t ACUTE MORTALITY AND CHF
Fig. 1. Factors contributing to increased mortality in diabetic patients with acute MI.
all patients received fibrinolytic agents, show a 30-100% higher in-hospital mortality in diabetic patients compared to nondiabetics.
It appears that, although concomitant risk factors such as advanced age, history of hypertension, hyperlipidemia and increased body mass index may exert a confounding effect and contribute to a decreased survival post-MI, diabetes per se exerts an independent negative role, as consistently documented in all studies.
Mechanisms for increased mortality are shown in figure 1. Interestingly these data obtained in multicenter randomized studies, where selected patients usually receive state-of-the-art treatment, leading often to mortality rates well below the one observed in the general population, have been confirmed by observational studies where mortality rates more closely reflect those observed in current clinical practice. In the Finmonica study, 45.1% diabetic men and 38.8% diabetic women with their first MI died within 1 year, as compared to 32.6 and 20.2% in nondiabetic patients. A substantial proportion of these deaths occurred out of hospital soon after the onset of symptoms.
Survival is closely linked to residual left ventricular pump function following acute MI. The increased susceptibility to cardiac failure (a 4-fold increase for women in the Framingham Study) is an important factor in reducing survival in diabetics. Two factors may explain the increased incidence of heart failure post-MI. First, more severe and diffuse coronary disease limits the coronary reserve causing noninfarcted segments to be rendered more ischemic by an infarct of comparable size. Secondly, coexistent diabetic cardiomyopathy, which is independent of the coronary disease, impairs myocardial relaxation and contractility.
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