Trisomy 13 is a rare chromosomal disorder in which all or a percentage (mosaicism) of cells contain an extra 13th chromosome. Sinus of Valsalva aneurysms are rare, with an incidence of 0.1% to 3.5% of all congenital heart defects. This article reports the case of a patient with trisomy 13 with a new systolic murmur found to have a ruptured sinus of Valsalva aneurysm diagnosed on coronary computed tomography angiography. This is the first case to report sinus of Valsalva aneurysm rupture secondary to Streptococcus viridans endocarditis in a patient with trisomy 13 syndrome and highlights the importance of coronary computed tomography angiography in noninvasive imaging and surgical planning.