Perspective of preexcitation induced cardiomyopathy; early septal contraction, and subsequent rebound stretch.

BACKGROUND:Preexcitation-induced cardiomyopathy (PIC) is defined as a disease presenting ventricular dyssynchrony because of preexcitation through an accessory pathway (AP), being a cousin of pacing-induced cardiomyopathy. The present review aims at providing perspective of this uncharted subgroup. METHODS:In order to determine mechanisms and clinical characteristics of PIC, 63 patients in 29 literature reports were reviewed. RESULTS:A median age at onset was 4 (0.1-59) years; 55 patients (87%) under 18 years old including 16 infants. Twenty patients (32%) experienced supraventricular tachycardia prior and subsequent to the PIC onset. Heart failure and left ventricular (LV) dysfunction did not correlate with other clinical features. All the 65 APs identified (duplicated in 2 patients) were located on the right side of the atrioventricular junction; at the septal area (in 55%) or the anterolateral aspect (in 22%). AP conduction was successfully eliminated by medical or interventional treatments where attempted. LV function returned to normal within 6 months in 67% of patients, while recovery took longer than 3 years in 8%. Frequently seen at the basal segments of the interventricular septum were early contraction within the QRS complex, dyskinesis at mid-systole, and aneurysm/bulging or local thinning. CONCLUSIONS:Several characteristic factors became clear as described above. Rebound stretch following early shortening of the interventricular septum is seemingly the major mechanism of PIC, and thus a right septal or right anterior/anterolateral AP needs attention as a higher risk for PIC.