Researchers develop stroke risk score for patients with MI, heart failure—but not AFib

A team of researchers has developed a risk score containing five readily available factors that predict the odds of stroke for heart attack patients with reduced ejection fraction but without atrial fibrillation (AFib).

Using a pooled cohort of 22,904 such patients—including 660 who suffered stroke—Joao Pedro Ferreira, MD, PhD, and colleagues developed and validated the score based on the following factors: older age, Killip class 3 or 4, estimated glomerular filtration rate of less than 45 ml/min/1.73 m², hypertension history and previous stroke. All risk factors were assigned one point except for previous stroke (three points) and age (two points for ages 60-75, three points for older than 75).

“The models were well calibrated and showed moderate to good discrimination (C-index = 0.67),” Ferreira et al. reported in the Journal of the American College of Cardiology. “The observed three-year event rates increased steeply for each sextile of the stroke risk score (1.8 percent, 2.9 percent, 4.1 percent, 5.6 percent, 8.3 percent and 10.9 percent, respectively) and were in agreement with the expected event rates. … This score may help in the identification of patients with MI and HF (heart failure) and a high risk for stroke despite their not presenting with (AFib).”

Much more work has been aimed at assessing the stroke risk of patients with AFib, the researchers pointed out. In fact, the “extensively validated” CHA₂DS₂-VASc score is guideline-recommended to factor into decisions on whether to treat patients with anticoagulants.

But stroke risk stratification is not as well defined for patients with MI and heart failure but no AFib, even though they are at higher risk than the general population. Notably, the authors found their tool outperformed CHA₂DS₂-VASc for the AFib-less study population (C-index 0.67 vs. 0.63, respectively).

Ferreira and colleagues said patients with AFib have about twice the risk of stroke as their entire study population, equivalent to a patient without AFib drawing a score of three or higher using their prediction model. This suggests patients without AFib with a score of at least three may benefit from anticoagulants, just as they are recommended for individuals with AFib.

“However, practical decisions regarding anticoagulation in this study group warrant prospective and randomized evidence before any such advice is provided,” the researchers noted.

Ferreira et al. pointed out patients in their study may have developed AFib during follow-up or had unreported paroxysmal AFib, making it unlikely the entire population was truly without AFib throughout follow-up. They cautioned their findings couldn’t be applied to patients with preserved ejection fraction and said the type of stroke patients experienced wasn’t available in the dataset.