMI patients have greater central sympathetic output and BRS impairment than M-AMI patients.
Methods: We examined four groups of subjects; 21 F-AMI, 21 M-AMI patients 2– 4 days following AMI and 21 normal control women (F-NC) and 21 men (M-NC). The groups were matched (Table⇓) according to age, body mass index (BMI) and waist circumference (WC). The two AMI groups were also matched for heart rate (HR) and mean arterial pressure (MAP), and had similar AMI details and management. Muscle sympathetic nerve activity (MSNA) was measured by microneurography from the peroneal nerve and quantified as bursts per 100 cardiac beats (b/100b). BRS was obtained from the Valsalva maneuver as the steepest slope between the RR interval (msec) and systolic pressure (mmHg). Data were expressed as mean ± SEM.
Results: MAP (at least p<0.05; ANOVA post-tests) and HR were lower in the AMI groups than in control groups. MSNA was significantly greater (at least p<0.05) and BRS lower (at least p<0.01) in the 2 AMI than in the corresponding control groups. The MSNA hyperactivity in F-AMI was similar to that in M-AMI, while BRS was more impaired (P<0.05) in F-AMI than M-AMI.
Conclusion: These results in patients following AMI show that women attained similar sympathetic activation and greater BRS impairment than men. The findings may partly explain the worse outcome in women during the acute phase following AMI in terms of acute mortality and complications.