Effect of intravenous ondansetron on QT interval prolongation in patients with cardiovascular disease and additional risk factors for torsades: a prospective, observational study

Figures & data

Table 1 Demographic and clinical characteristics of patients

Characteristic	Principal diagnosis on admission
	Heart failure (n = 16)	ACS (n = 24)
Demographics
Age (mean ± SD years)	55 ± 18	54 ± 14
Female (%)	8 (50)	12 (50)
Comorbidities (%)
Anemia	3 (19)	1 (4)
COPD/asthma	2 (13)	4 (17)
Chronic pain	2 (13)	2 (8)
Dementia	2 (13)	1 (4)
Depression	6 (38)	6 (25)
Diabetes	4 (25)	4 (17)
DVT/PE	6 (38)	4 (17)
Old myocardial infarction	5 (31)	5 (21)
Heart failure	16 (100)	5 (21)
Hypertension	6 (38)	13 (54)
Hyperlipidemia	5 (31)	20 (83)
Osteoarthritis	1 (6)	2 (8)
Pneumonia	2 (13)	1 (4)
Renal insufficiency	3 (19)	2 (8)
Schizophrenia	2 (13)	2 (8)
Seizure disorder	2 (13)	1 (4)
Stroke/transient ischemic attack	1 (6)	1 (4)
Chronic urinary tract infections	1 (6)	0 (0)
Risk factors for QTc prolongation (%)
Acute coronary syndromes	0 (0)	24 (100)
Bradycardia	1 (6)	1(4)
Congenital long QTc syndrome	0 (0)	0 (0)
Female gender	8 (50)	12 (50)
Heart failure	16 (100)	5 (21)
Hypokalemia	6 (38)	13 (54)
Hypomagnesemia	5 (31)	5 (21)
Old myocardial infarction	5 (31)	5 (21)
QTc >500 msec at baseline^†	3 (19)	5 (21)
Receiving >1 QTc-prolonging medication	10 (63)	15 (63)
Number of patients with only 1 risk factor for QTc prolongation*	9 (56)	8 (33)
Number with ≥2 risk factors for QTc prolongation*	7 (44)	16 (67)

Notes:

* Not including principal diagnosis of either heart failure or acute coronary syndromes;

† see Table 2 for specific medications.

Abbreviations: ACS, acute coronary syndromes; COPD, chronic obstructive pulmonary disease; DVT, deep vein thrombosis; PE, pulmonary embolism; QTc, QT interval corrected for heart rate; SD, standard deviation.

Table 2 Description of QTc-prolonging medications

Scheduled medication	Patients, n (%)	Risk of QTc prolongation*	Time receiving medication prior to ondansetron exposure	Half-life (hours)
Levofloxacin	4 (10)	Possible	5 days to 14 days	6–8
Citalopram	8 (20)	Possible	1 month to 5 years	35
Erythromycin^†	4 (10)	Accepted	5 days to 10 days	4.6–7.8
Haloperidol	1 (3)	Accepted	3 days to 4 days	14
Methadone	4 (10)	Accepted	1 year to 3 years	7–60
Ranolazine	8 (20)	Possible	45 days to 3 years	7–9
Risperidone	3 (8)	Possible	1 year to 5 years	3–20
Quetiapine	2 (5)	Possible	6 months to 4 years	6
Tizanidine	3 (8)	Possible	8 days to 3 years	2.5
Ziprasidone	3 (8)	Possible	2 months to 3 years	2–7
Venlafaxine	5 (13)	Possible	2 months to 4 years	5

Notes:

† Used for gastrointestinal motility in patients with diabetes.

* QTc risk as determined by the Center for Education and Research at the University of Arizona.

Abbreviation: QTc, QT interval corrected for heart rate.

Table 3 Summary of QTc interval changes

QTc outcomes	Principal diagnosis		Total population n = 40
	Heart failure n = 16	ACS n = 24
Baseline, mean ± SD, msec	443 ± 53	444 ± 45	444 ± 47
Baseline, median, msec	435	430	430
Baseline, range, msec	360–570	390–570	360–570
Two hours post-drug, mean ± SD, msec	466 ± 60	463 ± 45	464 ± 50
Two hours post-drug, median, msec	450	450	450
Two hours post-drug, range, msec	410–590	420–580	410–590
Mean change ± SD, msec	20.6 ± 20*	18.3 ± 20**	19.30 ± 18**

Notes:

* P < 0.0012;

** P < 0.0001.

Abbreviations: ACS, acute coronary syndromes; SD, standard deviation; QTc, QT interval corrected for heart rate.