Tisdale et al reported a score for predicting QTc interval prolongation in a hospitalized patient. The authors are from Purdue University, Indiana University and Krannert Institute of Cardiology.
Patient selection: hospitalized patient
Parameter:
(1) age in years
(2) sex
(3) loop diuretic
(4) serum potassium in mmol/L
(5) admission QTc in ms
(6) acute myocardial infarction
(7) number of QTc prolonging drugs
(8) sepsis
(9) heart failure
Parameter
Finding
Points
age in years
< 68 years
0
>= 68 years
1
sex
male
0
female
1
loop diuretic
no
0
yes
1
serum potassium
> 3.5 mmol/L
0
<= 3.5 mmol/L
2
admission QTc
< 450 ms
0
>= 450 ms
2
acute MI
no
0
yes
2
number of QTc prolonging drugs
0
0
1
3
>= 2
3 (or 6)
sepsis
no
0
yes
3
heart failure
no
0
yes
3
total score =
= SUM(points for all 9 parameters)
Interpretation:
• minimum score: 0
• maximum score: 18 or 21 (21 is given in the paper; to achieve this a person would have to be scored for both 1 and GTE 2 QTc prolonging drugs. Effectively this means a person receiving GTE 2 drugs would be given 6 points)
• The higher the score the greater the risk for QTc prolongation.
Score
Risk QTc Prolongation
0 to 6
low
7 to 10
moderate
>= 11
high
where:
• According to Figure 1 a score of 0 or 1 would have a very low risk.
• According to Figure 1 a score >= 16 would be very high.
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