Abstract 4144203: "Blueberry On Top" Phenomenon. A Novel Strain Pattern In Patients With Apical Variant Hypertrophic Cardiomyopathy.

Introduction/Background: We have recently described “blueberry-on-top” phenomenon as a novel echocardiographic strain pattern in patients with apical variant hypertrophic cardiomyopathy (ApHCM). This so called "inverse-amyloid" pattern is identified when there is impaired peak systolic strain with paradoxically advanced time to peak strain in a hypertrophied apex with relatively spared strain in the basal segments. On a standard polar map, peak systolic strain will have a pale center while time to peak strain will depict a more robust blue center. Research Questions/Hypothesis: While a “blueberry-on-top” pattern has been vaguely observed in a few prior reports, its true prevalence in patients with ApHCM is currently unknown. We sought to examine the prevalence of this strain pattern among patients with ApHCM. Methods/Approach: A series of patients diagnosed with ApHCM, confirmed by cardiac MRI, were included. Patients with apical aneurysm, prior myocardial infarction, or aortic stenosis were excluded. All patients had a standard transthoracic echocardiogram. For uniform reporting, all echocardiogram studies were post-processed using Tomtec (Build No. 514944, Germany) which is a vendor-independent speckle tracking analysis software. Both peak longitudinal strain and time to peak strain values were exported into a standard color-coded polar map (bull's eye plot). A pixel-averaged polar map of all patients included was generated using a python script developed using an open CV library. Results/Data: From a cohort of 340 patients with HCM, 14 patients with ApHCM were included. Mean age was 66 years, and 50% were males. Mean LVEF was 69%. Mean scar burden by LGE quantification was 12% which is mostly localized to the hypertrophied apex. In patients who had genetic testing (n=10), half of patients had either pathogenic mutation or variant of unknown significance (VUS). About two thirds of patients had a strain pattern (inverted T waves) on EKG. Baseline characteristics are summarized in table 1 . A “blueberry-on-top” strain pattern was observed in 92% (n=13) of patients, while one patient had a distorted strain pattern due to apical foreshortening. A pixel-averaged polar map of all patients is shown in figure 1 . Conclusions: This is the first-in-human report establishing the prevalence of “blueberry-on-top” strain pattern in a series of patients with ApHCM. This newly recognized strain pattern is unique and can be used as a supportive diagnostic feature in patients with ApHCM.