Thoracic location of the lead with maximal ST-segment deviation during posterior and right ventricular ischemia: comparison of 18-lead ECG with 192 estimated body surface leads

High-Resolution Body Surface Potential Mapping in Exercise Assessment of Ischemic Heart Disease

Standard 12-lead ECG exercise testing is commonly used for screening of ischemic heart disease (IHD). We studied if high-resolution body surface potential mapping (HR-BSPM) during exercise offers advantages over current standards in noninvasive evaluation of IHD. This study was carried out on 90 IHD patients and 33 healthy controls. The 67-lead HR-BSPM was recorded at rest and during exercise. Twenty-one ECG parameters including classical ST criteria were compared. The effectiveness of methods was verified based on the results of SPECT and coronary angiography. The most effective parameters in the diagnosis of IHD were: amplitude parameter ΔST60 and δT parameter showing T-wave morphology changes during exercise. The sensitivities/specificities of ΔST60 and δT parameters for the HR-BSPM were 70/69 and 59/62%, while for the standard 12-lead ECG system they were: 63/62 and 59/56%. These results demonstrate the usefulness of HR-BSPM measurements during exercise. HR-BSPM resulted in higher sensitivities and specificities compared to the standard 12-lead exercise test. The advantage was partially associated with observed ischemic changes outside standard precordial leads position that were not visible when using the standard 12-lead exercise test. This justifies research into the optimization of the number and position of ECG leads in exercise testing.

ECG Techniques and Technologies

The electrocardiogram (ECG) continues to be a critical component of the evaluation of patients who have signs and symptoms of emergency cardiac conditions. This tool is now approximately 100 years old and has been a standard in clinical practice for more than half a century. Application of new signal processing techniques and an expansion in the use of additional leads allows clinicians to extract more and more information from the cardiac electrical activity. An understanding of the technology inherent in the recording of ECGs allows one to more fully understand the benefits and limitation of electrocardiography.

Body surface potential mapping improves detection of ST segment alteration during percutaneous coronary intervention

BACKGROUND

The 12-lead electrocardiogram underestimates ST segment alteration in acute coronary syndromes compared with multi-lead body surface mapping. We assessed whether 80-lead mapping would improve detection of ST alteration during percutaneous coronary intervention.

METHODS

Simultaneous maps and 12-lead electrocardiograms were recorded pre-procedure, during balloon inflation and post-procedure from patients undergoing elective intervention to native coronary arteries. Recordings were obtained from 39 inflations (19 patients). All arteries were successfully stented.

RESULTS

Mean 'lead specific' ST alteration (the difference in ST elevation/depression between pre-procedure and inflation recordings in the lead showing maximal ST alteration) was greater on the map than on electrocardiogram, both for ST elevation (0.16+/-0.02 vs. 0.06+/-0.01 mV; p<0.001) and ST depression (0.11+/-0.017 vs. -0.03+/-0.006 mV; p<0.001). During first inflations (n=19), mean lead specific ST elevation and depression on map were greater than on electrocardiogram (0.20+/-0.034 vs. 0.07+/-0.015 mV; p<0.001 and 0.11+/-0.029 vs. 0.03+/-0.009 mV; p=0.001, respectively). Mapping detected greater summated ST elevation and depression during inflation than electrocardiogram (0.04+/-0.005 vs. 0.021+/-0.003 mV; p<0.001 and 0.026+/-0.004 vs. 0.011+/-0.002 mV; p<0.001, respectively). Qualitative analysis of maps and electrocardiograms showed that 21/39 (53.8%) maps recorded during inflation met criteria for myocardial ischaemia compared with 7/39 (17.9%) electrocardiograms (p<0.001).

CONCLUSION

Body surface mapping compared with the 12-lead electrocardiogram improves detection of myocardial ischaemia during intervention.

Posterior myocardial infarction with isolated ST elevations in V8 and V9: Is this an "ST elevation MI"?

We report a case of a 53-year-old man whose first manifestation of coronary artery disease was an acute isolated posterior myocardial infarction (IPMI). Acute IPMI is relatively uncommon and predominantly due to occlusion of the left circumflex coronary artery. IPMI is challenging to diagnose due to the absence of ST segment elevation on a standard 12-lead electrocardiogram (ECG) even in the setting of total coronary artery occlusion and transmural (Q-wave) infarct. We discuss the diagnostic implications of the absence of tall R waves in leads V1 and V2 on this patient's ECG. The utility of posterior leads (V7 through V9) is demonstrated. The controversy surrounding the use of thrombolytic therapy or primary angioplasty in the setting of acute IPMI without ST segment elevation on a standard 12-lead ECG is reviewed.