LIPOMATOUS HYPERTROPHY OF THE ATRIAL SEPTUM PRESENTING AS A RIGHT ATRIAL MASS

Lipomatous hypertrophy of the atrial septum (LHAS) has been associated with cardiac arrhythmias and is defined as fatty infiltration >2 cm t hick in the atrial septum. The clinical and histologic features of sur gically excised LHAS have not been previously studied. We studied 11 s urgical resections of LHAS and compared them with 13 autopsy cases of LHAS and 24 control autopsy hearts. Of 11 surgical patients, eight wer e women; patients' mean age was 63 years, and six were described as mi ldly to overtly obese. Symptoms included congestive heart failure, atr ial fibrillation, supraventricular tachycardia, palpitations, syncope, and incidental mass found at surgery. Imaging studies typically revea led a right atrial mass with a mean size of 6 cm (range, 2.5-10 cm). M ultivacuolated fat was more extensive in surgical (p = 0.005) and auto psy (p = 0.009) cases of LHAS than in control hearts. Atypical, hypert rophied myocytes were present in 72% of cases of LHAS compared with 8% of controls (p = 0.0003). In autopsy hearts, histologically abundant multivacuolated fat, heart weight, and body size were independently as sociated with increased atrial septal thickness. LHAS can be surgicall y excised, it has a distinctive histologic appearance marked by the pr esence of abundant multivacuolated fat and hypertrophied myocytes, and it is associated with increased body and cardiac mass.