Author + information
- Scott D. Lick, MD, FACC⁎ ()
- ↵⁎Department of Surgery, University of Texas Medical Branch, Route 0528, 301 University Boulevard, Galveston, TX 77555
In a recent study in JACCby the RESTORE Investigators, the researchers equate postoperative elevation in left ventricular ejection fraction (LVEF) (29.6% to 39.5%) and decrease in left ventricular end-systolic index (LVESI) (80 ml to 56 ml) to improved LV function. However, an increase in LVEF and a decrease in LVESI are geometric necessities of the operation, which involves a concentric shrinking of the infarcted anterior/septal myocardial area with a purse-string stitch, and closure of the small residual defect with an oval patch. They are predicated within the notion of the ventricular reduction itself, assuming the remaining sarcomeres continue their usual function. To say that ventricular function is improved, one would need data to show that stroke volume or, secondarily, pulmonary artery pressures or cardiac output improved. None of these data were provided; indeed, one would expect stroke volume and cardiac output not to change, and pulmonary artery pressures to fall based on Laplace’s law.
The investigators make a good case in their discussion that they have helped their patients based on historical series involving individual components of the operation in subjects with dilated hearts (coronary artery bypass graft, ventricular aneurysmectomy, mitral repair). But the leap from what is essentially a deductive tautology (A = A) to their empiric finding of improved clinical symptoms requires hemodynamic data for inductive reasoning about cause and effect (1).
- American College of Cardiology Foundation