Subepicardial injury pattern

Figure 8.10 Patient with crises of Prinzmetal angina, who presented during these crises typical of subepicardial injury pattern. During the remission of pain (Holter method recording) the injury pattern disappeared within a few seconds.

On the contrary, in Q-wave infarction the coronary artery occlusion is usually complete, and classically it was considered that the MI was transmural and often presents homogeneous wall involvement (QS pattern) or at least the infarction involves the subendocardium and also part of the subepicardium in contact with the subendocardium (QR pattern) (Figure 5.2C). CMR has demonstrated that often Q-wave Mis are not trans-mural and, on the contrary, often are transmural non-Q-wave Mis (Moon et al., 2004). The Q-wave MI often appear in a patient without very much prior ischaemia (first infarction). Consequently, an acute ischaemia (ACS) generates a poor-quality TAP in the entire wall that is recorded, from the precordium, as subepicardial injury pattern (ST-segment elevation) (Figures 4.5 and 4.8). Later, the myocardium becomes non-excitable and Q wave of necrosis develops (Figures 5.2B and 5.3). 

Figure 3.4 Electrocardiographic - pathological correlations after the occlusion of a coronary artery in an experimental animal with its thorax closed. It changes from a subendocardial ischemia pattern (tall and peaked T wave) to a pattern of a subepicardial injury, transmural in clinical practice, (ST segment elevation) when the acute clinical ischemia is more severe. Finally, the "q wave of...

Figure 3.9 In case that in basal state a certain degree of ischaemia with subendocardial predominance exists too mild to produce clear ECG changes, an increase of active ischaemia still with subendocardial predominance will produce an ST-segment depression (subendocardial injury pattern) (A). If as a consequence of ischaemia there is a delay in repolarisation predominating in subepicardium or being transmural, a flattened or negative T wave appears in leads with, but also without, predominant R wave (B-1) (subepicardial ischaemia pattern). The latter pattern is...

Electrocardiographic pattern of subepicardial injury in patients with narrow QRS diagnosis and differential diagnosis... 

The ECG pattern of ST-segment elevation (subepicardial injury) is found in IHD, but also in other situations as well. In the second part we will comment that the presence of clinical signs of ischaemia (precordial pain, etc.) and the presence of ST-segment elevation of the characteristics explained here (typical and atypical patterns - see Table 8.1) constitute the clinical syndrome known as ACS with ST-segment elevation (STE-ACS), which has different clinical and ECG characteristics (Tables 8.1 and 8.2) than ACS without ST-segment elevation (NSTE-ACS). However, in both clinical syndromes (STE-ACS and NSTE-ACS), there are... 

When the subepicardial injury occurs in the inferior and lateral wall (LCX or RCA occlusion), the direct pattern of the ST-segment elevation is seen in inferior leads and in the leads recorded in the back (posterior thoracic leads). In these cases, often an ST-segment depression is recorded in V1-V3 leads, as a mirror pattern of ST-segment elevation recorded in the back (Figure 4.15). 

ECG pattern of subendocardial ischaemia and the pattern of subepicardial ischaemia. Slight ST-segment elevation may be noted in V1 lead. (B) Few hours later appeared typical pattern of subepicardial injury (ST-segment elevation) with QS of necrosis in V2-V4. 

If the delay is subepicardial or even transmural (see The concept of ECG patterns of ischaemia, injury and necrosis ) (p. 20). this delay of repolarisation without change of shape of TAP generates a flattened or negative T wave. 

Figure 4.5 How the respective patterns of subendocardial (B) and subepicardial (C) injuries are generated according to the theory that the normal ECG pattern (A) is the result of the sum of subendocardial and subepicardial PATs.

In first part we have discussed the criteria for diagnosis and location of ST-segment elevation (pattern of subepicardium injury) and ST-segment depression or negative T wave (pattern of subendocardial injury and subepicardial ischaemia). Now we will discuss the clinical evolution, prognostic implications and risk stratification of these patterns. 

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