Diagnostic value of ST-segment deviations during cardiac exercise stress testing: Systematic comparison of different ECG leads and time-points.

BACKGROUND: Exercise ECG stress testing is the most widely available method for evaluation of patients with suspected myocardial ischemia. Its major limitation is the relatively poor accuracy of ST-segment changes regarding ischemia detection. Little is known about the optimal method to assess ST-deviations. METHODS: A total of 1558 consecutive patients undergoing bicycle exercise stress myocardial perfusion imaging (MPI) were enrolled. Presence of inducible myocardial ischemia was adjudicated using MPI results. The diagnostic value of ST-deviations for detection of exercise-induced myocardial ischemia was systematically analyzed 1) for each individual lead, 2) at three different intervals after the J-point (J+40ms, J+60ms, J+80ms), and 3) at different time points during the test (baseline, maximal workload, 2min into recovery). RESULTS: Exercise-induced ischemia was detected in 481 (31%) patients. The diagnostic accuracy of ST-deviations was highest at +80ms after the J-point, and at 2min into recovery. At this point, ST-amplitude showed an AUC of 0.63 (95% CI 0.59-0.66) for the best-performing lead I. The combination of ST-amplitude and ST-slope in lead I did not increase the AUC. Lead I reached a sensitivity of 37% and a specificity of 83%, with similar sensitivity to manual ECG analysis (34%, p=0.31) but lower specificity (90%, p<0.001). CONCLUSION: When using ECG stress testing for evaluation of patients with suspected myocardial ischemia, the diagnostic accuracy of ST-deviations is highest when evaluated at +80ms after the J-point, and at 2min into recovery.

Diagnostic and Prognostic Value of Lead aVR During Exercise Testing in Patients Suspected of Having Myocardial Ischemia.

We aimed to assess the diagnostic and prognostic value of ST-segment deviation in aVR, a lead often ignored in clinical practice, during exercise testing and to compare it to the most widely used criterion of ST-segment depression in V5. We enrolled 1,596 patients with suspected myocardial ischemia referred for nuclear perfusion imaging undergoing bicycle stress testing. ST-segment amplitudes in leads aVR and V5 were automatically measured. The presence of inducible myocardial ischemia was the diagnostic end point and adjudicated based on nuclear perfusion imaging and coronary angiography. Major adverse cardiac events (MACE) during 2 years of follow-up including death, acute myocardial infarction, and coronary revascularization were the prognostic end point. Exercise-induced myocardial ischemia was detected in 470 patients (29%). Median ST amplitudes for leads aVR and V5 differed significantly among patients with and without ischemia (p <0.01). The diagnostic accuracy of ST changes for myocardial ischemia as quantified by the area under the receiver operating characteristic curve was highest 2 minutes into recovery and similar in aVR and V5 (0.62, 95% confidence interval CI 0.60 to 0.65 vs 0.60, 95% confidence interval 0.58 to 0.63, p = 0.08 for comparison). In multivariate analysis, ST changes in lead aVR, but not lead V5, contributed independent diagnostic information on top of clinical parameters and manual electrocardiographic interpretation. Within 2 years of follow-up, MACE occurred in 33% of patients with ST elevations in aVR and in 16% without (p <0.001). In conclusion, ST elevation in lead aVR during exercise testing indicates inducible myocardial ischemia independently of ST depressions in lead V5 and clinical factors and also predicts MACE during follow-up.

Impact of high-sensitivity cardiac troponin on use of coronary angiography, cardiac stress testing, and time to discharge in suspected acute myocardial infarction.

AIMS: High-sensitivity cardiac troponin (hs-cTn) assays provide higher diagnostic accuracy for acute myocardial infarction (AMI) when compared with conventional assays, but may result in increased use of unnecessary coronary angiographies due to their increased detection of cardiomyocyte injury in conditions other than AMI. METHODS AND RESULTS: We evaluated the impact of the clinical introduction of high-sensitivity cardiac troponin T (hs-cTnT) on the use of coronary angiography, stress testing, and time to discharge in 2544 patients presenting with symptoms suggestive of AMI to the emergency department (ED) within a multicentre study either before (1455 patients) or after (1089 patients) hs-cTnT introduction. Acute myocardial infarction was more often the clinical discharge diagnosis after hs-cTnT introduction (10 vs. 14%, P < 0.001), while unstable angina less often the clinical discharge diagnosis (14 vs. 9%, P = 0.007). The rate of coronary angiography was similar before and after the introduction of hs-cTnT (23 vs. 23%, P = 0.092), as was the percentage of coronary angiographies showing no stenosis (11 vs. 7%, P = 0.361). In contrast, the use of stress testing was substantially reduced from 29 to 19% (P < 0.001). In outpatients, median time to discharge from the ED decreased by 79 min (P < 0.001). Mean total costs decreased by 20% in outpatients after the introduction of hs-cTnT (P = 0.002). CONCLUSION: The clinical introduction of hs-cTn does not lead to an increased or inappropriate use of coronary angiography. Introduction of hs-cTn is associated with an improved rule-out process and thereby reduces the need for stress testing and time to discharge. CLINICAL TRIAL REGISTRATION INFORMATION: www.clinicaltrials.gov. Identifier, NCT00470587.

Direct comparison of cardiac troponin I and cardiac troponin T in the detection of exercise-induced myocardial ischemia.

BACKGROUND: It is unknown, whether cardiac troponin (cTn) I or cTnT is the preferred biomarker in the detection of exercise-induced myocardial ischemia. METHODS: We investigated patients with suspected myocardial ischemia referred for exercise or pharmacological rest/stress myocardial perfusion single-photon emission computed tomography (SPECT) to directly compare the diagnostic accuracy of high-sensitivity cTnI (hs-cTnI) and hs-cTnT. Diagnostic performance was analyzed separately according to stress modality. Hs-cTnI and hs-cTnT were measured before, immediately after, as well as 2h and 4h after maximal exercise in a blinded fashion. Further, all clinical information available to the treating cardiologist was used to quantify the clinical judgment regarding the presence of myocardial ischemia using a visual analog scale twice: once prior and once after stress-testing. The presence of stress-induced myocardial ischemia was adjudicated using SPECT combined with coronary angiography findings. RESULT: A total of 403 consecutive patients were enrolled in our study, of which 229 underwent exercise stress and 174 patients pharmacological stress. Exercise-stress-induced myocardial ischemia was detected in 90 patients (39.3% of 229). Levels of hs-cTnI and hs-cTnT were both significantly higher at all time-points examined in patients with exercise-induced myocardial ischemia as compared to patients without myocardial ischemia (all p<0.001). Correlation of hs-cTnI and hs-cTnT was high in direct comparison of time-points (Spearman's rho all ≥0.7). The AUCs for baseline/peak/2h/4h for hs-cTnI and hs-cTnT were 0.71/0.71/0.72/0.69 vs. 0.74/0.73/0.71/0.72, respectively (all p=ns for hs-cTnI versus hs-cTnT). In patients undergoing pharmacological stress, the AUCs for baseline/peak/2h/4h for hs-cTnI and hs-cTnT were 0.66/0.66/0.68/0.67 and 0.61/0.62/0.64/0.59, respectively (all p=ns for hs-cTnI versus hs-cTnT). Also the combinations including clinical judgment or changes during serial sampling were similar for hs-cTnI and hs-cTnT (all p=ns). CONCLUSIONS: Hs-cTnI and hs-cTnT provide comparable diagnostic information regarding exercise-induced myocardial ischemia. Overall, their diagnostic accuracy seems moderate. UNIQUE IDENTIFIER: NCT01838148.

One-hour rule-in and rule-out of acute myocardial infarction using high-sensitivity cardiac troponin I.

UNLABELLED: We aimed to prospectively derive and validate a novel 0-/1-hour algorithm using high-sensitivity cardiac troponin I (hs-cTnI) for the early "rule-out" and "rule-in" of acute myocardial infarction (AMI). METHODS: In a prospective multicenter diagnostic study, we enrolled 1,500 patients presenting with suspected AMI to the emergency department. The final diagnosis was centrally adjudicated by 2 independent cardiologists blinded to hs-cTnI concentrations. The hs-cTnI (Siemens Vista) 0-/1-hour algorithm incorporated measurements performed at baseline and absolute changes within 1 hour, was derived in the first 750 patients (derivation cohort), and then validated in the second 750 (validation cohort). RESULTS: Overall, AMI was the final diagnosis in 16% of patients. Applying the hs-cTnI 0-/1-hour algorithm developed in the derivation cohort to the validation cohort, 57% of patients could be classified as "rule-out"; 10%, as "rule-in"; and 33%, as "observe." In the validation cohort, the sensitivity and the negative predictive value for AMI in the "rule-out" zone were 100% (95% CI 96%-100%) and 100% (95% CI 99%-100%), respectively. The specificity and the positive predictive value (PPV) for AMI in the "rule-in" zone were 96% (95% CI 94%-97%) and 70% (95% CI 60%-79%), respectively. Negative predictive value and positive predictive value of the 0-/1-hour algorithm were higher compared to the standard of care combining hs-cTnI with the electrocardiogram (both P < .001). CONCLUSION: The hs-cTnI 0-/1-hour algorithm performs very well for early rule-out as well as rule-in of AMI. The clinical implications are that used in conjunction with all other clinical information, the 0-/1-hour algorithm will be a safe and effective approach to substantially reduce time to diagnosis.