Electrocardiographic QTC Interval: Short-Term Weight Loss Effects

Pietrobelli A, Rothacker D, Gallagher D, Heymsfield SB. Int J Obes Relat Metab Disord. 1997;21(2):110-114.

Objective

To determine if short-term weight loss in obese subjects living in a metabolic ward for a 7-day period has an influence on cardiac repolarization as indicated by QT interval duration.

Methods

In this study, 30 healthy overweight men and women followed a prescribed 1120 calorie diet (23% fat, 50 grams protein/day) for 7 days. The diet was comprised of a fruit-filled bar for breakfast, a Slim•Fast meal replacement shake for lunch, and soup for dinner, plus 3 additional snack bars and a vitamin/mineral supplement daily. Weight and vital signs were recorded daily. Electrocardiograms were recorded in fasting subjects on day 0 and day 7. The QT interval was measured from the earliest onset of the QRS complex to the end of the T wave.

Results

All subjects lost weight during the one week treatment period with a mean overall lost of 3.9 +/- 1.7 kg or 4.5 +/- 1.7% of initial body weight. Subjects ranged in weight loss from 2-8 kg. Systolic blood pressure decreased significantly (p=0.007) from baseline by day two of weight loss treatment and then remained stable until discharge. The final day of weight loss treatment was associated with a significant (P<0.0001) lowering of systolic blood pressure from baseline levels. The group mean QT interval decreased significantly (p<0.02) with weight reduction treatment over the 7-day period. The group mean QTc interval decreased over the 7 days of weight loss, although the change was of borderline statistical significance. (P=0.11) There was a significant correlation between baseline and day 7 QTc intervals.

Conclusion

The use of a nutritionally-balanced weight loss diet results in a significant shortening of the QT interval and marginally significant reduction in the QTc interval in healthy overweight individuals.

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