The Effect of Obesity on Echocardiographic Image Quality.

Background: Increased body mass index (BMI) may reduce transthoracic echocardiogram (TTE) image quality, resulting in increased requirements for ultrasound enhancing agents (UEA), as recommended by the American Society of Echocardiography (ASE), and a greater incidence of non-diagnostic studies.

Methods: Over a 5-month period 1,108 TTEs were analysed as to (1) whether they could answer the clinical question posed by the ordering physician (i.e. were diagnostic vs non diagnostic), and (2) whether they required UEAs according to the ASE guidelines. Patient characteristics were gathered from the medical record.

Results: 12.9% of TTEs were non-diagnostic (21.0% of TTEs in the obese population [BMI≥30 kg/m] vs 7.8% in the non-obese [p<0.001]). Predictors of a non-diagnostic study were BMI (OR 1.09, [95% CI 1.06-1.11], p<0.0001), male gender (OR 1.54, [1.06-2.25], p=0.02), and inpatient status (OR 1.75, [1.20-2.55], p=0.004). Obesity (BMI≥30) was strongly associated with non-diagnostic studies (OR 3.22, [2.23-4.51], p<0.001). Factors associated with increased requirement of UEAs were BMI (OR 1.10, [1.08-1.12], p<0.0001), age (OR 1.02, [1.01-1.03], p<0.0001) and inpatient status (OR 1.7, [1.29-2.24], p<0.05). Obesity (BMI>30) was strongly associated with contrast requirement (OR 3.16, [2.43-4.10], p<0.0001).

Conclusions: Body mass index, male gender and inpatient status were associated with an increased incidence of non-diagnostic studies. Body mass index, age and inpatient status were associated with an increased requirement for UEAs.