The prognostic value of pulsatility index, flow velocity, and their ratio, measured with TCD ultrasound, in patients with a recent TIA or ischemic stroke
Background- Increased flow velocities, and combinations of low mean flow velocity (MFV) and a high pulsatility index (PI) are associated with intracranial arterial disease. We investigated the association of MFV and the ratio of PI and MFV (PI-MFV ratio) in the middle cerebral artery (MCA) with recurrence of vascular events in patients with a transient ischemic attack (TIA) or minor ischemic stroke. Methods- Five hundred and ninety-eight consecutive patients underwent TCD investigation. Outcome events were fatal or non-fatal stroke and the composite of stroke, myocardial infarction, or vascular death (major vascular events). Hazard ratios (HR) were estimated with Cox proportional hazards multiple regression method, adjusted for age, gender, and vascular risk factors. Results- TCD registration was successful in 489 patients. Mean follow-up was 2.1years. Cumulative incidence was 9% for all stroke and 12% for major vascular events. MFV over 60.5cm/s increased the risk for both stroke (HR 2.8; 95% CI: 1.3-6.0) and major vascular events (HR 2.6; 95% CI: 1.3-5.0). Each unit increase in PI-MFV ratio was associated with a HR 2.8 (95% CI: 1.7-4.8) for stroke and HR 2.2 (95% CI: 1.3-3.6) for major vascular events. Conclusion- In patients with a TIA or non-disabling ischemic stroke, MFV and the PI-MFV ratio in the MCA are independent prognostic factors for recurrent vascular events.