Impaired Left Ventricular Contractile Reserve in Patients With Hypertrophic Cardiomyopathy and Abnormal Blood Pressure Response: A Stress Echocardiographic Study

Background: Abnormal blood pressure response (ABPR) has been reported to be a risk factor for sudden cardiac death in patients with hypertrophic cardiomyopathy (HCM). We aimed to elucidate the relationship between ABPR during exercise stress echocardiography (ESE) and impaired left ventricular (LV) contractile reserve based on two-dimensional strain in patients with HCM. Methods: Patients with HCM underwent ESE with treadmill exercise. Patients whose blood pressure elevation at maximum workload was lower than 20 mmHg from baseline were classified as having ABPR. Echocardiographic parameters were compared between patients with and without ABPR. Results: Of 26 patients with HCM, nine patients were diagnosed with ABPR. Significant LV outflow tract obstruction (>50 mmHg) was provoked only in one patient with ABPR (baseline to the conclusion of the exercise, 15.2 mmHg to 63.0 mmHg). Change in cardiac output (CO) and the ratio of early diastolic velocity to early annular velocity (E/e') from baseline to just after the conclusion of exercise did not differ between patients with and without ABPR (CO, 102±40% vs. 122±45%, P = 0.19; E/e', 4±22% vs. 2±20%, P = 0.86). Change in systemic vascular resistance change was not significant (patients with vs. without ABPR, -52±10% vs. -46±13%, P = 0.24). Percent change in LV global longitudinal strain was lower in patients with ABPR than patients without ABPR (12±17% vs. 27±15%, P = 0.02). Conclusion: In conclusion, impaired LV contractile reserve during exercise might contribute to ABPR in patients with HCM.