Obesity is a well-established risk factor for congestive heart failure, but the pathogenic mechanisms leading to the underlying myocardial alterations remain unclear. Di Bello’s group in Pisa, Italy, used ultrasonic backscatter analysis (IBS) (an expression of increased myocardial collagen content) to look at subclinical alterations of left ventricular (LV) structure and function in severe obesity. Sixty severely obese patients (mean age 31.8 years) with no other medical problems were enrolled, while 48 age- and sex-matched controls were recruited as control patients. All underwent conventional two-dimensional colour Doppler echocardiography, pulsed wave Doppler tissue imaging at mitral annulus level, and IBS. Furthermore an insulin resistance index was used to assess insulin resistance in the two groups. Obese patients had a greater LV mass index by height (58.5 (14) g/m2.7) than did the control subjects (37 (8) g/m2.7; p < 0.0001) because of a compensatory response to volume overload caused by a greater cardiac output (p < 0.02). There were also significant increases in left atrial dimension (p < 0.0001) and LV ejection fraction (p < 0.03) in obese patients. Pulsed wave Doppler tissue imaging also showed an impairment of diastolic LV longitudinal function and increased LV diastolic filling pressure in obese patients. The IBS values at septum level were significantly higher for the septum in the obese group (57.8 (8)%) than in the control group (42.3 (9)%; p < 0.0001), and a significant association was found between the insulin resistance index and both the IBS index of myocardial reflectivity at septum level or LV mass. Therefore obese patients exhibit myocardial structural and functional alterations related to insulin resistance and to LV volume overload, which could be considered to be the beginning of incipient obesity cardiomyopathy.
Di Bello V, Santini F, Di Cori A, et al. Obesity cardiomyopathy: is it a reality? An ultrasonic tissue characterization study.
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