Therapies that target scar formation after myocardial infarction (MI) could prevent ensuing heart failure or death from ventricular arrhythmias. We have previously shown that recombinant human platelet-derived growth factor-AB (rhPDGF-AB) improves cardiac function in a rodent model of MI. To progress clinical translation, we evaluated rhPDGF-AB treatment in a clinically relevant porcine model of myocardial ischemia-reperfusion. Thirty-six pigs were randomized to sham procedure or balloon occlusion of the proximal left anterior descending coronary artery with 7-day intravenous infusion of rhPDGF-AB or vehicle. One month after MI, rhPDGF-AB improved survival by 40% compared with vehicle, and cardiac magnetic resonance imaging showed left ventricular (LV) ejection fraction improved by 11.5%, driven by reduced LV end-systolic volumes. Pressure volume loop analyses revealed improved myocardial contractility and energetics after rhPDGF-AB treatment with minimal effect on ventricular compliance. rhPDGF-AB enhanced angiogenesis and increased scar anisotropy (high fiber alignment) without affecting overall scar size or stiffness. rhPDGF-AB reduced inducible ventricular tachycardia by decreasing heterogeneity of the ventricular scar that provides a substrate for reentrant circuits. In summary, we demonstrated that rhPDGF-AB promotes post-MI cardiac wound repair by altering the mechanics of the infarct scar, resulting in robust cardiac functional improvement, decreased ventricular arrhythmias, and improved survival. Our findings suggest a strong translational potential for rhPDGF-AB as an adjunct to current MI treatment and possibly to modulate scar in other organs.

BIA of the IVS is highly effective at creating a transmural ablation line, requiring less ablation and creating longer lesions than SUA. BIA ablation may have a role for post infarct VT involving the IVS.

Intramyocardial adiposity, in association with myocardial discontinuity within left ventricular scar borders, is a significant factor associated with altered electrophysiological properties, aberrant connexin43 expression, and increased propensity for VT after MI.

Background— Sudden arrhythmic death after myocardial infarction (MI) is most frequent in the first month. Early programmed ventricular stimulation (within 1 week) post-MI has been able to identify long-term ventricular tachycardia (VT) occurrence. We aimed to determine the timing of development and stabilization of VT circuits after MI and how the evolution of the underlying substrate differs with VT inducibility. Methods and Results— MIs were induced in 36 sheep. The 21 survivors underwent serial electroanatomic mapping and programmed ventricular stimulation. Animals were classified as VT pos (inducible VT) or VT neg (noninducible VT) at day 8. Forty-three percent of MI survivors were VT pos on day 8 (9/21), and all remained inducible on day 100 with 1.5 (1.0–2.0) and 1.0 (1.0–2.0) morphologies per animal on days 8 and 100, respectively. Twelve-lead electrocardiogram matched in 15 of 19 VTs between days 8 and 100. The earliest presystolic ventricular activations during VT circuits were in similar locations at the 2 time points. The 12 VT neg animals remained noninducible on day 100. There was no difference in voltage or velocity substrate with time or inducibility. The area with fractionated signals increased with time and VT inducibility. VT pos animals had more linear regions of slowed conduction forming conducting channels. Conclusions— The inducibility and earliest presystolic endocardial activation sites of VT as well as voltage and velocity substrate on day 8 predicted those on day 100 postinfarct, indicating early formation and stabilization of the arrhythmogenic substrate. VT inducibility was influenced by the distribution of conducting channels and increased complex fractionated signals.

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