M. Meier et al., QTc interval and scintigraphically assessed myocardial perfusion in newly diagnosed and long-term type 1 diabetes mellitus, J DIABET C, 14(2), 2000, pp. 90-95
In diabetes mellitus, heart rate corrected QT interval (QTc) has been sugge
sted to be related to ischemic heart disease and increased risk of sudden c
ardiac death. The aim of the study was to analyze the length of QTc interva
l with regard to global and regional myocardial perfusion in type 1 diabeti
c patients. Myocardial perfusion was investigated in 20 newly diagnosed and
40 long-term type 1 diabetic patients without clinical evidence for corona
ry artery disease by means of Tc-99-methoxyisobutylisonitrile (Tc-99m-MIBI)
-scintigraphy (myocardial uptake (MU) score: 1-6). Five consecutive RR and
QT intervals of resting electrocardiogram (ECG) tracing were measured and c
orrected for the previous cycle length. EGG-based cardiac autonomic neuropa
thy (CAN) was assessed with five cardiac reflex tests. Length of QTc interv
al was 423 +/- 29 ms in newly diagnosed and 433 +/- 26 ms in long-term type
1 diabetic patients. Nine (45%) newly diagnosed and 18 (45%) long-term dia
betic patients demonstrated a prolonged QTc interval (>440 ms). Both newly
diagnosed and longterm diabetic patients did not display significant global
or regional myocardial perfusion defects (mean MU scores <3). In newly dia
gnosed diabetic patients, the length of QTc interval was related to global,
posterior and septal Tc-99m-MIBI uptake (p < 0.05, respectively). In long-
term diabetic patients, the length of QTc interval was associated with epic
al Tc-99m-MTBI uptake (p < 0.05). Two (10%) newly diagnosed and 19 (48%) lo
ng-term type 1 diabetic patients demonstrated EGG-based CAN. In long-term t
ype 1 diabetic patients, global myocardial Tc-99m-MIBI uptake did not diffe
r significantly between patients with and without CAN. QTc interval was not
significantly different between diabetic patients with and without EGG-bas
ed CAN (433 +/- 19 ms vs. 428 +/- 17 ms). Long-term diabetic patients, of w
hom 10 (25%) patients had microalbuminuria and seven (18%) patients had mac
roalbuminuria. demonstrated an association between QTc interval and albumin
uria (p < 0.05). The results somewhat suggest an association between QTc in
terval and vascular factors in type 1 diabetes mellitus. Future investigati
ons are required to analyze the role of QTc interval in the pathogenesis of
abnormalities of myocardial perfusion. (C) 2000 Elsevier Science Inc. All
rights reserved.