Middle Cerebral Artery Stenosis Increased the Risk of Vascular Disease Mortality among Type 2 Diabetic Patients

BACKGROUND: In Chinese populations, middle cerebral artery (MCA) stenosis is the most commonly identified intracranial vascular lesion, and has been shown to be associated with an increased risk of secondary stroke mortality, but has yet to be reported for primary events. We assess whether asymptomatic MCA stenosis is associated with mortality in Chinese type 2 diabetic patients. METHODS: The presence of MCA stenosis was determined by transcranial Doppler and mortality data were collated in the Hong Kong Death Registry. Cox proportional hazards regression was used to determine if the MCA stenosis (n = 272, 53.7% 2-vessel disease) in 2,197 diabetics was associated with all-cause or vascular disease mortality, including after adjustment for conventional vascular risk factors. Anthropometric and fasting biochemical parameters were compared between diabetic patients with MCA stenosis and without evidence of stenosis. RESULTS: A total of 191 deaths were identified (30.9% of vascular disease origin) during a follow-up of 18,279 patient years over 8.32 years. After adjustment for age, gender and diabetes duration, the hazard ratios for vascular mortality for 1- and 2-vessel disease were 2.47 (95% CI = 1.13-5.38) and 4.47 (95% CI = 2.24-8.82), p <0.001 for trend, for increasing vascular mortality with increasing severity of cerebrovascular involvement, but 0.81 (95% CI = 0.45-1.47) and 2.23 (95% CI = 1.45-1.47), p = 0.001 for trend, for all-cause mortality. For vascular mortality, further adjustments for anthropometric and fasting biochemical parameters, or existing disease and treatment history increased the hazard ratios for 1-vessel disease slightly but attenuated the risk for 2-vessel disease evidently, 2.81 (95% CI = 1.10-7.16) and 2.85 (95% = CI 1.11-7.33), p = 0.026. CONCLUSION: The presence of MCA stenoses was an independent predictor of vascular mortality in these diabetics. More aggressive treatment of risk factors in these subjects merits further evaluation.