| Background. Stroke is the third leading cause of death in the US. Ten percent of stroke victims suffer adverse cardiac outcomes secondary to coronary artery disease or cardiac derangements induced by stroke. Damage to the left insula may cause impairment of the cardiac parasympathetic tone favoring the sympathetic system leading to adverse cardiac outcomes.; Methods. We performed a prospective study of 116 stroke/TIA patients: 32 left insular stroke patients (group 1) and 84 non-insular stroke/TIA patients (group 2). Adverse cardiac outcomes including cardiac death, myocardial infarction, angina and heart failure were assessed within one year of the stroke/TIA. Twenty-four hour urine vanillylmandelic acid and power spectral analyses of heart rate variability were performed on days 1 and 7, months 1, 3, 9 and 12.; Results. Symptomatic coronary artery disease (SCAD) was found in 16% of group 1 vs. 30% of group 2 (p = 0.16). On univariate analysis, group 1 was estimated to have a 1.75 times higher rate of adverse cardiac outcomes than group 2 (95% CI: 1.02--3.00, p = 0.05). In multivariate analysis, left insula stroke was an independent predictor of the outcomes. Sensitivity analysis using only stroke patients, only SCAD, and excluding angina as an outcome showed similar results. When results were stratified by SCAD, group 1 had a relative risk (RR) of 4.06 (95% CI: 1.83--9.01, p = 0.002) compared to group 2 among patients without SCAD. For those with SCAD, RR was 0.36 (95%CI: 0.06--2.13 P = 0.14). Power spectral analysis showed that there was a statistically significant increase in instability of parasympathetic tone in group 1 only and there was no statistically significant increase in instability of sympathetic tone.; Conclusions. Left insular stroke is associated with an increased risk of adverse cardiac outcomes compared to stroke in a non-insular location and TIA among patients without SCAD. A possible mechanism is impairment of the parasympathetic tone favoring the sympathetic system. In patients with SCAD, the cardioprotective effect of medications, especially beta-blockers, taken at the time of the stroke may explain lack of association between left insular stroke and adverse cardiac outcomes in this subgroup. |
