Baseline Characteristics of the Patients
The baseline characteristics are shown in Table 1. Mean age of the patients was 57.7 ± 14.4 years, with a range between 28 and 82 years, and 30% were men. All patients had a maximal LVOT gradient of >50 mmHg, with severe symptoms. Leading clinical symptoms were dyspnea (New York Heart Association heart functional class III or IV) in 95%, angina (Canadian Cardiovascular Society class III) in 15%, and syncope /presyncope in 10% of the patients. Patient No.20 had a history of ASA and presented with a right branch bundle block (RBBB) according to ECG. No patient had a history of pacemaker or ICD implantation.
The echocardiographic and CMR measurements of each patient are shown in Tables 2. Maximal septal thickness was 20.1 ± 6.4 mm, left atrial diameter was 42.7 ± 5.7 mm, the AML length was 27.8 ± 3.4 mm and LVOT gradient was 86.5 ± 29.2 mm Hg at rest. In 16 patients with CMR, all had basal IVS hypertrophy and nine of them had mid- or apical IVS hypertrophy. (Table 2 and Figure 3). Hypertrophied and anterior displacement of the papillary muscle (DPM) was observed in 12 patients (Table 2 and Figure 3B). No patient had abnormal MV chordal attachments. Patient No.20 presented with an abnormal morphology of the IVS according to the CMR images. The middle portion of the IVS was flimsy compared with the basal and apical portions due to previous ASA.