The QT interval is the time from the beginning of the QRS complex, representing ventricular depolarization, to the end of the T wave, resulting from ventricular repolarization.
The R wave is the first upward deflection after the P wave and part of the QRS complex. The R wave morphology itself is not of great clinical importance but can vary at times.
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Atherosclerotic coronary artery disease (CAD) affects the coronary arteries, which deliver blood to the myocardium.
Atrial fibrillation is the most common chronic arrhythmia, characterized by erratic atrial electrical activity with atrial rates of 400 to 600 beats per minute.