Introduction: New diffusion weighted imaging (DWI) lesions are very common after cardiothoracic surgery. However, most of these lesions are asymptomatic and what determines whether a lesion would be symptomatic or not remains unclear.
Hypothesis: New ischemic lesions are more likely to be symptomatic if large and if affecting primary motor areas.
Methods: Patients over 65 years undergoing surgical aortic valve replacement (AVR) for calcific stenosis were prospectively recruited (n=196). All patients underwent neurological evaluation on post-op days 1, 3, and 7, and MRI scans on planned post-op day 5. Among those with new post-op DWI lesions, we compared baseline characteristics, surgery, and imaging data between subjects who were symptomatic and asymptomatic.
Results: Of the 129 patients who completed a post-surgical MRI, 79 (61%) had new DWI lesions and 17 of those (22%) had new neurological symptoms. New symptoms were associated with longer times on bypass (132±43 vs. 103±36 min, p=0.006), smaller intra-operative drops in arterial pressures (28±2 vs. 40±15 mm Hg, p=0.001), and more concomitant procedures (59% vs. 29%, p=0.047). Symptomatic patients had a greater number of new DWI lesions (5±8 vs. 3±3, p=0.012), higher DWI total lesion volumes (7±15 vs. 1±14 mL, p=0.002), and higher old lesion burden on FLAIR (11±11 vs. 5±7 mL, p=0.028). Symptomatic lesions more frequently involved the frontal (92% vs 62%, p=0.043) and parietal white matter (67% vs 29%, p=0.020) and were more common in right hemispheric lesions (100% vs.58%, p=0.005).
Conclusions: New DWI lesions are common after AVR, but most are asymptomatic. Patients are more likely to have symptoms with right frontal and parietal involvement, with larger absolute DWI lesion count and volumes, and with longer bypass durations, complicated surgeries, and higher pre-existing lesion burdens.