Myocardial contrast echocardiography assessment of perfusion abnormalities in hypertrophic cardiomyopathy

Abstract

Background Perfusion defects during stress can occur in hypertrophic cardiomyopathy (HCM) from either structural or functional abnormalities of the coronary microcirculation. In this study, vasodilator stress myocardial contrast echocardiography (MCE) was used to quantify and spatially characterize hyperemic myocardial blood flow (MBF) deficits in HCM. Methods Regadenoson stress MCE was performed in patients with septal-variant HCM (n = 17) and healthy control subjects (n = 15). The presence and spatial distribution (transmural diffuse, patchy, subendocardial) of perfusion defects was determined by semiquantitative analysis. Kinetic analysis of time-intensity data was used to quantify MBF, microvascular flux rate (β), and microvascular blood volume. In patients undergoing septal myectomy (n = 3), MCE was repeated > 1 years after surgery. Results In HCM subjects, perfusion defects during stress occurred in the septum in 80%, and in non-hypertrophied regions in 40%. The majority of septal defects (83%) were patchy or subendocardial, while 67% of non-hypertrophied defects were transmural and diffuse. On quantitative analysis, hyperemic MBF was approximately 50% lower (p < 0.001) in the hypertrophied and non-hypertrophied regions of those with HCM compared to controls, largely based on an inability to augment β, although hypertrophic regions also had blood volume deficits. There was no correlation between hyperemic MBF and either percent fibrosis on magnetic resonance imaging or outflow gradient, yet those with higher degrees of fibrosis (≥ 5%) or severe gradients all had low septal MBF during regadenoson. Substantial improvement in hyperemic MBF was observed in two of the three subjects undergoing myectomy, both of whom had severe pre-surgical outflow gradients at rest. Conclusion Perfusion defects on vasodilator MCE are common in HCM, particularly in those with extensive fibrosis, but have a different spatial pattern for the hypertrophied and non-hypertrophied segments, likely reflecting different contributions of functional and structural abnormalities. Improvement in hyperemic perfusion is possible in those undergoing septal myectomy to relieve obstruction. Trial registration ClinicalTrials.gov NCT02560467. Graphical Abstract

Primary versus iatrogenic (post-PCI) coronary microvascular dysfunction: a wire-based multimodal comparison

“…In line with this explanation, patchy hyperemic perfusion defects at microvascular bed has been previously reported in the setting of the hypertrophic cardiomyopathy without obstructive coronary artery disease (CAD). 29 In the current study, mean hyperemic ST – shift (mV) in both groups were similar which implies the presence of same magnitude of reversible ischaemia in Type-1 and Type-4 CMD groups.…”

Enhancing Prediction of Myocardial Recovery After Coronary Revascularization: Integrating Radiomics from Myocardial Contrast Echocardiography with Machine Learning

“… 29 Additionally, the emphasis on end-systolic images is crucial because during systole, the myocardium thickens and the minute intramyocardial vessels collapse, predominantly leaving the capillaries as the main contributors to the microbubble signal. 30 Analyzing images from this specific phase effectively minimizes interference from intramyocardial vessel signals, thus allowing for a more accurate extraction of radiomics features indicative of myocardial perfusion and viability.…”

Imaging cardiac hypertrophy in hypertrophic cardiomyopathy and its differential diagnosis

“…Myocardial contrast echocardiography has improved our ability to detect left ventricular aneurysms and thrombi, as well as clearly delineate the thickened segments within the myocardium [7 ▪▪ ,12 ▪ ,21 ▪ ]. Preliminary data suggest the feasibility of assessing myocardial perfusion in patients with HCM [22 ▪ ].…”