Cryptogenic TIA and stroke had a similar 10-year recurrence risk compared to non-cardioembolic subtypes (32% vs 27%; p=0.91), but presented with fewer atherosclerotic and cardioembolic markers.
Observational (n=2,555)
Does cryptogenic TIA and ischaemic stroke have a different risk factor profile and long-term prognosis compared to other stroke subtypes in patients with a first TIA or ischaemic stroke?
Cryptogenic TIA and stroke account for a third of events and have similar recurrence rates to other subtypes, despite having fewer traditional atherosclerotic and cardioembolic risk factors.
Absolute Event Rate: 32% vs 27%
p-value: p=0.91
BACKGROUND: A third of transient ischaemic attacks (TIAs) and ischaemic strokes are of undetermined cause (ie, cryptogenic), potentially undermining secondary prevention. If these events are due to occult atheroma, the risk-factor profile and coronary prognosis should resemble that of overt large artery events. If they have a cardioembolic cause, the risk of future cardioembolic events should be increased. We aimed to assess the burden, outcome, risk factors, and long-term prognosis of cryptogenic TIA and stroke. METHODS: In a population-based study in Oxfordshire, UK, among patients with a first TIA or ischaemic stroke from April 1, 2002, to March 31, 2014, we compared cryptogenic events versus other causative subtypes according to the TOAST classification. We compared markers of atherosclerosis (ie, risk factors, coronary and peripheral arterial disease, asymptomatic carotid stenosis, and 10-year risk of acute coronary events) and of cardioembolism (ie, risk of cardioembolic stroke, systemic emboli, and new atrial fibrillation AF during follow-up, and minor-risk echocardiographic abnormalities and subclinical paroxysmal AF at baseline in patients with index events between 2010 and 2014). FINDINGS: Among 2555 patients, 812 (32%) had cryptogenic events (incidence of cryptogenic stroke 0·36 per 1000 population per year, 95% CI 0·23-0·49). Death or dependency at 6 months was similar after cryptogenic stroke compared with non-cardioembolic stroke (23% vs 27% for large artery and small vessel subtypes combined; p=0·26) as was the 10-year risk of recurrence (32% vs 27%; p=0·91). However, the cryptogenic group had fewer atherosclerotic risk factors than the large artery disease (p<0·0001), small vessel disease (p=0·001), and cardioembolic (p=0·008) groups. Compared with patients with large artery events, those with cryptogenic events had less hypertension (adjusted odds ratio OR 0·41, 95% CI 0·30-0·56; p<0·0001), diabetes (0·62, 0·43-0·90; p=0·01), peripheral vascular disease (0·27, 0·17-0·45; p<0·0001), hypercholesterolaemia (0·53, 0·40-0·70; p<0·0001), and history of smoking (0·68, 0·51-0·92; p=0·01), and compared with small vessel and cardioembolic subtypes, they had no excess risk of asymptomatic carotid disease (adjusted OR 0·64, 95% CI 0·37-1·11; p=0·11) or acute coronary events (adjusted hazard ratio HR 0·76, 95% CI 0·49-1·18; p=0·22) during follow-up. Compared with large artery and small vessel subtypes combined, patients with cryptogenic events also had no excess of minor-risk echocardiographic abnormalities (cryptogenic 37% vs 45%; p=0·18) or paroxysmal AF (6% vs 10%; p=0·17) at baseline or of new AF (adjusted HR 1·23, 0·78-1·95; p=0·37) or presumed cardioembolic events (1·16, 0·62-2·17; p=0·64) during follow-up. INTERPRETATION: The clinical burden of cryptogenic TIA and stroke is substantial. Although stroke recurrence rates are comparable with other subtypes, cryptogenic events have the fewest atherosclerotic markers and no excess of cardioembolic markers. FUNDING: Wellcome Trust, Wolfson Foundation, UK Stroke Association, British Heart Foundation, Dunhill Medical Trust, National Institute for Health Research, Medical Research Council, and the NIHR Oxford Biomedical Research Centre.
Li et al. (Mon,) conducted a observational in First TIA or ischaemic stroke (n=2,555). Cryptogenic TIA and ischaemic stroke vs. Non-cardioembolic stroke (large artery and small vessel subtypes combined) was evaluated on 10-year risk of recurrence (p=0.91). Cryptogenic TIA and stroke had a similar 10-year recurrence risk compared to non-cardioembolic subtypes (32% vs 27%; p=0.91), but presented with fewer atherosclerotic and cardioembolic markers.