Eclampsia and abnormal QTc.

Background: Abnormalities of calcium and magnesium metabolism are known risk factors for QT interval prolongation and have been reported in eclampsia.

Objective: To determine if eclampsia is associated with QT abnormalities

Methods: In a prospective study, the QT interval corrected for heart rate (QTc), serum calcium, magnesium and potassium were compared among 30 intrapartum eclamptics and 30 age, parity and gestational age-matched women with uncomplicated pregnancy

Results: Primigravidae made up 93.3 % of patients. Mean age was 19.5+/-4.2 years Blood pressure was significantly higher among patients than controls (163.0+/-34.7mmHg versus 120.4+/-18.6mmHg systolic, p<0.05) and (104.7+/-15.2mmHg versus 79.6+/-10.7mmHg, p<0.05). Heart rate ranged from 76 to 163 beats per minute (bpm) and 65 to 112bpm among patients and controls respectively. The corresponding QTc were 390-572 and 390-460 respectively. Compared to the controls, patients had significantly higher mean heart rate (121.1+/-24.9bpm versus 89.3+/-12.9bpm, p<0.05) and higher QTc (470.4+/-42.4 versus 436.3+/-17.7; p<0.05). Compared to the controls, the eclamptics also had higher frequency of sinus tachycardia (90% versus, 13.3%) Odd Radio (OR) =29.57; 95% Confidence Interval (CI) = 5,87-174.08, p=0.00), abnormal QTc (46.7% versus 6.6%, OR = 9.2; 95% CI =1.61-68.48, p=0.01) and T-axis deviation (26.6% versus 3.3%, OR=10.55, 95% CI=1.2-244.3, p=0.03) Serum calcium level was significantly lower among patients than controls (2.0+/-0.4mmol/L versus 2.3+/-0.2mmol/L, p<0.05). The eclamptics had higher frequency of hypocalcaemia than the controls (40 % versus 6.6%; OR = 14, 95% Cl = 1.58-316.9, p=0.01). Serum magnesium, potassium, urea and creatinine levels were similar between the two groups.

Conclusion: Eclampsia is associated with abnormal QTc that may be related to maternal hypocalcaemia. Correction of electrolyte abnormalities and cautions about agents that have potential for QT prolongation are vital in the care of eclamptics.