Subclinical episodes of Afib occurred more frequently in type 2 diabetic patients
In type 2 diabetic patients, one quarter of strokes are of unknown cause, and subclinical episodes AF may be a common etiologic factor according to a new study.
Italian researchers examined whether subclinical episodes of atrial fibrillation (AF) were associated with an increased risk of silent cerebral infarct (SCI) and stroke in diabetic patients younger than 60 years who did not have other clinical evidence of AF and cerebrovascular disease at baseline.
AFib is a type of irregular heartbeat. It occurs when one or both of the upper chambers of the heart (atria) beat erratically. This puts them out of sync with the heart’s 2 lower chambers (ventricles).
AFib affects more than 2 million people in the United States. The odds of developing AFib go up with age. In fact, the American Heart Association states that AFib is the most common serious type of irregular heartbeat in people over age 65. It’s also sometimes associated with other health problems, such as heart disease.
For the study 1,992 people were screened , with a higher predominance higher prevalence of brief subclinical episodes of atrial fibrillation at baseline in diabetics than in healthy matched controls (9% versus 1.6%, P<0.0001), note by Dr. Raffaele Marfella, MD, PhD, Department of Geriatrics and Metabolic Diseases Second University of Naples, Italy and colleagues .
After three year follow-ups diabetic patients with subclinical Afib had significantly more strokes (17.3%) than those who did not have a subclinical arrhythmia (5.9%).
The findings revealed after researchers controlled for common risk factors linked to diabetes, a two-fold risk of stroke linked with diabetes remained in those participants younger than sixty, however, only 15% of diabetic patients with stroke have a history of symptomatic atrial fibrillation, which leaves around one-quarter of diabetics whose stroke origin cannot be determined.
To see if subclinical Afib might be the origin for at least some of those strokes, Dr. Marfella and colleagues enrolled 464 type 2 diabetic patients younger than 60 years and matched them to patients without diabetes. Average age of participants was 52 years and follow-up was an average of 37 months.
Patients underwent to quarterly 48-hour ECG Holter monitoring (48HM) to detect brief subclinical episodes of AF (AF durations <48 hours.) and followed them for 37 months. The outcomes were a SCI, assessed by brain MRI, and stroke events during the follow-up.
Among the patients 176 or 38% had brief silent Afib episodes had brief silent Afib episodes (termed the SAFE [Silent AF Episode] group) and 288 (62%) did not have silent episodes, but they met clinical characteristic criteria (termed the non-SAFE group).
Diabetic patients with silent episodes of AF (SAFE-group, n=176) had higher baseline prevalence of SCI (61% versus 29%, P<0.01) and higher stroke events (17.3% versus 5.9%, P<0.01) during the follow-up period than the others (non-SAFE-group, n=288).
Confounders not significantly associated with silent Afib episodes were sex, BMI, diastolic blood pressure, plasma glucose, HbA1c, interventricular septum, and hyperlipidemia.
Episode of silent AF was an independent determinant of SCI (OR 4.441, P<0.001 C.I=2.42 to 8.16) and independent predictors for the occurrence of stroke in diabetic patients (HR, 4.6; P<0.01 C.I 2.7-9.1).
In their conclusion the researchers write “Subclinical episodes of AF occurred frequently in type 2 diabetic patients and were associated with a significantly increased risk of SCI and stroke.” “In the light of the data presented, silent brain infarcts should not be considered just intermediates in the relationship between vascular risk factors and the risk of stroke but markers for other factors, such as the brief AF episodes, that lead to stroke.”
Most of the episodes (156) of silent atrial fibrillation in the SAFE group lasted between 1 and 24 hours, with 51 lasting between 24 and 48 hours, and 12 lasting 10 minutes to 1 hour.
Only two controls had episodes of silent Afib; they lasted between 1 and 24 hours.
At three years 11% of patients in the SAFE group developed clinical atrial fibrillation compared with 4% in the non-SAFE group (P<0.01). These patients were excluded from follow-up analysis. No controls developed Afib.
Also, only one of the 43 stroke events was hemorrhagic.
The results suggest that it may be appropriate to screen diabetic patients with an event monitor and to anticoagulate those who are found to have AF.
This study appears in in the Journal of the American College of Cardiology.
Approximately 20.8 million Americans have diabetes. People with diabetes are up to 4 times as likely to have a stroke as someone who does not have the disease, mainly because many people with diabetes have health problems that are also stroke risk factors.
More information can be found online at National Stroke Association website.
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