Background & Purpose: Patent foramen ovale (PFO) can be detected in up to 43% of patients with cryptogenic cerebral ischemia undergoing investigation with transesophageal echocardiography (TEE). The diagnostic value of transthoracic echocardiography (TTE) in the detection of PFO in patients with cryptogenic cerebral ischemia has not been compared with that of transcranial Doppler (TCD) using a comprehensive meta-analytical approach.
Methods: We performed a systematic literature review according to PRISMA guidelines to identify all prospective observational studies of patients with cryptogenic cerebral ischemia that provided both sensitivity and specificity measures of TTE, TCD or both compared to the gold standard of TEE.
Results: Our literature search identified 35 eligible studies including 3067 patients. The summary sensitivity and specificity for TCD was 96.1% (95% confidence interval: 93.0%-97.8%) and 92.4% (95%CI: 85.5%-96.1%), whereas the respective measures for TTE were 45.1% (95%CI: 30.8-60.3%) and 99.6% (95%CI: 96.5-99.9%). The summary diagnostic odds ratio (DOR) for TCD (DOR=297.97, 95%CI: 131.18-676.83) and TTE (DOR=193.44, 95%CI: 30.38-1231.67) did not significantly differ (z-value=0.418, p=0.676). TTE was superior in terms of higher positive likelihood ratio values (LR+= 106.61, 95%CI: 15.09-753.30 for TTE vs. LR+=12.62, 95%CI: 6.52-24.43 for TCD; p=0.043), while TCD yielded lower negative positive likelihood values (LR- = 0.04, 95%CI: 0.02-0.08) compared to TTE (LR- =0.55, 95%CI: 0.42-0.72; p<0.001). Finally, the area under the summary receiver operating curve was significantly greater (p<0.001) in TCD (AUC=0.98, 95%CI: 0.97-0.99; Figure A) compared to TTE studies (AUC=0.86, 95%CI: 0.82-0.89; Figure B).
Conclusions: TCD is more sensitive but less specific compared to TTE for the detection of PFO in patients with cryptogenic cerebral ischemia. The overall diagnostic yield of TCD appears to outweigh that of TTE.