Prevalence and Predictors of Ischemia and Outcomes in Outpatients With Diabetes Mellitus Referred for Single-Photon Emission Computed Tomography Myocardial Perfusion Imaging

Abstract

Background The prevalence of ischemia and its prediction of events are unclear in outpatient diabetic patients in the modern era of intensive medical management. We sought to identify the prevalence of ischemia, subsequent cardiac events, and impact of gender, stress type, and symptom status on these findings in a cohort of outpatient, stable diabetic patients referred for SPECT myocardial perfusion imaging (MPI). Methods and Results The study cohort included 575 consecutive diabetic outpatients who underwent quantitative, gated-SPECT MPI. Clinical information, stress MPI variables, and cardiac events were prospectively collected and analyzed. The study population was at intermediate risk of coronary artery disease (CAD) or had known CAD (40.3%); 29% were asymptomatic at the time of stress testing. Scintigraphic ischemia and significant (≥10%) left ventricular (LV) ischemia were present in 126 (21.9%) and 29 (5.0%), respectively, and <1% had early revascularization. The risk of ischemia was increased >2-fold by male gender (p<0.001) but was not impacted by pharmacologic stress (p=0.15) or presence of symptoms (p=0.89). Over median 4.4 years follow-up, the rate of cardiac death/nonfatal myocardial infarction (MI) was moderate at 2.6%/year (cardiac death 0.8%/year) in the total cohort but was 5.7%/year in those with ischemia (p<0.001). Pharmacologic stress predicted a higher cardiac event rate (p<0.001) but symptoms did not (p=0.55). Conclusions This stable outpatient diabetic SPECT referral cohort had low rates of significant ischemia and early revascularization; an initially-low initial cardiac event rate increased after 2 years. Independent predictors of cardiac death/nonfatal MI were known CAD, pharmacologic stress, and MPI ischemia. Nearly one-third of those with events had a normal MPI, indicating a need for improved risk stratification.

Cardiovascular risk stratification in diabetic patients: Is all in METS?

“…Remarkably, the prevalence of ischemia and its prediction of events are unclear in outpatients with diabetes mellitus in the modern era of intensive medical management. Bourque et al 28 recently sought to identify the prevalence of ischemia, subsequent cardiac events, and impact of sex, stress type, and symptom status on these findings in a cohort of stable outpatients with diabetes mellitus referred for MPS. Known CAD was present in 40.3% of subjects and 29% were asymptomatic at the time of stress testing.…”

“…Noteworthy, in this study nearly one third of patients with events had a normal MPS, indicating a need for improved risk stratification. 28 Thus, the relationship among METS, stress-induced ischemia, and prognosis in diabetic subjects remains unclear. In another recent study, Duvall et al 29 showed that a provisional injection protocol defined as age \65, normal rest ECG, no history of CAD, and high level exercise (C10 METS) with a negative ECG response and no symptoms has a very low 5-year all-cause mortality and low yield of MPS.…”

Seguimiento a Cinco Años en Pacientes Diabéticos Sin Síntomas Cardíacos Estudiados Con Perfusión Miocárdica

“…Alrededor de 1/3 de los pacientes con eventos tenían SPECT normal, lo que para los autores indica que se requiere mejorar la estratificación previo al estudio con SPECT. 17 Esto último, diferencia ese trabajo del nuestro en el que no se había solicitado el examen como parte de su manejo habitual. De acuerdo al estudio DIAD en DM asintomáticos cardíacos, el uso de estudios con provocación de isquemia no se aconseja entre otras causas por la baja capacidad de detección de la prueba, número de eventos relativamente bajo que no parecen afectar la evolución y además su alto costo.…”

Screening asymptomatic patients with type 2 diabetes: The debates persist

“…It has been observed that the prevalence of high risk CAD and ischemia on stress imaging in diabetic patients may be decreasing, presumably because of both effective primary and secondary prevention (11). This correlates well with the overall decrease in significant inducible ischemia seen in patients referred for stress SPECT imaging (12).…”

“…Bourque et al (11) prospectively evaluated 575 consecutive diabetic patients (29% asymptomatic) who underwent stress SPECT myocardial perfusion imaging. Ischemia of ≥10% of the left ventricle was seen in only 5.0% of the patients imaged.…”