TY - JOUR
T1 - The diagnostic utility of recovery phase QTc during treadmill exercise stress testing in the evaluation of long QT syndrome
AU - Horner, Justin M.
AU - Horner, Melissa M.
AU - Ackerman, Michael J.
N1 - Funding Information:
We acknowledge the support from the Mayo Clinic Windland Smith Rice Comprehensive Sudden Cardiac Death Program and are grateful to the patients and families who have sought clinical evaluation at Mayo Clinic's Long QT Syndrome Clinic.
Funding Information:
Dr. Ackerman's research program is supported by the Mayo Clinic Windland Smith Rice Comprehensive Sudden Cardiac Death Program.
PY - 2011/11
Y1 - 2011/11
N2 - Background: Nearly 40% of patients with long QT syndrome (LQTS) can have a nondiagnostic QTc at rest. Treadmill and cycle exercise stress testing are used in the diagnostic evaluation of LQTS. Objective: The purpose of this study was to determine the diagnostic significance of peak exercise and recovery phase QTc values during treadmill stress testing in LQTS. Methods: An Institutional Review Boardapproved, retrospective analysis was performed on the treadmill stress tests in 243 patients including 82 LQT1, 55 LQT2, 18 LQT3, and 88 genotype-negative patients dismissed as normal. Blinded to genotype, QTc was calculated at rest, peak exercise, and 1, 2, 3, 4, and 5 minutes of recovery. Results: Compared with those dismissed as normal, the average QTc was greater at all scored stages in LQT1 and LQT3 patients and at all stages in LQT2 patients except peak exercise and 1 minute of recovery (P <.01). Either an absolute QTc <460 ms during the recovery phase or a maladaptive, paradoxical increase in QTc, defined as QTc recovery - QTc baseline < 30 ms (ΔQTc), distinguished patients with either manifest or concealed LQT1 from all other subsets (P <.0001). The presence of beta-blockers did not blunt these abnormal repolarization profiles. Conclusion: Treadmill stress testing can unmask patients with concealed LQTS, particularly LQT1, with good diagnostic accuracy.
AB - Background: Nearly 40% of patients with long QT syndrome (LQTS) can have a nondiagnostic QTc at rest. Treadmill and cycle exercise stress testing are used in the diagnostic evaluation of LQTS. Objective: The purpose of this study was to determine the diagnostic significance of peak exercise and recovery phase QTc values during treadmill stress testing in LQTS. Methods: An Institutional Review Boardapproved, retrospective analysis was performed on the treadmill stress tests in 243 patients including 82 LQT1, 55 LQT2, 18 LQT3, and 88 genotype-negative patients dismissed as normal. Blinded to genotype, QTc was calculated at rest, peak exercise, and 1, 2, 3, 4, and 5 minutes of recovery. Results: Compared with those dismissed as normal, the average QTc was greater at all scored stages in LQT1 and LQT3 patients and at all stages in LQT2 patients except peak exercise and 1 minute of recovery (P <.01). Either an absolute QTc <460 ms during the recovery phase or a maladaptive, paradoxical increase in QTc, defined as QTc recovery - QTc baseline < 30 ms (ΔQTc), distinguished patients with either manifest or concealed LQT1 from all other subsets (P <.0001). The presence of beta-blockers did not blunt these abnormal repolarization profiles. Conclusion: Treadmill stress testing can unmask patients with concealed LQTS, particularly LQT1, with good diagnostic accuracy.
KW - Arrhythmias
KW - Electrocardiography
KW - Exercise
KW - Long QT syndrome
KW - Stress testing
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U2 - 10.1016/j.hrthm.2011.05.018
DO - 10.1016/j.hrthm.2011.05.018
M3 - Article
C2 - 21699858
AN - SCOPUS:80054999710
SN - 1547-5271
VL - 8
SP - 1698
EP - 1704
JO - Heart rhythm
JF - Heart rhythm
IS - 11
ER -