Ischaemia as a cause of LVOT gradient reversal in HCM

Abstract

We present the case of a previously fit 84-year-old female with long-standing systemic hypertension and the echo phenotype of hypertrophic cardiomyopathy (HCM) - asymmetrical septal hypertrophy, significant resting left ventricular (LV) outflow obstruction and mitral regurgitation (MR) secondary to systolic anterior motion (SAM) of the mitral valve. Valsalva provocation caused an increase in LVOT dynamic gradient and MR severity. The patient presented with a progressive decrease in exercise capacity along with chest pain relieved by rest or sublingual GTN. Exercise stress echo demonstrated a paradoxical response with reduction of both LVOT gradient and severity of MR. There was evidence of inducible regional wall motion abnormalities associated with no change in LV cavity size. Coronary angiogram revealed significant triple vessel disease.

Learning points: 20% of adult HCM patients over the age of 45 years have been shown to have coexistent coronary artery disease (CAD) that is associated with a reduced overall survival. Diagnosis of CAD in patients with HCM is difficult to make based on clinical grounds because of the high incidence of angina in patients with HCM but no CAD.Reduction of LVOT gradient with stress in patients with HCM (in the absence of a vaso-vagal response) may indicate ischaemia due to significant multivessel epicardial CAD, including left mainstem stenosis. Hence, this finding during stress echocardiography suggests that further investigation of the coronaries should be considered.Exercise stress echocardiography has not been validated for the assessment of ischaemia secondary to epicardial coronary disease in patients with HCM because ischaemia in this group of patients is often caused by multiple mechanisms, including microvascular ischaemia and myocardial bridging.Comparative assessment of rest and peak exercise 2D strain may add incremental value in identifying regional wall motion abnormalities, which may be difficult to distinguish by eye in hypertrophied, dynamic myocardium.A paradoxical response to exercise with significant decrease in LVOT obstruction and MR has been reported in the literature. This is often associated with a trend toward increased exercise capacity and better prognostic outcomes. Our clinical case presents a significant decrease in LVOT obstruction and MR that was associated with a trend toward reduced exercise capacity and was caused by ischaemia.

Keywords: HCM; LVOT obstruction; ischaemia in HCM; paradoxical LVOT obstruction.

Figure 1

CMR: patchy and diffuse LV late gadolinium enhancement.