Risk Stratification After Myocardial Infarction
Risk Stratification After Myocardial Infarction
The invasive nature of PVS certainly limits its application. However, in contrast to many non-invasive risk stratifiers, PVS can be performed in the presence of atrial fibrillation, bundle branch block, or frequent ventricular ectopy. It is probably the most effective stratification technique for identification of post-MI patients at high risk for development of monomorphic VT, but the sensitivity is inadequate to predict SCD. This is particularly true for patients with LVEF < 30%. In these patients, incomplete revascularization, progressive heart failure, and time-dependent modulations of the arrhythmic substrate, factors not adequately addressed by PVS, seem to have a significant relevance. On the other hand, the ability of the technique to reliably induce monomorphic VT offers new options for risk stratification in the era of VT ablation: non-inducibility of VT seems to be a good predictor for freedom from arrhythmia recurrence. Prospective studies with hard endpoints are necessary to evaluate such potential future indications. An example of invasive substrate analysis is depicted in Figure 3.
(Enlarge Image)
Figure 3.
Substrate analysis in a patient with a remote anterior myocardial infarction, a large aneurysm of the left ventricle, and ventricular tachycardia. (A) The 12-lead ECG of the tachycardia with a speed of 100 mm/s. (B) The left ventricular aneurysm as depicted with left ventriculography. In this case, the novel MediGuide™ Technology (St Jude Medical Inc., St Paul, MN, USA) for catheter navigation on pre-recorded cine loops was applied. (C) Voltage mapping of the left ventricle in the Electrophysiology Laboratory with the use of the Ensite NavX™ system (St Jude Medical Inc.). In the reconstructed three-dimensional model of the left ventricle, the grey colour depicts scar, the purple depicts healthy myocardium, and the colours in-between depict diseased myocardium based on the voltage of the local electrograms at the different points of the left ventricle.
Critical Appraisal of Invasive Risk Stratification
The invasive nature of PVS certainly limits its application. However, in contrast to many non-invasive risk stratifiers, PVS can be performed in the presence of atrial fibrillation, bundle branch block, or frequent ventricular ectopy. It is probably the most effective stratification technique for identification of post-MI patients at high risk for development of monomorphic VT, but the sensitivity is inadequate to predict SCD. This is particularly true for patients with LVEF < 30%. In these patients, incomplete revascularization, progressive heart failure, and time-dependent modulations of the arrhythmic substrate, factors not adequately addressed by PVS, seem to have a significant relevance. On the other hand, the ability of the technique to reliably induce monomorphic VT offers new options for risk stratification in the era of VT ablation: non-inducibility of VT seems to be a good predictor for freedom from arrhythmia recurrence. Prospective studies with hard endpoints are necessary to evaluate such potential future indications. An example of invasive substrate analysis is depicted in Figure 3.
(Enlarge Image)
Figure 3.
Substrate analysis in a patient with a remote anterior myocardial infarction, a large aneurysm of the left ventricle, and ventricular tachycardia. (A) The 12-lead ECG of the tachycardia with a speed of 100 mm/s. (B) The left ventricular aneurysm as depicted with left ventriculography. In this case, the novel MediGuide™ Technology (St Jude Medical Inc., St Paul, MN, USA) for catheter navigation on pre-recorded cine loops was applied. (C) Voltage mapping of the left ventricle in the Electrophysiology Laboratory with the use of the Ensite NavX™ system (St Jude Medical Inc.). In the reconstructed three-dimensional model of the left ventricle, the grey colour depicts scar, the purple depicts healthy myocardium, and the colours in-between depict diseased myocardium based on the voltage of the local electrograms at the different points of the left ventricle.
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