The goal of this observational study is to improve quality of life in sinus node dysfunction patients by utilizing allometric lower rate pacing (or called personalized lower rate, PLR) in standard commercially available dual-chamber pacemakers.

The primary objective is to achieve a significant improvement in patients' quality of life with use of PLR pacing in comparison with the control group with nominal lower rate in patients with implanted dual-chamber pacemaker.

The secondary objectives are to assess cardiac functional changes in echocardiography of ventricular mechanical performance with a PLR pacing in comparison with the control group with nominal lower rate, and to assess the viability of using elevated blood pressure as a marker for undetected bradycardia and providing allometric rate to correct bradycardia-related increase in arterial systolic blood pressure.

Inclusion Criteria:

• Patients are at age of equal to or more than 60 years old
• Patients have plan to implant dual-chamber pacemaker
• Resting sinus heart rate is equal or less than 60 bpm, or average heart rate detected through 24-hour dynamic electrocardiogram is equal or less than 60 bpm
• Patients have diagnosis of SND. If patients have both sinus node dysfunction and AV block, conduction system pacing shall be available
• Patients have a history of hypertension, two times of blood pressure measurements at office visit are equal to or more than 130 mmHg in systolic blood pressure, diastolic pressure is equal or less than 80 bpm

Exclusion Criteria:

• Patients have or possible concomitant a diagnosis of heart failure, either reduced EF or preserved EF
• Patients have persistent or chronic atrial fibrillation or clinically significant paroxysmal atrial fibrillation
• Previously diagnosed with a history of organic heart disease: including congenital heart disease, coronary heart disease, old myocardial infarction, dilated cardiomyopathy, hypertrophic cardiomyopathy, cardiac amyloidosis, long QT syndrome, etc.
• Patients have a known secondary cause of hypertension
• Patients have hospitalization of a hypertensive emergency in the previous year
• Patients have a history of renal disease or renal-artery diseases
• Severe hepatic or renal dysfunction
• Active acute infection
• Patients cannot submit a signed informed consent form
• Patients are pregnant or plan to be pregnant during study period
• Patients participate in another study that will confound this study

The three sites locate in the north, west and south of China respectively and are all Tertiary A hospitals. This study will enroll 70 subjects who meet all the inclusion and exclusion criteria from the in-patients from the three hospitals.