Incremental prognostic value of standard modifiable risk factor burden across SPECT myocardial perfusion categories: a study of 38 917 patients

Stress myocardial perfusion imaging with single-photon emission computed tomography (SPECT) is widely used for evaluating coronary artery disease (CAD), with total perfusion deficit (TPD) serving as a validated, automated quantitative predictor of cardiovascular events.1 Recently, attention has focused on the concept of standard modifiable cardiovascular risk factors (SMuRFs): hypertension, diabetes, dyslipidaemia, and smoking, as prognostic determinants in patients with acute coronary syndrome.2 However, whether SMuRF burden provides incremental prognostic value across SPECT perfusion categories remains unclear. This retrospective study included 38 917 patients without prior CAD referred for clinically indicated SPECT MPI at Houston Methodist Hospital. SPECT was performed per ASNC guidelines using exercise or pharmacological stress (regadenoson).3 TPD was quantified and patients were categorized as TPD = 0 (no perfusion burden), TPD >0 and ≤10% (intermediate), or TPD >10% (significant). SMuRFs: hypertension, diabetes, dyslipidaemia, and current smoking were summed (0–4). The primary endpoint was the composite of all-cause mortality or myocardial infarction. Multivariable Cox models were adjusted for age, sex, BMI, LVEF, ischaemia, and scar; incremental discrimination was assessed using the likelihood ratio test and Harrell's C-index.