Enhanced Infarct Border Zone Function and Altered Mechanical Activation Predict Inducibility of Monomorphic Ventricular Tachycardia in Patients with Ischemic Cardiomyopathy

Abstract

To prospectively determine whether mechanical behavior of left ventricular wall segments that contain different degrees of scar tissue and are located at different distances from the interface between infarcted and noninfarcted myocardial tissue can help predict inducibility of monomorphic ventricular tachycardia (VT) in patients with ischemic cardiomyopathy. This HIPAA-compliant study was institutional review board approved; written informed consent was obtained from all patients. Forty-six patients (36 men, 10 women; mean age +/- standard deviation, 61.6 years +/- 11.9) with prior myocardial infarction (MI) and left ventricular dysfunction were referred for defibrillator implantation and underwent an electrophysiologic examination and tagged contrast-enhanced magnetic resonance (MR) imaging. Peak circumferential shortening strain (Ecc) and time to peak Ecc were measured in 12 segments from short-axis sections. Remote, adjacent, and border zones were defined according to increasing proximity to the MI. Patients in whom monomorphic VT could be induced (ie, inducible patients) were considered positive for inducibility. Relationships between inducibility of monomorphic VT, peak Ecc, and time to peak Ecc were analyzed with one-way analysis of variance and Bonferroni test. Inducible patients had more infarcted and border zone sectors and a shorter time to peak Ecc than did noninducible patients in the border zone and adjacent and infarcted regions (P < .001). Peak Ecc in the border zone of inducible patients (-11.42% +/- 0.46 [standard error]) was greater than that in noninducible patients (-10.18% +/- 0.38; P < .05). Ratio of Ecc in border zone and in remote regions was greater (P < .05) in inducible patients than in noninducible patients (1.31 +/- 0.27 vs 0.64 +/- 0.13, respectively). Enhanced border zone function defined as greater Ecc and earlier time to peak Ecc showed positive correlation to VT inducibility in patients with prior MI and left ventricular dysfunction.