QTc dynamics during long-term Holter recording
Patients underwent long term Holter monitoring for an average of 6.2 ±
1.2 days. Median baseline QTc (defined as the median QTc during first
hour after CV) was 452 ± 52 msec and was significantly lower than the
median QTc during the continuous Holter monitoring (467 ± 47 msec,
p=0.01 for comparison). The maximal median QTc occurred 44 hours post CV
and was 474 ± 100 msec (p<0.001 for comparison with baseline
QTc). Following this peak, the QTc returned to the baseline QTc 132
hours post CV, with a median QTc was 458 ± 70 msec (p=0.58 for
comparison with baseline QTc) Figure 2. The baseline clinical
characteristics were similar between those who had significant
prolongation within the 44 hours post CV and those who developed it
after. A trend towards more Amiodarone use was seen in those who
developed a later QTc prolongation (87% vs 63%, p=0.07).