CHADS2 Score and Stroke Risk in Patients with Atrial Fibrillation

August 18, 2010

Patients who receive recommended treatment for atrial fibrillation earlier face lower risk of stroke and other serious secondary side effects. A patient's CHADS2 score is a reliable indicator of stroke risk.

According to research from the Sahlgrenska Academy, Institute of Medicine, Department of Molecular and Clinical Medicine, University of Gothenburg, Sweden, investigators have found that the CHADS2 score is “correlated with the risk of being affected by stroke in patients with acute coronary syndromes and with or without atrial fibrillation.”

To calculate a patient’s CHADS2 score (Congestive heart failure, Hypertension, Age > 75 years, Diabetes, prior Stroke or TIA), used to determine whether a patient requires anticoagulation and/or antiplatelet therapy, one point each is assigned for congestive heart failure, hypertension (consistent blood pressure of 140/90 mmHg or if receiving medication for hypertension), age if older than 75 years, and diabetes mellitus; two points are assigned if the patient has had a prior stroke or TIA (transient ischemic attack).

This JAMA article cites research that found that the “stroke rate per 100 patient-years without antithrombotic therapy” increases “by a factor of 1.5 (95% CI, 1.3-1.7)” for each one-point increase in CHADS2 score. Annual stroke risk based on CHADS2 score is as follows:

0: 1.9% (95% CI 1.2—3.0)

1: 2.8% (2.0—3.8)

2: 4.0% (3.1—5.1)

3: 5.9% (4.6—7.3)

4: 8.5% (6.3—11.1)

5: 12.5% (8.2—17.5)

6: 18.2% (10.5-27.4)

Patients with CHADS2 scores of 0-1 are at low to moderate risk for stroke, and are candidates for treatment with aspirin or warfarin; a score of 2 or greater indicates patients are candidates for “permanent treatment with oral anticoagulation.”

For the Swedish study, researchers followed 2,335 patients with acute coronary syndromes, including myocardial infarction, 442 of whom were diagnosed with atrial fibrillation. Dritan Poçi, senior Consultant in Cardiology at Örebro University Hospital, reported that an increase in CHADS2 score was associated with a greater risk for stroke during long-term follow-up, as well as a greater risk for early (30-days) or long-term death. “This score was well applied and the results correlated even in patients with acute coronary syndromes and without atrial fibrillation. This means that the score, the CHADS2 score, may help to identify patients with high risk for subsequent stroke or death,” said Poçi.

Poçi said that these results demonstrate that CHADS2 score should be used to assess stroke risk in all patients who have been diagnosed with atrial fibrillation, and perhaps should be calculated even in patients without atrial fibrillation but who are presenting with symptoms of myocardial infarction. “It would increase the possibility of identifying and treating important risk factors. Such an individual treatment of these categories of patients may reduce the risk of subsequent diseases and increases the survival of patients,” said Poçi.

Additional reading:

Click here to access an online CHADS2 score calculator.

CardioMath iPhone app enables you to calculate your patients’ CHADS2 score, which is currently “the best validated and most clinically useful model for assessing the stroke risk for patients with non-valvular atrial fibrillation.” CardioMath also feature 70 additional commonly used formulas in cardiovascular medicine.

The Balance between Stroke Prevention and Bleeding Risk in Atrial Fibrillation: A Delicaet Balance Revisited