Inferior infarction, evolution after fibrinolysis

ECG: Sinus rhythm, normal PR interval; presence of Q-wave in the inferior territory with ST-segment elevation and positive T-wave suggestive of an acute inferior myocardial infarction; reciprocal high amplitude depression in leads I, aVL, V2;

ECG 2:

ECG 2: Tracing recorded simultaneously with the right and posterior leads; absence of elevation in these additional leads; inferior infarction without right ventricular extension or to the posterobasal aspect of the left ventricle;

ECG 3:

ECG 3: The hospital center does not have emergency angioplasty services and is 2 hours away from the first available coronary angiography unit; fibrinolysis is thus performed; tracing recorded 15 minutes after the initiation of fibrinolysis; slight decrease in the amplitude of the elevation and of the reciprocal depression;

ECG 4:

ECG 4: Tracing recorded 30 minutes after the initiation of fibrinolysis; resolution of pain and evidence of ventricular couplets (alternans between a ventricular complex of sinus origin and a ventricular extrasystole);

ECG 5:

ECG 5: Tracing recorded at the end of fibrinolysis; complete regression of the elevation with the appearance of a negative T-wave in leads III and aVF;

ECG 6:

ECG 6: Tracing recorded two days after; sinus bradycardia with negative, wide, symmetrical T-waves in the inferior territory with deep Q-waves; negative T-waves from V4 to V6;

Comments: This patient presented with an inferior myocardial infarction requiring fibrinolysis therapy. Secondary coronary angiography revealed a severe stenosis of the second segment of the right coronary artery (absence of thrombus indicating the efficacy of fibrinolysis); this patient received angioplasty with stent placement. Ultrasound showed inferior hypokinesia with a left ventricular ejection fraction evaluated at 55%.

This patient presented various signs of effective reperfusion after fibrinolysis: rapid disappearance of pain and segment elevation, ventricular couplets in conjunction with pain cessation, premature T-wave inversion in the territory previously presenting with elevation.

As a result of the thrombosis of a coronary artery, reperfusion may sometimes be spontaneous or occur as a result of fibrinolysis treatment or emergency angioplasty. In the absence of reperfusion, ST-segment elevation usually regresses within 12 to 24 hours with the appearance and persistence of necrosis Q-waves in the culprit territory. When fibrinolytic treatment is performed, certain clinical and electrocardiographic signs are suggestive of effective reperfusion.

At a time when coronary angiography was not yet available, it was not possible to directly visualize the resumption of flow and the following signs were the only signs allowing to suspect reperfusion:

• An early regression of the amplitude of the elevation (>50% within a few minutes) is a good indicator of a resumption of myocardial perfusion and is most often associated with resolution of the anginal symptomatology and a recovery of segmental myocardial contractility; the rapid regression of the elevation is a factor of good prognosis;
• An early inversion of the T-wave (observed within 2 hours after the initiation of fibrinolysis) in the leads that exhibited the elevation is also a very specific sign of reperfusion;
• Reperfusion arrhythmias are frequent and are most often benign; the appearance of isolated ventricular extrasystoles, in couplets (as in this patient) or in short nonsustained  bursts is frequently observed during reperfusion; an AIVR (accelerated idioventricular rhythm), corresponding to a focal ventricular rhythm (between 60 and 120 bpm), occurs in about 50% of patients with effective reperfusion; these reperfusion arrhythmias are usually transient and only last a few seconds or minutes and do not require any particular treatment;
• In certain patients with inferior or posterior infarction, reperfusion may be accompanied by the occurrence of a transient sinus bradycardia which may temporarily alter the hemodynamics of the patient;
• In contrast, the persistence of pain and of the elevation, the presence of a hemodynamic instability are indicative of an absent or incomplete reperfusion; similarly, the occurrence of sustained monomorphic ventricular tachycardia should not be considered as a sign of reperfusion;

Take-home message: Following fibrinolytic therapy, various clinical and electrocardiographic signs are suggestive of an effective reperfusion: rapid resolution of anginal symptomatology, regression of the elevation, occurrence of reperfusion arrhythmias, early appearance of a negative T-wave.