Open AccessReliability of qt intervals as indicators of clinical hypercalcemia
Author(s) -
Ahmed R.,
Hashiba K.
Publication year - 1988
Publication title -
clinical cardiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.263
H-Index - 72
eISSN - 1932-8737
pISSN - 0160-9289
DOI - 10.1002/clc.4960110607
Subject(s) - medicine , reliability (semiconductor) , reliability engineering , cardiology , power (physics) , physics , quantum mechanics , engineering
Abstract Reliability of corrected QT intervals (QoTc, QaTc, and QeTc) as indicators of clinical hypercalcemia was assessed in 14 hypercalcemic patients. Hypercalcemia was severe to extreme (serum calcium 14.9 to 22.8 mg/dl) in 11, moderate (13.4 mg/dl) in 1, and mild (12.2 and 11.8 mg/dl) in 2 patients. QT intervals during hypercalcemia were compared with those during normocalcemia either before or after development of hypercalcemia. QeTc interval showed neither significant correlation with serum calcium nor any consistent pattern of change with development of hypercalcemia or normalization of serum calcium. In contrast, QoTc and QaTc intervals shortened with development of hypercalcemia and returned toward normal with normalization of serum calcium in all the patients, and showed significant correlation with serum calcium (QoTc: r = ‐0.77, p < 0.001, n = 35; QaTc: r = 0.82, p < 0.001, n = 35). QaTc was short (> 0.30 s) in all the ECGs in severe and moderate hypercalcemia and in 2 of the 5 ECGs in mild hypercalcemia. Combination of short QoTc ( < 0.18 s) and short QaTc was found to be highly specific for, and was present in 65% of ECGs, in moderate and severe hypercalcemia. Combination of normal QoTc (> 0.18 s) and normal QaTc (> 0.30 s) was not observed in moderate or severe hypercalcemia. We conclude that QoTc and QaTc intervals are reliable indicators of clinical hypercalcemia.