Regional postsystolic shortening in patients with hypertrophic cardiomyopathy: Its incidence and characteristics assessed by strain imaging

Background: Postsystolic shortening (PSS) is considered myocardial shortening after the point of aortic valve closure and can be observed physiologically in healthy individuals. However, the incidence and magnitude of PSS in myocardial disorders have not been investigated. Objectives. We performed strain imaging to characterize PSS in patients with hypertrophic cardiomyopathy (HCM) versus healthy individuals. Methods. Thirty patients with HCM (22 men and 8 women; mean age 62 +/- 6 years) and 30 control subjects (20 men and 10 women; mean age 61 +/- 9 years) were studied. For both groups, patterns of myocardial strain curves were assessed by the 18-segment model using apical 2-chamber, 4-chamber, and long-axis views. PSS was defined if the peak strain existed beyond aortic valve closure. The severity of PSS was assessed as postsystolic index (strain amplitude beyond aortic closure divided by whole strain amplitude) for each segment. Results. As compared with control subjects, patients with HCM had a greater isovolumic relaxation time (105 +/- 31 vs 74 +/- 28 milliseconds, P < .001), despite die comparable value of left ventricular ejection fraction (65 +/- 6% vs 65 +/- 4%, P = not significant). The number of segments having PSS was greater in patients with HCM than in control subjects (12.6 +/- 3.0 vs 8.4 +/- 3.7, P < .001). This was associated with greater values of postsystolic index in all segments for patients with HCM. In patients with HCM, the number of segments having PSS correlated significantly with the isovolumic relaxation time (r = 0.36, P < .05). Conclusions. Patients with HCM have more pathologic PSS, which may have etiologic contribution to the functional heterogeneity of this disease entity, especially diastolic dysfunction.