Introduction:
Obesity and obesity related illness continues to be an epidemic in the United States and worldwide. Obesity carries substantial risk of cardiovascular disease (CVD), and symptoms (shortness of breath, decreased exercise tolerance, etc) related to CVD can be nonspecific. Stress testing may identify the cause of these symptoms in obese patients (body mass index (BMI) > 30.) Stress echocardiography has evolved to be capable of comprehensive hemodynamic assessment as well as functional and myocardial perfusion analysis and may be ideal for symptom evaluation in the obese.
Methods:
1,615 consecutive patients (52% women, age 61±41 yrs, BMI 28±6) underwent stress perfusion ECHO (treadmill in 913, supine bike in 623 and dobutamine in 79 patients) between 2012 and 2014. Imaging included contrast/perfusion imaging and multi-method assessment of regional and global left and right heart systolic and diastolic function, left ventricular (LV) volumes, quantitative valve function, left and right heart pressures, peak/mean pulmonary artery pressures, pulmonary vascular resistance, and LV mass. Standard statistical methods were used.
Results:
Of the 1,615 patients analyzed, 516 (32%) were obese patients (BMI 36±5) and in the obese group females were 48% (vs 53% in non-obese). Both groups underwent similar stress modalities (58% vs 56% treadmill, 6% vs 4% dobutamine, and 36% vs 40% bike). Diabetes (21% vs 10%) and hypertension (57% vs 44%) were more common in obese (p< 0.05).
LV mass is disproportionately higher (113±30 vs 97±33 gm/M2) in obese patients (P< 0.01). Additionally, obese patients had statistically significant findings (p< 0.01) of LV hypertrophy (62% vs 26%), diastolic dysfunction (65% vs 44%), and at least moderate pulmonary hypertension (48% vs 34%). Overall, abnormal tests were more common in obese (83% vs 59%, p<0.01). Multiple abnormalities were more common (p<0.01): 1-3 abnormalities (13% vs 16%) and > 4 abnormalities (70% vs 43%).
Unexpectedly, the data showed no statistically significant difference between obese and non-obese in the incidence of ischemia (10% vs 11%), myocardial infarction (5% vs 4%), and cardiomyopathy (6% vs 5%).
Conclusions:
Comparative analysis of the data from stress ECHO revealed obese patients had disproportionally higher LV mass index/LV hypertrophy. Stress testing provoked worse diastolic dysfunction and much worse pulmonary vascular dysfunction in the obese patients. The triad of LV hypertrophy/diastolic dysfunction/pulmonary vascular disease with provoked moderate to severe pulmonary hypertension was the main cause of symptoms in obese patients. Hemodynamic stress ECHO is the ideal modality for evaluation of nonspecific symptoms of CVD in obese patients, as it can classify the cause of symptoms and the extent of pathology. Thereby, it may be the ideal test to guide treatment.