The independent prognostic value of left ventricular dyssynchrony

Excerpt

Stress Gated SPECT myocardial perfusion imaging (MPI) provides powerful prognostic information that is incremental to myocardial perfusion pattern including left ventricular ejection fraction (LVEF), transient ischemic dilation, exercise-specific parameters (functional capacity, heart rate response and recovery and electrocardiographic changes), vasodilator-specific parameters (inability to exercise, heart rate response and electrocardiographic changes), and absolute quantitation of myocardial blood flow.1,2 MPI, using phase analysis, can also assess the synchrony of LV contraction. The development of this technique, its validation, and the advantages it provides to the field has been reviewed elsewhere.3,4 Although phase analysis has been used primarily to guide resynchronization therapy, there has been recent interest in the prognostic information provided by its parameters. This has been fueled by the realization that LV mechanical dyssynchrony is common even in patients with narrow QRS on electrocardiography and in those with normal or only mildly depressed LVEF.5-7 Studies have shown that dyssynchrony on phase analysis is associated with worse outcomes in patients with heart failure and in those with end-stage renal disease.7-11 …