Real-time rapid acuity assessment using VEPs: development and validation of the step VEP technique.

PURPOSE: To develop a reference range of visual acuities corresponding to thresholds found using the step VEP method of rapid, objective visual acuity assessment by using steady state (ss)VEPs in normal adults. METHODS: Sixteen normal adults had visual acuity assessed five times with both the step VEP and with Glasgow Acuity Cards (GAC). Subjects were tested once without filters and with four different levels of optical filtering provided by Bangerter neutral-density filters. Acuity outcomes were compared by linear regression and Bland-Altman analysis. RESULTS: Step VEP and GAC acuities correlated highly (r(2) = 0.60, P = 0.000). GAC scores were predicted with the equation: acuity(GAC) = (0.9 x acuity(step VEP)) - 0.37. Step VEP acuity was 0.46 (95% CI: -0.13 to 1.06) logMAR units greater (poorer) than GAC acuities in these normal subjects. The disparity between test results did not vary with visual acuity. CONCLUSIONS: The step VEP provides a rapid, objective means of estimating visual acuity that can be related to acuity derived from a commonly used letter test.

ST-segment deviation analysis of the admission 12-lead electrocardiogram as an aid to early diagnosis of acute myocardial infarction with a cardiac magnetic resonance imaging gold standard.

OBJECTIVES: The purpose of this study was to validate existing 12-lead electrocardiographic (ECG) ST-segment elevation myocardial infarction (STEMI) criteria in the diagnosis of acute myocardial infarction (AMI) and the application of similar ST-segment depression (STEMI-equivalent) criteria with contrast-enhanced cardiac magnetic resonance imaging (ceMRI) as the diagnostic gold standard. BACKGROUND: The admission ECG is the cornerstone in the diagnosis of AMI, and ceMRI is a new diagnostic gold standard that can be used to validate existing and novel 12-lead ECG criteria. METHODS: One hundred fifty-one consecutive patients with their first hospital admission for chest pain underwent ceMRI. The 116 patients without ECG confounding factors were included in this study, and AMI was confirmed in 58 (50%). The admission ECG was evaluated on the basis of the lead distribution of ST-segment deviation according to current American College of Cardiology/European Society of Cardiology (ACC/ESC) guidelines. RESULTS: A sensitivity of 50% and specificity of 97% for AMI were achieved with the currently applied ST-segment elevation criteria. Consideration of ST-segment depression in addition to elevation increased sensitivity for detection of AMI from 50% to 84% (p < 0.0001) but only decreased specificity from 97% to 93% (p = 0.50). There were no significant differences in AMI location or size between patients meeting the 12-lead ACC/ESC ST-segment elevation criteria and those only meeting the ST-segment depression criteria. CONCLUSIONS: In patients admitted to hospital with possible AMI, the consideration of both ST-segment elevation and depression in the standard 12 lead-ECG recording significantly increases the sensitivity for the detection of AMI with only a slight decrease in the specificity.