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Incidence of symptomatic hemorrhage in patients with lobar microbleeds

Ellis S van Etten¹, Eitan Auriel¹, Kellen E Haley¹

¹From the Department of Neurology, Massachusetts General Hospital, Boston.

|June 21, 2014

Abstract

Background And Purpose:

Lobar microbleeds suggestive of cerebral amyloid angiopathy (CAA) are often identified on MRI in the absence of lobar intracerebral hemorrhage (ICH). We compared the baseline characteristics and risk of subsequent ICH among such patients to those presenting with CAA-related lobar ICH.

Methods:

Clinical data (demographics, risk factors), apolipoprotein E genotype, neuroimaging markers of CAA severity (microbleed counts, leukoaraiosis volume), and clinical outcomes (incidence rates of ICH and death during a mean follow-up of 5.3±3.8 years) were compared between 63 patients enrolled because of incidentally found microbleeds and 316 with CAA-related ICH, in our prospectively enrolled cohort. Predictors of incident ICH were explored in the microbleed-only patients using multivariable Cox regression models.

Results:

Microbleed-only patients shared similar demographic, apolipoprotein E, and vascular risk profiles with lobar ICH patients, but had more lobar microbleeds (median, 10 versus 2; P<0.001) and higher leukoaraiosis volumes (median, 31 versus 23 mL; P=0.02). Microbleed-only patients had a nontrivial incidence rate of ICH, not different from patients presenting with ICH (5 versus 8.9 per 100 person-years; adjusted hazard ratio, 0.58; 95% confidence interval, 0.31-1.06; P=0.08). Microbleed-only patients had a higher mortality rate (hazard ratio, 1.67; 95% confidence interval, 1.1-2.6) compared with ICH survivors. Warfarin use and increasing age were independent predictors of future ICH among microbleed-only patients after correction for other covariates.

Conclusions:

Patients presenting with isolated lobar microbleeds on MRI have a genetic, neuroimaging, and hemorrhagic risk profile suggestive of severe CAA pathology. They have a substantial risk of incident ICH, potentially affecting decisions regarding anticoagulation in clinical situations.

Insights

Patients with isolated cerebral amyloid angiopathy (CAA) microbleeds on MRI have a high risk of future intracerebral hemorrhage (ICH). Warfarin use and increasing age independently predict ICH in these patients, impacting anticoagulation decisions.

Area of Science:

Neurology
Radiology
Genetics

Background:

Lobar microbleeds on MRI often indicate cerebral amyloid angiopathy (CAA) but can occur without overt intracerebral hemorrhage (ICH).
Understanding the risk profile of patients with isolated microbleeds is crucial for managing CAA.

Purpose of the Study:

To compare baseline characteristics and subsequent ICH risk in patients with incidental lobar microbleeds versus those with established CAA-related ICH.
To identify predictors of incident ICH in patients with isolated lobar microbleeds.

Main Methods:

A prospective cohort study compared 63 patients with incidental microbleeds to 316 with CAA-related ICH.
Data included demographics, risk factors, apolipoprotein E genotype, neuroimaging markers (microbleed count, leukoaraiosis), and outcomes (ICH incidence, death) over a mean follow-up of 5.3 years.
Multivariable Cox regression identified ICH predictors in the microbleed-only group.

Main Results:

Microbleed-only patients had more microbleeds and higher leukoaraiosis than ICH patients, despite similar demographics and risk profiles.
The incidence rate of ICH was substantial in microbleed-only patients (5 per 100 person-years) and not significantly different from ICH patients (8.9 per 100 person-years).
Microbleed-only patients had a higher mortality rate; warfarin use and increasing age were independent predictors of future ICH.

Conclusions:

Isolated lobar microbleeds suggest severe CAA pathology with a significant risk of future ICH.
These findings have implications for anticoagulation decisions in patients with incidental microbleeds.

Read full analysis

Keywords:

cerebral amyloid angiopathy cerebral hemorrhage cerebral microbleeds magnetic resonance imaging

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