Application of stress-only myocardial perfusion imaging

Single-photon emission computed tomography myocardial perfusion study is usually a sequence of stress and rest part. In case of a normal stress study rest part can be given up. The objective of this study was to examine factors affecting concordance of results of stress-only (SO) and stress-rest (SR) studies.

SO and SR studies without and with attenuation correction (AC) of 212 selected patients (without cardiomyopathy, history of myocardial infarction or coronary artery bypass grafting) were analyzed visually. Influence of percutaneous coronary intervention (PCI) in the past, type of stress (physical/pharmacological) and application of AC (in form of combined method of non-corrected and corrected images - CM), patient body mass index (BMI) and gender on concordance rates of SO and SR studies were examined.

Neither a history of PCI, nor a type of stress affected concordance rate. AC (in form of CM) improved concordance rate significantly, from 60% to 68% (p = 0.018). Patient BMI affected concordance rates - 72% in non-obese and 59% in obese patients (p = 0.05). In the whole group, risk of overlooking patients with abnormal perfusion in SO study was small (< 2%), but it grew significantly with patient BMI. Rest study was necessary in about 20% of non-obese and in about 50% of obese patients.

MPS can be limited to stress part in appropriately selected, especially non-obese, patients provided that AC is applied, due to a low risk of overlooking patients with abnormal perfusion. In case of obese patients, careful analysis of exercise images for their normality is particularly important.