Cardiac Strain Imaging Predicts Mortality in SAH

May 17, 2019

Measuring wall strain of the heart appears to be a good prognostic indicator of brain injury and risk of short-term mortality in patients with subarachnoid hemorrhage (SAH), a new study shows.

"Strain imaging is a type of echo imaging showing how the wall of the heart changes in shape in the cardiac cycle. It is becoming a mainstream measure of cardiac function, in addition to ejection fraction, in patients with heart failure or valve disease," senior author John Gorcsan III, MD, Washington University, St. Louis, Missouri, told Medscape Medical News.

"The fascinating finding about our study is that strain imaging of the heart gave prognostic information in subarachnoid hemorrhage patients who were mostly middle-aged women with no preexisting heart disease," Gorcsan said. "It shows how closely the brain and heart are related."

Gorcsan explained that a subarachnoid hemorrhage occurs when an aneurysm in the brain ruptures unexpectedly, causing a rapid increase in pressure in the brain. "This results in a high stress state and an explosion of catecholamines, which causes effects on the heart," he said.

"We found that strain imaging of the heart identified subarachnoid hemorrhage patients who were not going to do well. Patients with impaired wall strain had the highest risk of adverse events, especially in-hospital death," he added. "Wall strain appears to be a better prognostic indicator than ejection fraction or wall motion, and it gives additional prognostic information to other measures of neurological impairment."

Gorcsan said it's interesting that this measure of heart function provides information on prognosis in patients not dying of cardiac causes. "The degree of impairment of the heart seems to be related to the degree of neurological injury," he noted. "It is probably a reflection of the amount of catecholamines released, which is related to the amount of brain injury, so the function of the heart is acting as a window to what’s going on in the brain."

Gorcsan said strain imaging could be a useful test to perform on subarachnoid hemorrhage patients, one that is noninvasive and easy to do. "We found both left ventricular and right ventricular strain was related to prognosis," he noted. "Patients with more extensive cardiac impairment – with both ventricles involved — had the worse prognosis.”

The study was published online May 15 in JACC: Cardiovascular Imaging

Neurocardiac Injury

In the study, the authors explain that although subarachnoid hemorrhage most often occurs in younger to middle-aged female patients without a history of heart disease, various degrees of associated neurocardiac injury may occur, and even modest degrees of neurocardiac injury have been associated with a worse physical and functional prognosis.

They note that strain imaging by speckle tracking echocardiography may be a more sensitive marker of cardiac damage than conventional parameters such as left ventricular ejection fraction and wall motion score index. This study was conducted to investigate whether myocardial strain imaging in the acute phase of subarachnoid hemorrhage may quantify neurocardiac injury and provide additional prognostic information to routine clinical measurements.

For the study, 255 consecutive patients with acute subarachnoid hemorrhage being treated in the intensive care unit underwent echocardiography studies within 72 hours of the hemorrhage.

Results showed that abnormal left ventricular global longitudinal strain (GLS) was more strongly associated with in-hospital mortality than left ventricular ejection fraction, even after adjusting for clinical severity (odds ratio 3.11).

Furthermore, abnormal left ventricular global longitudinal strain remained significantly associated with in-hospital mortality, even after adjusting for known factors associated with outcome after subarachnoid hemorrhage, including Hunt-Hess grade, a measure of neurologic function.

Right ventricular strain was measured in 72% of patients and was found to be additive to left ventricular global longitudinal strain for predicting in-hospital mortality (P = .007).

In an accompanying editorial, Federico Asch, MD, and Diego Medvedofsky, MD, both from MedStar Health Research Institute at Washington Hospital Center, Washington, DC, say that "while much is still to be understood about the interaction between the neurological system, acute subarachnoid hemorrhage, stress, catecholamines and the myocardium, [the current study] provides an important new piece to neuro-cardiology puzzle."

Asch and Medvedofsky point out that some immediate questions arise from the findings. "If the catecholamine surge occurring in acute SAH induces stress-induced cardiomyopathy and increases the risk for in-hospital death… is there a role for beta and/or alpha-blockers in the acute treatment of these patients?... Should every patient have an echocardiogram with strain analysis?"

"Whether it is by proving prognostic value, detecting subclinical disease or improving interdisciplinary medical care, the clinical value of myocardial deformation and strain keeps growing," the editorialists add. "We look forward to further progress in neuro-cardiology and to further understanding cardiac diseases and myocardial injury with the development of strain technologies."

This study was supported by a grant from the National Institutes of Health. Gorcsan has received research grants from Medtronic, GE Healthcare, Biotronik, Hitachi, and EBR Systems. The editorialists have disclosed no relevant financial relationships.

JACC: Cardiovascular Imaging. Published online May 15, 2019. Abstract, Editorial

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