To the Editor—Response

Abstract

Dr. Chirife raises several questions about our publication “Prospective comparison of echocardiographic AV delay optimization methods for cardiac resynchronization therapy” (HR 2006;148:154). The first point raised is that the Ritter method, also known as the mitral inflow method, was devised for patients with complete AV block and DDD pacemakers. 1 Ritter P. Dib J.C. Mahoux V. Lelievre T. Soyeur D. Lavergne T. Cazeau S. Guize L. Rabin L.M. Daubert C. New Method for Determining the Optimal atrio-ventricular delay in patients paced in DDD mode for complete atrio-ventricular block. PACE. 1995; 18: 855 Google Scholar We agree completely. Because the method has been used in large trials of CRT, 2 Abraham W.T. Fisher W.G. Smith A.L. Delurgio D.B. Leon A.R. Loh E. Kocovic D.Z. Packer M. Clavell A.L. Hayes D.L. Ellestad M. Trupp R.J. Underwood J. Pickering F. Truex C. McAtee P. Messenger J. Cardiac resynchronization in chronic heart failure. New England Journal of Medicine. 2002; 346: 1845-1853 Crossref PubMed Scopus (4170) Google Scholar , 3 Young J.B. Abraham W.T. Smith A.L. Leon A.R. Lieberman R. Wilkoff B. Canby R.C. Schroeder J.S. Liem L.B. Hall S. Wheelan K. Combined cardiac resynchronization and implantable cardioversion defibrillation in advanced chronic heart failure the MIRACLE ICD Trial. JAMA. 2003; 289: 2685-2694 Crossref PubMed Scopus (1432) Google Scholar we felt that it was important to test the reliability of the mitral inflow method for CRT patients. As our results demonstrate, the method substantially underperforms the Aortic VTI method. In contrast, the original abstract by Ritter et al. demonstrates concordance between the two methods in patients with complete heart block. The second concern raised is that patients in our study were only tested in an atrial synchronous mode (VDD) rather than in an AV sequential mode. This is the case for all major CRT trials published to date. In an effort to isolate the benefits of CRT from those arising from treatment of chronotropic incompetence, the VDD mode has been preferred in clinical trials of CRT. We agree that AV sequential pacing may be preferred in many clinical situations. Aortic VTI optimization of the AV delay in this mode should still be valid in the DDD mode.