The negative effects of obesity on heart, especially the electrophysiology of the heart

Figures & data

Table 1. Different indicators in ventricular electrophysiology.

Indicators	Definition or formula	Significance
QT	QT is measured from the start of the Q wave to the end of the T wave.	Represents ventricular electrical activity.
QTc	$\mathit{QTc}=QT/\sqrt{RR}$ (Bazett formula) $\mathit{QTc}=QT/\sqrt{RR3}$ (Fridericia formula) QTc = QT + 0.154 (1 − RR) (formula 3) QTc = 317.15+(7.47 × BMI) +(−0.28*BMI (2)) + (0.005 × BMI (3)) + (−0.00003 × BMI (4)) (formula 4)	Bazett formula can correct the error caused by the heart rate, but there are cases of insufficient correction or over correction, while Fridericia formula can avoid this disadvantage. When assessing the risk of death for 30 days or 1 year, formula 3 are more effective. Formula 4 can provide convenience for people to establish the cardiovascular risk in the OP immediately.
QTd	QTd = QTMAX−QTMIN	A sign of general abnormalities in VR
Tpe or TaTe	Tpe is measured from the peak of T wave to the end of T	An indicator of total dispersion of repolarization (TDR), and associate with arrhythmia
Tpe−d	Tpe−d = TpeMAX−TpeMIN	The same as Tpe
Tpe/QT		The same as Tpe
JT drugs	JT = QT−QRS	JT is used to evaluate the efficacy of anti-arrhythmic
JTc	JTc = QTc−QRS	The same as JT
JTa	The interval between the J point and the apex of the T wave	Associate with arrhythmia
TaTe	The interval between the apex of the T wave and the end of the T wave	The same as JTa

Abbreviations: BMI: body mass index.

Figure 1. Measurement of RV indicators. The measurement of QT starts from the Q wave to the end of the T wave, including the QRS wave, the ST segment, and the T wave. JT is defined as the QT to remove the QRS wave portion. Tpe starts from the T peak and ends at the T wave. JTa is the interval between the J point and the apex of the T wave b. When there is a U wave, the T wave end is defined as the lowest point of the curve between the T wave and the U wave.c. In the p-wave inverted electrocardiogram, the representation of QT interval, Tpe, JT and JTa.d. In the bi-peak ECG of T wave, the representation of QT interval, Tpe, JT and JTa.

Figure 2. Metabolic abnormalities caused by obesity and CVD.

Table 2. The association of obesity and cardiac indicators.

Groups	Indicators	Results	References
OP didn’t combine with other diseases	QT, QTc, QTd, QTd-apex,Tpe, Tpe-d, Tpe/QT, P, QRS, LVM	OP associate with a statistically significant increase in QT, QTc, QTd, QTd‐apex, Tpe, Tpe‐d, and Tpe/QT compared to normal subject; Leftward shifts of the P wave QRS and T wave axes, various changes in OP wave morphology, low QRS voltage could be seen in obese subjects; In OP, LVM may affect QTc; Weight loss associated with a significant education in QTd and QTc.	[6,24,25,26,27,28,29] [6] [27] [24,25,26]
OP combined with obesity-related diseases	P, QRS, QTc, QTd, LVH, CV (RR), HRV	Obesity and its related diseases such as hypertension and diabetic were positively correlated with P, QRS, QTc, QTd, LVH, and negatively correlated with CV (RR) and negatively correlated with CV (RR).	[30,31–35]
Male	QT, QTc	In the male population, obesity was associated with prolonged exposure to these VR indicators.	[36,37]
Female	P, QTd, QTc, LVM	Obesity leaded to a significant increase in P wave dispersion, LVM, QTc and QTd.	[38,39,40–43]
Children	QTc, QTd, JTd, TDR, LVM, LVM index	LVM, LVM index, TDR, JTd, QTc and QTd were significantly greater in OP than in the control group.	[44,45,46–48]
Race	QTc, resting heart rate	Among Mexican Americans, persons with obesity were more likely to have longer QTc intervals and higher resting heart rates.	[49]
Animal mod	QRS, Q, T, QTd, resting heart rate	Q wave and T amplitude were reduced, while R amplitude, QTd and resting heart rate increase; Compensatory shortened QT interval and decreased QRS amplitude could be seen in overweight rats.	[50]

Abbreviations: LVM: Left ventricular mass; LVH: left ventricular hypertrophy; CV (RR): coefficient of variation of RR intervals; HRV: heart rate variability; TDR: transmural dispersion of repolarization.

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