Pathophysiology, classification, and MRI parallels in microvascular disease of the heart and brain

Assessment of Microvascular Disease in Heart and Brain by MRI: Application in Heart Failure with Preserved Ejection Fraction and Cerebral Small Vessel Disease

The objective of this review is to investigate the commonalities of microvascular (small vessel) disease in heart failure with preserved ejection fraction (HFpEF) and cerebral small vessel disease (CSVD). Furthermore, the review aims to evaluate the current magnetic resonance imaging (MRI) diagnostic techniques for both conditions. By comparing the two conditions, this review seeks to identify potential opportunities to improve the understanding of both HFpEF and CSVD.

Microvascular Dysfunction as a Systemic Disease: A Review of the Evidence

Microvascular dysfunction describes a varied set of conditions that includes vessel destruction, abnormal vasoreactivity, in situ thrombosis, and fibrosis, which ultimately results in tissue damage and progressive organ failure. Microvascular dysfunction has a wide array of clinical presentations, ranging from ischemic heart disease to renal failure, stroke, blindness, pulmonary arterial hypertension, and dementia. An intriguing unifying hypothesis suggests that microvascular dysfunction of specific organs is an expression of a systemic illness that worsens with age and is accelerated by vascular risk factors. Studying relationships across a spectrum of microvascular diseases affecting the brain, retina, kidney, lung, and heart may uncover shared pathologic mechanisms that could inform novel treatment strategies. We review the evidence that supports the notion that microvascular dysfunction represents a global pathologic process. Our focus is on studies reporting concomitant microvascular dysfunction of the heart with that of the brain, kidney, retina, and lung.

Coronary microvascular dysfunction as a chronic inflammatory state: Is there a role for omega-3 fatty acid treatment?

Coronary microvascular dysfunction is a ubiquitous pathologic process that is operational in ischemia with no obstructive coronary artery disease and other cardiovascular disorders including heart failure with preserved ejection fraction. It may, in fact, be a manifestation of a multi-systemic condition of small vessel dysfunction that also affects the brain and kidneys. While the pathophysiology driving coronary microvascular dysfunction is multifactorial, chronic inflammation plays an important role. Resolution of inflammation is an active process mediated, in part, by a family of locally active mediators biosynthesized from omega-3 fatty acids, collectively referred to as specialized pro-resolving mediators. Omega-3 fatty acid treatment modulates inflammation and is associated with improved cardiovascular outcomes and attenuation of plaque progression on cardiovascular imaging. Whether omega-3 fatty acid treatment attenuates coronary microvascular dysfunction is unknown.

Impact of Encephalomalacia and White Matter Hyperintensities on ASPECTS in Patients With Acute Ischemic Stroke: Comparison of Automated- and Radiologist-Derived Scores

Background: Automated software-based Alberta Stroke Program Early CT Score (ASPECTS) on unenhanced CT is associated with clinical outcomes after acute stroke. However, encephalomalacia or white matter hyperintensities (WMHs) may result in a falsely low automated ASPECTS if such findings are interpreted as early ischemia. Objective: To assess the impact of encephalomalacia and WMH on automated ASPECTS in patients with acute stroke, in comparison with radiologist-derived ASPECTS and clinical outcomes. Methods: This retrospective three-center study included 459 patients (322 men, 137 women; median age, 65 years) with acute ischemic stroke treated by IV thrombolysis who underwent baseline unenhanced CT within 6 hours after symptom onset and MRI within 24 hours after treatment. ASPECTS was determined by automated software and by three radiologists in consensus. Presence of encephalomalacia and extent of WMHs [categorized using the modified Scheltens scale (mSS)] were also determined using MRI. Kappa coefficients were used to compare ASPECTS between automated and radiologist-consensus methods. Multivariable logistic regression analyses and ROC analyses were performed to explore the predictive utility of baseline ASPECTS for unfavorable clinical outcome (90-day modified Rankin Scale score of 3-6) after thrombolysis. Results: Median automated ASPECTS was 9, and median radiologist-consensus ASPECTS was 10. Agreement between automated and radiologist-consensus ASPECTS, expressed as kappa, was 0.68, though was 0.76 in patients without encephalomalacia and 0.08 in patients with encephalomalacia. In patients without encephalomalacia, agreement decreased as the mSS score increased (e.g., 0.78 in subgroup with mSS score <10 vs 0.19 in subgroup with mSS >20). By anatomic region, agreement was highest for M5 (κ=0.52) and lowest for internal capsule (κ=0.18). In multivariable analyses, both automated (odds ratio=0.69) and radiologist-consensus (odds ratio=0.57) ASPECTS independently predicted unfavorable clinical outcome. For unfavorable outcome, automated ASPECTS had AUC of 0.70, sensitivity of 60.4%, and specificity of 71.0%, while radiologist-consensus ASPECTS had AUC of 0.72, sensitivity of 60.4%, and specificity of 80.5%. Conclusion: Presence of encephalomalacia or extensive WMH results in lower automated ASPECTS than radiologist-consensus ASPECTS, which may impact predictive utility of automated ASPECTS. Clinical Impact: When using automated ASPECTS, radiologists should manually confirm the score in patients with encephalomalacia or extensive leukoencephalopathy.