(Disclaimer: This article is for scientific use only, and relevant information in the following content has been processed to protect patient privacy.) Abstract: This female patient female presented with symptoms such as chest tightness and shortness of breath and decreased activity endurance after single-chamber pacemaker implantation surgery. Upon examination, the patient’s cardiac ultrasound suggested severe heart failure, and after excluding non-myocardial ischemia leading to decreased cardiac function, it was considered to be caused by pacemaker syndrome. Subsequently, the patient’s heart failure was actively corrected, and with the adjustment of pacemaker parameters, the patient’s symptoms were significantly relieved and her condition was controlled and stabilized. The patient was treated with oral medication (aspirin enteric solution tablets, Tegretol tablets, Rosuvastatin calcium tablets, spironolactone tablets, furosemide tablets, valsartan hydrochlorothiazide tablets) + pacemaker parameter adjustment. The patient’s chest tightness was relieved and her condition was controlled. The patient, Ms. Wang, 52 years old, had a single-chamber pacemaker implanted in May 2020. He could not even lie down at night, and complained that he could not climb one floor without feeling chest tightness and breathlessness, and felt that his symptoms had returned to the feeling before the pacemaker surgery. Subsequently, the patient completed a cardiac ultrasound examination and found that the left heart ejection fraction dropped to 35%, suggesting that the patient’s left ventricular systolic function was only half of that of a normal adult, so the patient’s activity tolerance was significantly reduced. When asked whether the pacemaker helped the patient, the patient said that he felt that the pacemaker did not improve his quality of life, but made him suffer from chest tightness and breathlessness again, which seriously undermined the confidence of the patient and his family in their future life. The patient was given aspirin enteric tablets and Tegretol tablets for antiplatelet therapy, resuprastatin calcium tablets for lipid-lowering therapy, spironolactone tablets and furosemide tablets for diuretic therapy, and valsartan hydrochlorothiazide tablets for The patient was given spironolactone tablets and furosemide tablets for diuretic treatment and valsartan hydrochlorothiazide tablets for antihypertensive treatment. The coronary angiography examination was completed as soon as possible, and the examination results showed that the patient had coronary artery atherosclerosis and coronary artery dilatation. However, since the patient’s heart vessels were not significantly stenosed and would not cause heart failure, it was considered that the patient might be accompanied by pacemaker syndrome. So the pacemaker threshold and sensitivity were further tested to minimize the pacing voltage of the patient’s pacemaker, reduce the stimulation of the pacing discharge on the myocardium, reduce the number of pacing per minute, and lower the patient’s pacemaker base heart rate to 50 beats per minute. III. Treatment effect After adjusting the pacemaker parameters, reducing the voltage output and decreasing the number of pacing, the patient’s heart was significantly less affected by the stress brought by the pacemaker. Although the number of pacing was reduced by 10 beats per minute, the patient’s heart was still rested to a certain extent after several days of accumulation, and the clinical symptoms of heart failure such as chest tightness and breath-holding were significantly improved, and the patient could lie flat during sleep at night. The patient was hospitalized for about 15 days, and a repeat cardiac ultrasound examination showed that the patient’s cardiac function had increased to 45% (normal values are above 50%). With the improvement of symptoms, the patient regained confidence in life and had a desire for a better life. After 3 months of medication observation and outpatient follow-up, the patient’s heart failure symptoms have basically disappeared and he is now a member of the square dance. IV. Precautions We are glad that the patient’s symptoms related to the pacemaker syndrome have been significantly relieved, but we still need to advise the patient that even if he does not feel any discomfort in daily life, it is necessary to come to the hospital for regular follow-up and perfect cardiac examination. In case of discomfort, it is important to return to the hospital in a timely manner, perform pacemaker program control, clarify the pacemaker event log for the presence of adverse events, and improve cardiac ultrasound examinations. In addition, after discharge from the hospital, patients need to avoid staying up late, straining and strenuous exercise in daily life to avoid increasing the load on the heart and causing a relapse of the disease. In terms of diet, patients should avoid spicy, stimulating or cold foods, and mainly eat a light diet with a reasonable mix of nutrients. At the same time, patients should pay attention to maintain an optimistic and cheerful mood, which helps to stabilize the disease and promote the early recovery of the organism. V. Personal insight The patient in this article has a history of pacemaker surgery and consequently symptoms of heart failure, so it is highly important to be alert to the disease of pacemaker syndrome. In clinical practice, most of the factors of pacemaker syndrome are caused by inappropriate pacing or discharge of the pacemaker, and the symptoms may lead to new heart problems when they are severe.