Relation of left-ventricular dyssynchrony by phase analysis of gated SPECT images and cardiovascular events in patients with implantable cardiac defibrillators

Left-ventricular (LV) dyssynchrony could be measured by gated SPECT myocardial perfusion imaging (MPI). This study examined the relation between the degree of dyssynchrony and outcome in patients with implantable cardiac defibrillators (ICDs). We studied 70 patients with ICD and LV ejection fraction (EF) <.40 by gated MPI (performed within 6 weeks of the device implantation). The images were re-processed using phase analysis to derive phase standard deviation (SD) and histogram bandwidth. All-cause mortality and appropriate ICD shocks were identified as the primary endpoint. There were 87% men, aged 62 +/- A 11 years. The EF was 26 +/- A 8% (range 12%-39%). The phase SD was 51A degrees A A +/- A 20A degrees (range 12A degrees-99A degrees) and the histogram bandwidth was 157A degrees A A +/- A 72A degrees (range 21A degrees-327A degrees). The SD and bandwidth were significantly greater than corresponding values in patients with normal EF (15.8 +/- A 11.8A degrees and 42.0 +/- A 28.4A degrees, respectively, P < .0001, each). At 1 year, 8 patients (11%) died or had shocks. The patients with events had higher phase SD than those without events (60 +/- A 5A degrees vs 50 +/- A 21A degrees, P = .002). The histogram bandwidth was also higher in those with events (185 +/- A 37 vs 154 +/- A 75, P = .07). All patients with event had a phase SD a parts per thousand yen 50A degrees, while none of the patients with a phase SD < 50A degrees (N = 26) had an event (P = .02). The severity of LV dyssynchrony by phase analysis in patients with LV dysfunction, and ICD is associated with increased risk of death and appropriate ICD shock; a phase SD < 50A degrees was associated with no events at 1 year.