Late Potentials in a Porcine Model of Anterior Wall Myocardial Infarction and Their Relation to Inducible Ventricular Tachycardia

In this study, normal values for signal averaged electrocardiographic parameters were assessed in healthy pigs (n = 100) and the development of late potentials after myocardial infarction (n - 41) in relation to inducible ventricular tachycardia was investigated. Normal values are: filtered QHS duration (QRS) ± 78 msec; root mean square voltage of the averaged QRS complex (V_tot) ± 51 μV, and duration of terminal activity below 30 μV (D₃₀) ± 37 msec. The distribution of the root mean square voitage in the last 30 msec (V₃₀) was biphasic. Two weeks after myocardial infarction, QRS was prolonged from 55 ± 10 to 66 ± 19 msec (P < 0.002), D₃₀ was prolonged from 19 ± 6 msec to 28 ± 13 (P < 0.002). V₃₀ was decreased from 107 ± 135 μV to 45 ± 77 (P < 0.02). The total voltage (V_tot) was decreased from 195 ± 78 to 123 ± 61 μV (P < 0.002). In four pigs (19%) late potentials developed. Sustained ventricular tachycardia was inducible in 11 pigs (52%), ventricular fibrillation in two pigs (10%) and eight pigs (38%) were noninducible. Three of 11 inducible pigs and one of the noninducible pigs had a late potential. The incidence of late potentials and their relation to inducibie sustained ventricular tachycardia is comparable to the situation in man. Therefore, this pig model is an attractive alternative to the commonly used dog models.