Background: Apical hypertrophy cardiomyopathy (ACM) is a rare condition characterized by asymmetric myocardial hypertrophy of the apex of the left ventricle. When two-dimensional echocardiography is limited by a poor acoustic window, patients are often referred for MRI. Our hypothesis is that a cheaper and more widely available diagnostic modality like myocardial perfusion single photon emission computed tomography (SPECT) may be helpful in the diagnosis of ACM.
Objective: The purpose of this prospective study was to define the characteristics of rest and stress SPECT studies in patients with known ACM, and whether SPECT may be helpful in the diagnosis of ACM.
Methods: Adult patients with ACM were enrolled in the study. Diagnosis was made with 2-D echo. A rest and exercise or dipyridamole stress SPECT study was performed in all patients with Tc-99m sestamibi.
Results: We enrolled 20 patients (mean age 60 +/- 16 years), 9 were female, with ACM. SPECT at rest revealed in 15 patients (75%) an increased apical tracer uptake, a spade-like deformity of the left ventricular chamber, and the "Solar Polar" map pattern consistent with ACM. The sensitivity, specificity, positive predictive value, and negative predictive value of SPECT for detecting ACM were 75%, 100%, 100%, and 80%, respectively.
Conclusion: Three-fourths of adult patients with ACM showed, on myocardial perfusion SPECT, characteristic findings which were not seen in age-matched control subjects, such as a significant increased apical tracer uptake, a spade-like deformity of the left ventricle, and the "Solar Polar" map. Nuclear physicians should be aware of these SPECT findings because many ACM patients may first end up in the nuclear labs due to their markedly abnormal ECG for exclusion of obstructive coronary artery disease.