Case 1: 52-year-old hypertensive and asymptomatic male patient. Previous ergometry conducted one year ago was positive, investigated with coronary angiotomography with no lesions and with a calcium score of equal to zero. Myocardial perfusion scintigraphy with physical stress (ergometry) was requested for a preoperative evaluation of noncardiac surgery (Figure 1a).

Note the presence of ST depression in the inferior wall (Figure 1b), a site of great sensitivity to alterations in the ergometric test.¹⁴ After, the ST depression evolves to the lateral wall (Figure 1c) when the aVR elevation occurs (Figure 1c).

The ECGs show that aVR elevation gradually disappears as the inferior wall (DII, DIII, and aVF) decreases, proportionally, as if in a mirror (Figure 1d).

This patient reported no chest pain during the test, and 99mTc-MIBI was injected at peak exertion (11 minutes).

Despite the electrocardiographic changes, the patient performed 11 METS, with no chest pain. The ST segment changes occurred with a high load and regressed rapidly during recovery. This information, despite the elevation in aVR, suggests the probability of a false positive, which, according to the exam, may suggest myocardial ischemia.¹⁸

The scintigraphy image shows normal perfusion at rest and after physical stress (Figure 1e).

The patient's resting and stress scintigraphy showing normal perfusion (which suggests ischemia) and no transient dilation of the left ventricular cavity or drop in the ejection fraction induced by stress. Since this patient had already presented an altered ergometry from a year ago, investigated using coronary angiotomography and showing no lesions, it was not necessary to repeat the anatomical exam.

Case 2: Hypertensive, asymptomatic, male patient with dyslipidemia and a history of myocardial revascularization, who had undergone surgery five years prior and had a history of infarction six years ago. Myocardial perfusion scintigraphy was requested to assess physical activity (Figure 2a).

The analysis of the physical stress ECG shows, in the second minute of recovery, an increase in ST depression with a consequent increase in aVR elevation (Figure 2b). The alteration in the ST segment in V1 (Figure 2c and 2b) also reinforces an alteration suggestive of ischemia (Figure 2d).⁸

In Figure 2e, an area of infarction/fibrosis can be seen in the septal wall (bottom line), which could explain the elevation in V1 (Figure 2c). In addition, an image, suggestive of ischemia in the lateral and inferior walls (area of the right and circumflex coronary arteries), was observed. In this example, we have a critically ill patient with ischemia in more than one topography.

After receiving the results of the myocardial perfusion scintigraphy, a coronary angiography was requested, which showed a mammary artery to the patent anterior descending coronary artery; a severe lesion in the occluded saphenous vein graft; in addition to severe lesions in the native bed and in the saphenous bridge to the right coronary artery.

Two positive tests were then observed in asymptomatic patients.

Although there was aVR elevation in both cases, the second represents a greater probability of ischemia according to the perfusion scintigraphy exam, in the stress phase, for the following reasons:

Case 3: 70-year-old, hypertensive, diabetic male patient, who reported episodes of chest pain unrelated to exertion. A myocardial perfusion scintigraphy with physical exertion was requested to evaluate the symptoms.

Figure 3a shows the ECG at rest. In Figure 3b, after 6 minutes of exertion on the treadmill, ST-segment depression was noted in the inferior wall, as well as ST-segment elevation in aVR and V1 (Figure 3c). In Figure 3d, an increase in electrocardiographic changes is evident, even with a lower heart rate (8 minutes of recovery); the ST-segment elevation and aVR appear to progress proportionally to the depression in the other leads.

Figure 3e shows the myocardial perfusion of case 3, showing ischemia in the region of the anterior descending coronary artery. After this change, a coronary angiography was requested, which showed a lesion in the left anterior descending coronary artery. The patient was referred for angioplasty.

In general, when heart rate and blood pressure return to baseline, the ST segment returns to normal and the test can be ended.¹⁹ Cases in which changes intensify during late recovery (Figure 3d) are considered more serious.²⁰ Therefore, when analyzing an exercise test, the moment at which the ECG changes is as important as, if not more important than, the type of change. This assessment helps to differentiate true cases from false positives.

In case 2, extensive ischemia was observed, predominantly in the region of the right and circumflex coronary arteries. In case 3, ischemia was observed in the region of the anterior descending coronary artery. This emphasizes that the exercise test does not locate the lesions, but rather indicates the degree of severity.