Obtaining a right-chest electrocardiogram is essential for diagnosing concomitant right ventricular infarction in patients with inferior wall acute myocardial infarctions. A software program to synthesize right-chest electrocardiographic waveforms from 12-lead electrocardiographic waveforms is available in Japan. However, its reliability has not been fully investigated. Accordingly, the aim of this study was to examine the reliability of ST-segment shifts in the synthesized V 3 R to V 5 R leads. ST-segment shifts in actual and synthesized V 3 R to V 5 R leads were compared during the last 10 seconds of 131 balloon inflations while performing elective percutaneous coronary intervention in 56 patients with coronary artery disease. ST-segment shifts in the actual and synthesized V 3 R, V 4 R, and V 5 R leads were correlated (r = 0.96, p <0.001, r = 0.94, p <0.001, and r = 0.91, p <0.001, respectively). A Bland-Altman analysis showed that the bias between ST-segment shifts in the actual and synthesized V 3 R to V 5 R leads was −3.1, −5.4, and −4.2 μV, respectively, while the limits of agreement between the ST-segment shifts in the actual and synthesized V 3 R to V 5 R leads were −59.2 to 52.9, −61.9 to 51.1, and −59.7 to 51.3 μV, respectively. The κ coefficients for ST-segment elevation of ≥50 and ≥100 μV in the actual and synthesized V 3 R, V 4 R, and V 5 R leads were 0.83 and 0.81, 0.66 and 0.83, and 0.57 and 0.80, respectively. In conclusion, these results indicate that ST-segment shifts in the synthesized V 3 R to V 5 R leads have acceptable reliability, suggesting that synthesized right-chest electrocardiography can be used to diagnose concomitant right ventricular infarction in patients with inferior wall acute myocardial infarctions.
Highlights
•ST-segment shifts were compared in actual and synthesized V 3 R to V 5 R leads during elective PCI.
•ST-segment shifts in actual and synthesized V 3 R to V 5 R leads were highly correlated.
•A Bland-Altman analysis showed acceptable agreement between ST-segment shifts in actual and synthesized V 3 R to V 5 R leads.
•Synthesized right-chest electrocardiography can be used to diagnose right ventricular infarction.
Right ventricular infarction is observed in up to 50% of cases of inferior wall acute myocardial infarction (AMI) and is associated with increased in-hospital mortality and morbidity. Therefore, obtaining a prompt diagnosis of concomitant right ventricular infarction in patients with inferior wall AMIs is clinically important. The right-chest electrocardiogram (ECG) is essential for diagnosing concomitant right ventricular infarction in patients with inferior wall AMIs. A software program to synthesize right-chest V 3 R to V 5 R electrocardiographic waveforms from 12-lead waveforms is available in Japan. However, its reliability has not been fully validated. In this study, we examined the reliability of ST-segment shifts in the synthesized V 3 R to V 5 R leads in patients who underwent elective percutaneous coronary intervention (PCI).
Methods
A total of 56 patients (39 men and 17 women, mean age 72.1 ± 10.0 years) with coronary artery disease who were planning to undergo elective PCI for significant stenosis in the native coronary artery at Koseiren Tsurumi Hospital from January 2013 and September 2013 were prospectively enrolled in this study. The exclusion criteria included emergent PCI for acute coronary syndromes, PCI for a totally or subtotally occluded coronary artery (Thrombolysis In Myocardial Infarction [TIMI] grade 0 to 2 flow) or left main trunk disease, severe congestive heart failure (New York Heart Association functional class IV), and atrial fibrillation or flutter. The study protocol was approved by the Ethics Committee of Oita University Hospital, and informed consent was obtained from all patients.
Elective PCI, including balloon coronary angioplasty and coronary stenting, was performed using a radial or femoral approach. Each episode of balloon inflation was performed for 60 seconds. Standard 12-lead ECGs together with V 3 R to V 5 R ECGs were recorded with an ECG-1550 electrocardiograph (Nihon Kohden Corporation, Tokyo, Japan) immediately before PCI and during the last 10 seconds of each 60-second balloon inflation. All digital data for the 12-lead electrocardiographic signals were instantaneously processed at a sampling rate of 500 Hz. Synthesized V 3 R to V 5 R electrocardiographic waveforms were then created with a computer software program (Nihon Kohden Corporation) that can synthesize V 3 R to V 5 R electrocardiographic waveforms from 12-lead waveforms as follows. The vector of the electric potential from the heart was obtained from the 12-lead ECG, and a transfer coefficient matrix, which represented an average model of volume conductors among 147 Japanese subjects (98 men and 49 women, mean age 60.6 ± 16.1 years), was derived mathematically from data for the 12-lead and V 3 R to V 5 R ECGs. By estimating the fixed conductance around the heart, the synthesized V 3 R to V 5 R ECG was obtained from the 12-lead ECG. The magnitude of the ST-segment shifts at the J point relative to the beginning of the P wave during the last 10 seconds of each 60-second balloon inflation was automatically calculated with a software program (ECAPS12C; Nihon Kohden Corporation).
Hypertension was defined as systolic blood pressure ≥140 mm Hg, diastolic blood pressure ≥90 mm Hg or treatment with antihypertensive medications. Dyslipidemia was defined as a serum low-density lipoprotein cholesterol level ≥140 mg/dl, a high-density lipoprotein cholesterol level <40 mg/dl, a triglyceride level ≥150 mg/dl, or treatment with lipid-lowering drugs. Diabetes mellitus was defined as a fasting plasma glucose level ≥126 mg/dl, a plasma glucose level ≥200 mg/dl at 2 hours after a 75-g glucose load, or treatment with hypoglycemic agents.
Continuous data are expressed as mean ± SD. ST-segment shifts in the actual and synthesized V 3 R to V 5 R leads were compared using paired Student’s t tests. Pearson’s correlation coefficients were calculated to determine the correlations between the ST-segment shifts in the actual and synthesized V 3 R to V 5 R leads. The agreement between the ST-segment shifts in the actual and synthesized V 3 R to V 5 R leads was assessed using a Bland-Altman analysis. The agreement for ST-segment elevation of ≥50 and ≥100 μV in the actual and synthesized V 3 R to V 5 R leads was evaluated using κ coefficients, which were interpreted as follows: ≤0.20 = poor agreement, 0.21 to 0.40 = fair agreement, 0.41 to 0.60 = moderate agreement, 0.61 to 0.80 = good agreement, and 0.81 to 1.0 = excellent agreement. The statistical analyses were performed with SPSS Statistics 20 (IBM, Armonk, New York).
Results
The patient characteristics are listed in Table 1 . We analyzed the ST-segment shifts in the actual and synthesized V 3 R to V 5 R leads during 131 balloon inflations when performing PCI for 42 lesions in the left anterior descending coronary artery, 37 lesions in the left circumflex artery, and 52 lesions in the right coronary artery. The mean number of leads (except for lead aVR and leads V 3 R to V 5 R) with ST-segment elevation ≥100 μV during the 131 balloon inflations was 2.2 ± 1.7.
| Age (years) | 72.1 ± 10.0 |
| Male | 39 (70%) |
| Body mass index (kg/m 2 ) | 22.9 ± 3.1 |
| Hypertension | 49 (88%) |
| Dyslipidemia | 36 (64%) |
| Diabetes mellitus | 19 (34%) |
| Smoker | 30 (54%) |
| Prior myocardial infarction | 35 (63%) |
| Multivessel coronary disease | 35 (63%) |
| Medications | |
| Calcium antagonists | 27 (48%) |
| Beta-blockers | 20 (36%) |
| Nitrates | 36 (64%) |
Figure 1 shows actual and synthesized V 3 R to V 5 R ECGs during a balloon occlusion. The ST-segment shifts were slightly but significantly lower in the synthesized V 4 R lead than in the actual V 4 R lead (21.2 ± 46.0 vs 26.6 ± 66.4 μV, p = 0.03) and tended to be lower in the synthesized V 5 R lead than in the actual V 5 R lead (16.2 ± 38.3 vs 20.4 ± 57.8 μV, p = 0.09). The ST-segment shifts in the synthesized and actual V 3 R leads did not differ significantly (29.2 ± 63.3 vs 32.3 ± 81.4 μV, p = 0.20). The ST-segment shifts in the actual and synthesized V 3 R to V 5 R leads were highly correlated ( Figure 2 ).
The Bland-Altman analysis showed that the bias (mean difference between the ST-segment shifts in the actual and synthesized V 3 R to V 5 R leads) was −3.1, −5.4, and −4.2 μV, respectively, while the limits of agreement between the ST-segment shifts in the actual and synthesized V 3 R to V 5 R leads were −59.2 to 52.9, −61.9 to 51.1, and −59.7 to 51.3 μV, respectively ( Figure 3 ).
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