Prediction of 2-year major adverse cardiac events from myocardial perfusion scintigraphy and clinical risk factors

Abstract

Background: We developed CRAX2MACE, a new tool derived from clinical and SPECT myocardial perfusion imaging (MPI) variables, to predict 2-year probability of major adverse cardiac event (MACE) comprising death, hospitalized acute myocardial infarction or coronary revascularization.

Methods: Consecutive individuals with SPECT MPI 2001-2008 had two-year MACE determined from population-based health services data. CRAX2MACE included age, sex, diabetes, recent cardiac hospitalization, pharmacologic stress, stress total perfusion deficit (TPD), ischemic (stress-rest) TPD, left ventricular ejection fraction and transient ischemic dilation ratio. Two-year event rates were classified as low (< 5%), moderate (5.0-9.9%), high (10-19.9%) and very high (20% or greater).

Results: The study population comprised 3896 individuals for the development and 1946 for the validation subgroups with subsequent MACE in 589 (15.1%) and 272 (14.0%), respectively. CRAX2MACE, derived from the development subgroups, accurately stratified MACE risk in the validation subgroup (area under the receiver operating characteristics curve 0.79) with stepwise increase in the observed event rate with increasing predicted risk category (low, 2.3%; moderate, 5.5%; high, 18.8%; very high 33.2%; P-trend < 0.001).

Conclusions: A simple tool based upon clinical risk factors and MPI variables predicts 2-year cardiac events. Risk stratification between the low and very high groups was greater than tenfold.

Keywords: Myocardial perfusion imaging; clinical prediction rule; coronary artery disease; gated SPECT.

Figure 1.

Percentages of individuals classified by CRAX2MACE as low (<5%), moderate (5.0–9.9%), high (10–19.9%) and very high risk (20% or greater).

Figure 2.

Observed 2-year risk for the primary outcome of MACE (upper left panel) and individual secondary outcomes (AMI, death, coronary revascularization) according to CRAX2MACE predicted risk category. Error bars are 95% confidence intervals.