The extent of scar tissue and viable myocardium were directly related to the response to CRT. Furthermore, scar tissue in the LV pacing lead region may prohibit response to CRT. Evaluation for viability and scar tissue may be considered in the selection process for CRT.

Cardiac sympathetic denervation predicts ventricular arrhythmias causing appropriate ICD therapy as well as the composite of appropriate ICD therapy or cardiac death.

Cardiac resynchronization therapy (CRT) is now a well-recognized therapeutic option for patients with end-stage heart failure. However, not all patients respond to CRT, and, therefore, preimplantation identification of responders is desirable. The aim of the present study was to investigate whether the degree of left ventricular (LV) dyssynchrony, as assessed with phase analysis from gated myocardial perfusion SPECT (GMPS), can predict which patients will respond to CRT. Methods: Forty-two patients with severe heart failure, depressed LV ejection fraction, and wide QRS complex were prospectively included for implantation of a CRT device and underwent GMPS and 2-dimensional echocardiography as part of the clinical protocol. Clinical status was evaluated using the New York Heart Association (NYHA) classification, 6-min walk test, and quality-of-life score. The histogram bandwidth and phase SD (parameters indicating LV dyssynchrony) were assessed from GMPS, and the clinical status and echocardiographic variables were reassessed at 6-mo followup. Results: Responders (71%) and nonresponders (29%) had comparable baseline characteristics, except for histogram bandwidth (175°6 63°vs. 117°6 51°[P , 0.01]) and phase SD (56.3°6 19.9°vs. 37°.1 6 14.4°[P , 0.01]), which were significantly larger in responders compared with nonresponders. Moreover, receiver-operating-characteristic curve analysis demonstrated an optimal cutoff value of 135°for histogram bandwidth (sensitivity and specificity of 70%) and of 43°for phase SD (sensitivity and specificity of 74%) for the prediction of response to CRT. Conclusion: Response to CRT is related to the presence of LV dyssynchrony assessed by phase analysis with GMPS. A cutoff value of 135°for histogram bandwidth and of 43°for phase SD could be used to predict response to CRT. Larger prospective studies are warranted to confirm the present findings.Key Words: left ventricular dyssynchrony; cardiac resynchronization therapy; SPECT; heart failure J Nucl Med 2007; 48: 1104 -1111 DOI: 10.2967 In the recent years, cardiac resynchronization therapy (CRT) has emerged as a new treatment strategy for a subgroup of patients with end-stage heart failure, a depressed left ventricular ejection fraction (LVEF), and wide QRS complex on the surface electrocardiogram (.120 ms) (1). Although initial studies reported promising results, approximately 20%-30% of the patients do not respond to CRT (1-4). Recent data have indicated that LV dyssynchrony may be mandatory for response to CRT (5,6). A wide QRS complex may not adequately indicate LV dyssynchrony, as 30% of the patients with a wide QRS complex (.120 ms) do not have substantial LV dyssynchrony on echocardiography whereas, on the other hand, approximately one third of the patients with a narrow QRS appear to have substantial LV dyssynchrony on echocardiography (7,8).At present, various imaging techniques are available for the assessment of LV dyssynchrony, including echocardiography with tissue Doppler imaging (TDI), or strain imaging, and MRI (9,10...

ONE MARROW CELL THERAPY IS currently being investigated as a new therapeutic option for patients with ischemic heart disease. The goal of this treatment is to improve myocardial perfusion and contractile performance through administration of therapeutic cells into ischemically damaged myocardium. The majority of clinical studies conducted so far investigated whether intracoronary bone marrow cell infusion could enhance functional recovery after acute myocardial infarction. 1-3 Animal model studies, however, suggested that bone marrow cell therapy may also improve myocardial perfusion and increase left ventricular (LV) function in chronic ischemia. 4,5 A number of nonrandomized clinical studies indicated the safety and feasibility of intramyocardial bone marrow cell injection. 6-9 Moreover, a beneficial effect on myocardial perfusion and LV function was presumed. Until now, only 2 smallsized randomized controlled studies assessed the effect of bone marrow cell injection in patients with chronic myocardial ischemia. 10,11 Since the results of these 2 studies were discrepant, the beneficial effect of this treatment mo-Author Affiliations are listed at the end of this article.

The significance of left ventricular (LV) dyssynchrony for the prediction of response to cardiac resynchronization therapy (CRT) has been demonstrated. Parameters reflecting LV dyssynchrony (phase SD, histogram bandwidth) can be derived from gated myocardial perfusion SPECT (GMPS) using phase analysis. The feasibility of LV dyssynchrony assessment with phase analysis on GMPS using Quantitative Gated SPECT (QGS) software has not been demonstrated in patients undergoing CRT. The aim of the present study was to validate the QGS algorithm for phase analysis on GMPS in a direct comparison with echocardiography using tissue Doppler imaging (TDI) for LV dyssynchrony assessment. Also, prediction of response to CRT using GMPS and phase analysis was evaluated. Methods: Patients (n 5 40) with severe heart failure (New York Heart Association class III-IV), an LV ejection fraction of no more than 35%, and a QRS complex greater than or equal to 120 ms were evaluated for LV dyssynchrony using GMPS and echocardiography with TDI. At baseline and after 6 mo of CRT, clinical status, LV volumes, and LV ejection fraction were evaluated. Patients with functional improvement were classified as CRT responders. Results: Both histogram bandwidth (r 5 0.69, r 2 5 0.48, SEE 5 25.4, P , 0.01) and phase SD (r 5 0.65, r 2 5 0.42, SEE 5 26.8, P , 0.01) derived from GMPS correlated significantly with TDI for assessment of LV dyssynchrony. At baseline, CRT responders showed a significantly larger histogram bandwidth (94°6 23°vs. 68°6 21°, P , 0.01) and a larger phase SD (26°6 6°vs. 18°6 5°, P , 0.01) than did nonresponders. Receiver-operating-characteristic curve analysis identified an optimal cutoff value of 72.5°for histogram bandwidth to predict CRT response, yielding a sensitivity of 83% and a specificity of 81%. For phase SD, sensitivity and specificity similar to those for histogram bandwidth were obtained at a cutoff value of 19.6°. Conclusion: QGS phase analysis on GMPS correlated significantly with TDI for the assessment of LV dyssynchrony. Moreover, a high accuracy for prediction of response to CRT was obtained using either histogram bandwidth or phase SD.