Nomograms for estimating coronary artery disease prognosis with gated stress myocardial perfusion SPECT.

BACKGROUND

Nomograms can be useful tools for estimating coronary artery disease (CAD) risk. We sought to devise risk-based nomograms for stress myocardial perfusion SPECT to include measures of % ischemic myocardium and left ventricular function.

METHODS

A total of 4,575 patients were consecutively and prospectively enrolled in the Myoview Prognosis Registry. Multivariable Cox proportional hazards model were employed to estimate CAD death or MI. Nomograms were devised from the results of the Cox models.

RESULTS

CAD death or MI rates worsened in a gradient manner by the % ischemic myocardium. Higher risk patients were those with a rest and/or post-stress LVEF ≤ 45%. A nomogram was developed to estimate 2-year CAD death or MI-free survival for exercising and pharmacologic stress patients by their post-stress LVEF and % ischemic myocardium MPS results. Patients undergoing pharmacologic stress with a rest and/or post-stress LVEF ≤ 45% with high risk ischemic findings had the lowest CAD death or MI event-free survival. For exercising patients with a preserved resting LVEF > 45%, 2-year CAD death or MI event-free survival ranged from 99.4% to 89% for 0% to ≥20% ischemic myocardium. Those at highest risk included patients undergoing pharmacologic stress with depressed LVEF. For pharmacologic stress patients with a resting LVEF ≤45%, 2-year CAD death or MI event-free survival ranged from 89% to 48% for 0% to ≥20% ischemic myocardium. For pharmacologic stress patients with a post-stress LVEF ≤ 45%, 2-year CAD death or MI event-free survival ranged from 88% to 46% for 0% to ≥20% ischemic myocardium. A validation cohort revealed moderate-strong correlation between observed and predicted survival (r = 0.71). Average discordance between observed and predicted survival was ≤2% but was greater for higher risk patients with lower predicted survival estimates.

CONCLUSIONS

Risk-based nomograms estimating important CAD outcomes may serve as a clinically useful tool to target therapeutic intervention for high risk patient subsets.