11. Summary Of Overall MCG Data For The Detection Of Relevant Coronary Stenosis. n = number of cases; TP = true positives; TN = true negatives; FP = false positives; FN = false negatives; a priori = a priori probability of stenosis; Correct = fraction of correctly predicted cases; Sens = sensitivity; Spec = specificity; PPV = positive predictive value; NPV = negative predictive value; LR+ = positive likelihood ratio; LR- = negative likelihood ratio; OR = odds ratio; ROC AUC = receiver operating curve area under the curve for continuous severity score; 95% CI = 95% confidence interval; Lower = Lower boundary of 95% CI; Upper = Upper boundary of 95% CI; NaN = not a number; Revasc = coronary revascularization in medical history. Meta Analysis table
16. A Tertiary Center Angiogram population - Disease Severity Distribution
17.
Editor's Notes
MCG was investigated in 3 prospective clinical studies in the US (single center, enrollment in 2000), Germany (single center, enrollment 2001-2003), and Asia (4 centers, enrollment 2004). This slide gives an overview of the studies. In all studies MCG was compared to coronary angiography. All angiographies were re-read and confirmed by an independent angiographer. If a second reading was not possible, patients were excluded, as discussed later. Investigators were blinded against the respective other method. All studies were monitored by independent study monitors.
The first prospective trial was done at the Westchester Medical Center, Valhalla, NY. Patients were enrolled in 2000. Only patients without previous revascularization were included who were scheduled for coronary angiography. Angiography results were scored use a quantitative (geometric) scoring system (BARI; Alderman et al, Coron Artery Dis. 1992;3:1189-1207). Angiography results for 40% coronary stenosis and for 60% coronary stenosis (according to BARI scoring values) were compared to MCG and a 12-lead computer-aided resting ECG diagnosis system. At the time of the study only the qualitative MCG diagnosis for cardiac ischemia was available. The study was published (peer reviewed) in Heart Dis 2002;4:2-12 by Melvin B. Weiss et al.
This table shows the results of MCG and ECG findings compared to angiography results. n = number of patients TP = true positive TN = true negative FP = false positive FN = false negative Sens = sensitivity Spec = specificity PPV = positive predictive value (adjusted for a priori probability) NPV = negative predictive value (adjusted for a priori probability) Correct = correctly classified cases of total study population a priori = incidence of coronary stenosis (as identified in angiography) = a priori probability of the diagnosis in this study population
The second prospective single-center trial was done in Siegburg between Summer 2001 and Summer 2003. A total of 775 patients scheduled for coronary angiography were enrolled. Of these patients 213 had a history of coronary revascularization. 24 patients had to be excluded because of poor ECG tracings (= 3%). Angiograms were classified immediately by the respective angiographer and independently by a second interventional cardiologist within 4 weeks after the angiogram. If the two investigators did not agree on the results, they discussed the angiograms until agreement was reached. Coronary stenosis in the angiogram was classified as hemodynamically relevant, if a stenosis of > 70% in at least one vessel or a stenosis of > 50% in the left main coronary artery was detected. MCG tests were done shortly (typically less than 2 hours) before the angiography. The continuous MCG severity score was calculated as part of the MCG analysis. It has a theoretical range from 0 to 20, where higher values relate to a higher probability of myocardial ischemia from coronary disease. A score of 4 or higher is considered indicative of hemodynamically relevant coronary stenosis. In addition, a risk factor model (binary logistic regression) was calculated from know CAD risk factors for 595 patients were complete risk factor information was available (discussed later; 423 patients without and 172 patients with prior revascularization within more than 6 weeks before enrollment). Results from this study were presented at Chest 2007 and at the AHA Scientific Sessions 2007. A detailed analysis including the risk factor models was published separately for patient without and with revascularization in Int J Med Sci.
ROC curves for the continuous MCG score for the detection of coronary stenosis. For all patients ROC AUC = 0.873 (95% CI 0.846-0.900). No significant differences in ROC between sex and age groups. Similar ROC also for sex/age subgroups and revascularization, type of revascularization and no revascularization.
This table shows the results for MCG compared to angiography for the detection of hemodynamically relevant coronary stenosis. High sensitivity and specificity as well as predictive values in the entire population and in all subgroups, especially in elderly patients. The risk factor model alone did not show strong predictive power. The addition of information about previous myocardial infarction did not chance this, nor does it affect the MCG diagnostic performance. n = number of patients a priori = incidence of coronary stenosis (as identified in angiography) = a priori probability of the diagnosis in this study population Correct = correctly classified cases of total study population Sens = sensitivity Spec = specificity PPV = positive predictive value (adjusted for a priori probability) NPV = negative predictive value (adjusted for a priori probability)
The prospective multi-center trial was done in five centers in Asia in Summer and Fall 2004. A total of 222 patients scheduled for coronary angiography were enrolled. patients had to be excluded because of poor ECG tracings (= 1.6%). Angiograms were classified immediately by the respective angiographer and independently by a second interventional cardiologist within 4 weeks after the angiogram. If the two investigators did not agree on the results, they discussed the angiograms until agreement was reached. Coronary stenosis in the angiogram was classified as hemodynamically relevant, if a stenosis of > 70% in at least one vessel or a stenosis of > 50% in the left main coronary artery was detected. After enrollment of 30 patients in center E legal issues were claimed by the center that would not allow a second, independent reading of the angiogram. This led to the exclusion of all 30 patients from center E. MCG tests were done shortly (typically less than 2 hours) before the angiography. The continuous MCG severity score was calculated as part of the MCG analysis. It has a theoretical range from 0 to 20, where higher values relate to a higher probability of myocardial ischemia from coronary disease. A score of 4 or higher is considered indicative of hemodynamically relevant coronary stenosis. A detailed analysis is submitted to Congestive Heart Failure
This table shows the results for MCG (severity score cut-off 4.0) compared to angiography for the detection of hemodynamically relevant coronary stenosis. High sensitivity and specificity as well as predictive values in the entire population and in all subgroups. n = number of patients TP = true positive TN = true negative FP = false positive FN = false negative a priori = incidence of coronary stenosis (as identified in angiography) = a priori probability of the diagnosis in this study population Correct = correctly classified cases of total study population Sens = sensitivity Spec = specificity PPV = positive predictive value (adjusted for a priori probability) NPV = negative predictive value (adjusted for a priori probability)
Boxplots of MCG severity scores in all patients with and without relevant coronary stenosis. Boxes show first to third quartile. Line within box indicates median. Whiskers show high/low. Circles denote outliers, asterisks denote extremes. Numbers near circles and asterisks represent specific patient identifiers.
ROC For The Entire Study Population Using A Cut-Off MCG Score Of 4.0. Area Under The Curve Was 0.881 (0.860 – 0.903)
Boxplots of MCG severity scores in patients with and without relevant coronary stenosis from the individual centers included in the meta-analysis. Boxes show first to third quartile. Line within box indicates median. Whiskers show high/low. Circles denote outliers, asterisks denote extremes. Numbers near circles and asterisks represent specific patient identifiers.
