The significance of early post-exercise ST segment normalization.

BACKGROUND: The persistence of ST segment depression in recovery signifies a strongly positive exercise treadmill test (ETT). However, it is unclear if early recovery of ST segments portends a similar prognosis. We sought to determine if persistence of ST depression into recovery correlates with ischemic burden based on myocardial perfusion imaging (MPI). METHODS: This was a retrospective analysis of 853 consecutive patients referred for exercise MPI at a tertiary academic center over a 24-month period. Patients were stratified into three groups based on the results of the ETT: normal (negative ETT), persistence (positive ETT with >1mm ST segment depression at 1minute in recovery) and early normalization (positive ETT with <1mm ST segment depression at 1minute in recovery). Summed stress scores (SSSs) were calculated then for each patient, while the coronary anatomy was reported for the subset of patients who received coronary angiograms. RESULTS: A total of 513 patients had a negative ETT, 235 patients met criteria for early normalization, while 105 patients met criteria for persistence. The persistence group had a significantly greater SSS (8.48±7.77) than both the early normalization (4.34±4.98, p<0.001) and normal (4.47±5.31, p<0.001) groups. The SSSs of the early normalization and normal groups were not statistically different and met the prespecified non-inferiority margin (mean difference 0.12, -0.66=lower 95% CI, p<0.001). Among the 87 patients who underwent an angiogram, significant three-vessel or left main disease was seen in 39.3% of the persistence group compared with 5.9% of normal and 7.4% of early normalization groups. CONCLUSION: Among patients with an electrically positive ETT, recovery of ST segment depression within 1minute was associated with a lower SSS than patients with persistence of ST depression beyond 1minute. Furthermore, early ST segment recovery conferred a similar SSS to patients with a negative ETT. These results suggest that among patients evaluated for chest pain with a positive ETT, early recovery of the ST segment during recovery is associated with a significantly less ischemic burden on subsequent MPI and thus may represent a false positive finding in exercise treadmill testing.

Cardiac Implantable Devices Management in Medical Assistance in Dying (MAiD): Review and Recommendations for Cardiac Device Clinics.

The Medical Assistance in Dying (MAiD) program has been steadily expanding in Canada, and is expected to continue to do so. There are a substantial number of Canadians with pacemakers and defibrillators, many of whom are potential MAiD recipients. There is a need for review and reflection of standardisation of cardiac device management in MAiD patients, not only because of ethical concerns, but also because of the complexity of management at end of life. This document examines the status and role of cardiac devices (pacemakers and intracardiac defibrillators) and their physiologic interactions and influences during the MAiD process, and provides recommendations for their management.

Relative contributions of visual and vestibular information on the trajectory of human gait.

Seven healthy individuals were recruited to examine the interaction between visual and vestibular information on locomotor trajectory during walking. Subjects wore goggles that either contained a clear lens or a prism that displaced the visual scene either 20 degrees to the left or right. A 5-s bipolar, binaural galvanic stimulus (GVS) was also applied at three times the subject's individual threshold (ranged between 1.2 to 1.5 mA). Subjects stood with their eyes closed and walked forward at a casual pace. At first heel contact, subjects opened their eyes and triggered the galvanic stimulus by foot switches positioned underneath a board. Reflective markers were placed bilaterally on the shoulders as the walking trajectory was captured using a camera mounted on the ceiling above the testing area. Twelve conditions were randomly assigned that combined four visual conditions (eyes closed, eyes open, left prism, right prism) and three GVS conditions (no GVS, GVS anode left, GVS anode right). As subjects walked forward, there was a tendency to deviate in the direction of the prisms. During GVS trials, subjects deviated towards the anode while walking, with the greatest deviations occurring with the eyes closed. However, when GVS was presented with the prisms, subjects always deviated to the side of the prisms, regardless of the position of the anode. Furthermore, the visual-vestibular conditions produced a larger lateral deviation than those observed in the prisms-only trials. This suggests that the nervous system examines the sensory inputs and takes into account the most reliable and relevant sensory input.