Sensitivity For Detection Of Ischemia Research Articles

Detection of brief atrial fibrillation in continuous 12-lead ECG recordings using an algorithm for computerized resting ECG interpretation combined with convolutional neural network for reducing false detections

Existing criteria recommended by ACC/ESC for identifying patients with ST elevation myocardial infarction (STEMI) from the 12-lead ECG perform with high specificity (SP), but low sensitivity (SE). In our previous studies, we found that the SE of ischemia detection can be markedly improved without any loss of SP by calculating, from the 12-lead ECG, ST deviation in 3 “optimal” vessel-specific leads (VSLs). Our original VSLs, based on ΔST body-surface potential maps (BSPMs), have been modified by using the more appropriate J-point BSPMs at peak ischemia (without subtraction of pre-occlusion distributions). The aim of the present study was to compare the performance of these new VSLs with that achieved by the STEMI criteria used in current practice.Two independent datasets of 12-lead ECGs were used: the STAFF III dataset acquired during ischemic episodes caused by balloon inflation in LAD (n = 35), RCA (n = 47), and LCx (n = 17) coronary arteries, and the Glasgow dataset comprising admission 12-lead ECGs of 116 patients who were hospitalized for chest pain and underwent contrast-enhanced cardiac MRI that confirmed AMI in 58 patients (50%).We found that, in the STAFF III dataset, the detection of ischemic state by the STEMI criteria attained SE/SP of 60/97%, whereas SE/SP values of VSLs were 72/98%. In the Glasgow dataset, STEMI criteria yielded SE/SP of 43/98%, whereas the VSLs improved SE/SP to 60/98%. The most significant increase in diagnostic performance appeared in patients with LCx coronary artery occlusion: in STAFF III data (n = 17) SE achieved by STEMI criteria was improved by the VSLs from 35% to 71%; in Glasgow data (n = 12) SE of 31% achieved by STEMI criteria was improved by the VSLs to 69%.In our study population, existing ACC/ESC STEMI criteria complemented by the new VSLs yielded much improved sensitivity of ischemia detection without any detrimental effect on specificity. This finding needs to be corroborated on a larger chest-pain patient population with typical prevalence of acute ischemia presented to the emergency rooms.

Validation of improved vessel-specific leads (VSLs) for detecting acute myocardial ischemia

BackgroundExisting criteria recommended by ACC/ESC for identifying patients with ST elevation myocardial infarction (STEMI) from the 12-lead ECG perform with high specificity (SP), but low sensitivity (SE). In our previous studies, we found that the SE of ischemia detection can be markedly improved without any loss of SP by calculating, from the 12-lead ECG, ST deviation in 3 “optimal” vessel-specific leads (VSLs). Our original VSLs, based on ΔST body-surface potential maps (BSPMs), have been modified by using the more appropriate J-point BSPMs at peak ischemia (without subtraction of pre-occlusion distributions). The aim of the present study was to compare the performance of these new VSLs with that achieved by the STEMI criteria used in current practice. MethodsTwo independent datasets of 12-lead ECGs were used: the STAFF III dataset acquired during ischemic episodes caused by balloon inflation in LAD (n=35), RCA (n=47), and LCx (n=17) coronary arteries, and the Glasgow dataset comprising admission 12-lead ECGs of 116 patients who were hospitalized for chest pain and underwent contrast-enhanced cardiac MRI that confirmed AMI in 58 patients (50%). ResultsWe found that, in the STAFF III dataset, the detection of ischemic state by the STEMI criteria attained SE/SP of 60/97%, whereas SE/SP values of VSLs were 72/98%. In the Glasgow dataset, STEMI criteria yielded SE/SP of 43/98%, whereas the VSLs improved SE/SP to 60/98%. The most significant increase in diagnostic performance appeared in patients with LCx coronary artery occlusion: in STAFF III data (n=17) SE achieved by STEMI criteria was improved by the VSLs from 35% to 71%; in Glasgow data (n=12) SE of 31% achieved by STEMI criteria was improved by the VSLs to 69%. ConclusionIn our study population, existing ACC/ESC STEMI criteria complemented by the new VSLs yielded much improved sensitivity of ischemia detection without any detrimental effect on specificity. This finding needs to be corroborated on a larger chest-pain patient population with typical prevalence of acute ischemia presented to the emergency rooms.

Transient Global Amnesia. Evidence against vascular ischemic etiology from diffusion weighted imaging.

The etiology of Transient Global Amnesia (TGA) is still obscure. Diffusion-Weighted-Imaging (DWI) provides conflicting evidence concerning a possible vascular ischemic cause in mesiotemporal structures including the hippocampal region. The question remains open whether conflicting observations resulted from different observation times. DWI was performed at a time interval with known sensitivity for detection of ischemia. Ten patients (5 male, 5 female; mean age of 63 +/- 9, range 41-71 years) with typical TGA were investigated at an average delay of 18 hours (range 6 to 44 hours) between onset of symptoms and magnetic resonance imaging (transversal DW-, T1W- and T2W-MRI). Five patients received apparent-diffusion-coefficient (ADC)-mapping. Cerebrovascular studies (ECG, TTE and extra/transcranial dopplersonographic and duplexultrasonic investigation) and EEG were normal in all patients. DW-MRI-sequences and ADC-maps, if performed, were normal in all patients. Conventional T2W-MRI in 3 out of 10 patients showed microangiopathic subcortical changes and lacunar strokes of older origin. We conclude that TGA does not result from a vascular ischemic etiology in the majority of cases.

Significance of Slow Upsloping ST-Segment Depression on Exercise Stress Testing

The supplementary value of varying degrees of upsloping ST-segment depression observed during treadmill exercise testing to the accuracy of the exercise ST-segment response for detection of ischemia was determined by employing a reversible thallium-201 (201Tl) defect as the criteria for ischemia. A group of 199 consecutive patients (168 men) with ≥1 reversible 201Tl defects on quantitative planar perfusion imaging, and a normal group of 366 patients with normal 201Tl scans who achieved ≥85% of age-predicted maximum heart rate were studied. Upsloping ST-segment depression was subcategorized for ≥1.0, ≥1.5, and ≥2.0 mm of sustained ST-segment depression below baseline at 0.08 seconds after the J-point. If only ≥1.0 mm of horizontal or downsloping ST-segment depression was designated as abnormal and all upsloping responses as normal, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the exercise electrocardiogram were 49% (98 of 199), 84% (281 of 336), 64% (98 of 153), 74% (281 of 382), and 71% (379 of 535), respectively. If in addition to >1.0 mm of horizontal or downsloping ST-segment depression, ≥2.0 mm of upsloping ST-segment depression is considered abnormal, these values were 52% (104 of 199), 81% (272 of 336), 62% (104 of 168), 74% (272 of 367), and 70% (376 of 535), respectively. If ≥1.5 mm of upsloping ST-segment depression is considered an abnormal response, these values were 59% (117 of 199), 74% (248 of 336), 57% (117 of 205), 75% (248 of 330), and 68% (365 of 535), respectively. Finally, if ≥1.0 mm of upsloping ST-segment depression is considered abnormal, these values were 71% (142 of 199), 56% (187 of 336), 49% (142 of 291), 77% (187 of 244), and 61% (329 of 535), respectively. Thus, if upsloping ST-segment depression is added to the criteria for a positive exercise test result, sensitivity for detection of ischemia is increased but at the expense of a fall in specificity and a significant decrease in the positive predictive value of the test.The significance of ≥1.0 mm of upsloping ST-segment depression on exercise testing for detection of inducible ischemia was evaluated in 199 patients with thallium-201 (201Tl) redistribution and 366 patients with normal scans on exercise 201Tl scintigraphy. When upsloping ST-segment depression is added to the criteria for a positive exercise test for ischemia, sensitivity is increased (from 49% to 71%) but at the expense of a fall in specificity (84% to 56%), yielding an unacceptably low positive predictive value of 49% for identification of patients with reversible exercise-induced ischemia.

Assessing prognosis after acute myocardial infarction in the thrombolytic era.

The use of physiologic testing for prognostication continues to be useful and widely applied in the predischarge evaluation of patients recovering from an uncomplicated acute myocardial infarction in the thrombolytic era. Because patients with abnormal exercise test results are now routinely sent for angiography, there are no randomized trials or experimental confirmation that exercise parameters are still associated with the same prognostic value in the thrombolytic era. Nevertheless, the excellent outcomes in patients treated with thrombolytic therapy and risk stratified with exercise testing provide strong empiric support for the continued use of noninvasive testing of patients without complications after thrombolytic therapy. Reviews of patient cohorts enrolled in trials of thrombolytic therapy show that these patients have a lower incidence of multivessel disease and less evidence of ischemia (ST segment depression or thallium 201 redistribution) compared with prethrombolytic cohorts. For this and other reasons, the sensitivity and specificity of exercise variables for prognosis or detection of multivessel disease are not as strong. The addition of perfusion imaging will enhance the sensitivity for detection of ischemia within or remote from the infarct zone and will provide information regarding viability. Patients who are unable to exercise or those with poor exercise tolerance, an abnormal exercise blood pressure response, inducible ischemia, or nonsustained ventricular tachycardia are candidates for further invasive evaluation and consideration for coronary revascularization. With 201Tl imaging, evidence for increased pulmonary uptake of the tracer is indicative of high risk and a high probability of an adverse outcome with medical therapy. Low-risk patients are those who achieve their target heart rate or work load without inducible angina, ST segment depression, reversible perfusion abnormalities, or increased lung 201Tl uptake. Defect size is reflective of infarct size, and patients with extensive areas of nonreversible hypoperfusion are also at high risk for future events even in the absence of ischemia. Finally, pharmacologic stress imaging with dipyridamole, adenosine, or dobutamine has been found to be safe when employed for stress testing soon after uncomplicated infarction.