Abstract
Introduction/Background
Preterm birth has adverse consequences on the cardiovascular system. Whether premature birth is associated with conduction and repolarisation abnormalities past childhood and into adulthood still needs to be demonstrated. An exercise test could reveal such abnormalities.
Objectives
We aimed to assess electrocardiographic changes, particularly corrected QT (QTc) prolongation, in a cohort of young adults born preterm, at rest and during exercise.
Design/Methods
We analysed the ECG of young adults (23.9±3.1 years) born term (≥37 weeks, n=53) and preterm (<30 weeks, n=49) at rest, peak exercise and 3 minutes into recovery during an exercise test on a cycle ergometer. We measured PR, QRS and QT intervals, calculated the QTc, and determined blood calcium, magnesium, potassium and fasting glucose.
Results
Mean gestational age was 39.7±1.1 and 27.3±1.3 weeks for the term and the preterm groups, respectively. Apart from an increased heart rate at rest in individuals born preterm, no significant difference was found between both groups for any other ECG parameters at rest (Table 1). None of the participants had a severely prolonged QTc (>500ms) at rest; exercise revealed severely prolonged QTc in two participants including one in the preterm group. The use of QT-prolonging medications did not influence ECG parameters in either groups.
Table 1.
Electrocardiography measurements. Data are presented as mean ±SD or n (%). P-value calculated using Student’s t-test or the Fisher exact test. HR, heart rate; QTc, QT corrected with Bazett’s formula.
| Outcome measurements | Preterm | Term | P- Value |
|---|---|---|---|
| At rest | n=49 | n=53 | |
| HR, bpm | 98 ± 22 | 90 ± 17 | 0.032 |
| QTc, ms | 408 ± 34 | 409 ± 31 | 0.899 |
| QRS, ms | 85 ± 10 | 84 ± 13 | 0.684 |
| PR, ms | 141 ± 27 | 149 ± 26 | 0.128 |
| At peak exercise | n=38 | n=41 | |
| HR, bpm | 180 ± 14 | 178 ± 13 | 0.631 |
| QTc, ms | 387 ± 34 | 387 ± 23 | 0.906 |
| QRS, ms | 75 ± 12 | 75 ± 10 | 0.773 |
| PR, ms | 104 ± 18 | 106 ± 15 | 0.683 |
Conclusion
We observed no significant difference in electrocardiographic measurements between young adults born preterm and term. Current results do not support avoidance of QT-prolonging medications in individuals born preterm.