Stress CMR in patients with obesity: insights from the Stress CMR Perfusion Imaging in the United States (SPINS) registry

Abstract

Aims: Non-invasive assessment and risk stratification of coronary artery disease in patients with large body habitus is challenging. We aim to examine whether body mass index (BMI) modifies the prognostic value and diagnostic utility of stress cardiac magnetic resonance imaging (CMR) in a multicentre registry.

Methods and results: The SPINS Registry enrolled consecutive intermediate-risk patients who presented with a clinical indication for stress CMR in the USA between 2008 and 2013. Baseline demographic data including BMI, CMR indices, and ratings of study quality were collected. Primary outcome was defined by a composite of cardiovascular death and non-fatal myocardial infarction. Of the 2345 patients with available BMI included in the SPINS cohort, 1177 (50%) met criteria for obesity (BMI ≥ 30) with 531 (23%) at or above Class 2 obesity (BMI ≥ 35). In all BMI categories, >95% of studies were of diagnostic quality for cine, perfusion, and late gadolinium enhancement (LGE) sequences. At a median follow-up of 5.4 years, those without ischaemia and LGE experienced a low annual rate of hard events (<1%), across all BMI strata. In patients with obesity, both ischaemia [hazard ratio (HR): 2.14; 95% confidence interval (CI): 1.30-3.50; P = 0.003] and LGE (HR: 3.09; 95% CI: 1.83-5.22; P < 0.001) maintained strong adjusted association with the primary outcome in a multivariable Cox regression model. Downstream referral rates to coronary angiography, revascularization, and cost of care spent on ischaemia testing did not significantly differ within the BMI categories.

Conclusion: In this large multicentre registry, elevated BMI did not negatively impact the diagnostic quality and the effectiveness of risk stratification of patients referred for stress CMR.

Keywords: obesity; prognosis; stress cardiac MRI.

Figure 1

Study quality. Quality rating of cine, perfusion, and LGE sequences, according to BMI category. BMI, body mass index; LGE, late gadolinium enhancement.

Figure 2

Cardiovascular outcomes event rates. Annualized rates of primary (left) and secondary (right) outcomes, stratified by presence vs. absence of ischaemia, according to BMI category. Primary outcome = cardiovascular death or non-fatal MI. Secondary outcome = cardiovascular death, non-fatal MI, hospitalization for unstable angina, hospitalization for congestive heart failure, and unplanned late CABG. BMI, body mass index; CABG, coronary artery bypass grafting; MI, myocardial infarction.

Figure 3

Cumulative incidence rate. Time-to-event curves for primary (A) and secondary (B) outcomes, stratified by presence vs. absence of ischaemia and obesity.

Figure 4

Coronary angiography and revascularization at 90 days. Referral to invasive coronary angiography and revascularization at 90-day post-stress cardiac magnetic resonance imaging according to BMI category, by the presence (right panel) and absence (left panel) of ischaemia. BMI, body mass index.

Figure 5

Costs of downstream ischaemia testing at 4 years. Cumulative costs of downstream cardiac tests incurred during follow-up with breakdown by modality and across BMI categories, by presence (right panel) and absence (left panel) of ischaemia. Costs are in US dollars spent per patient. BMI, body mass index.