Objective: investigators investigated the effects of metoprolol tartrate plus Tongmai Yangxin Pill on premature ventricular complexes and cardiac function in patients with premature ventricular complex.

Methods: In total, 584 participants with premature ventricular complex will be randomly assigned (at a 1:1 ratio) into two groups: study group (metoprolol tartrate [25 mg twice per day, orally] plus Tongmai Yangxin Pill [40 pills twice per day, orally]) and control group (metoprolol tartrate [25 mg twice per day, orally] plus placebo [40 simulated pills twice per day, orally]). The total treatment period is 8 weeks.

Efficacy endpoints and safety assessment:

Primary efficacy endpoints are as follows: change in 24-h number of PVCs after treatment and effective rate of 24-h number of PVCs after treatment. Secondary efficacy endpoints are as follows: change in New York Heart Association classification; total effective rate of comprehensive effect; change in high-sensitivity C-reactive protein level; and change in echocardiography parameters (i.e., left ventricular ejection fraction, left ventricular end diastolic dimension, E/A, cardiac index, cardiac output, and stroke volume).

Inclusion Criteria:

• Lown PVC grade, II-IVA;
• in patients with coronary heart disease and comorbid PVC or non-organic heart disease, the PVC frequency was 3000-30000 times/24 h;
• New York Heart Association grade, I or II;
• ejection fraction, ≥45%;
• written informed consent to participate in the trial.

Exclusion Criteria:

• presence of bradyarrhythmia (<50 beats/min), including sinus syndrome and atrioventricular block (second or third degree atrioventricular block);
• presence of persistent ventricular tachycardia, non-persistent ventricular tachycardia, and/or persistent atrial fibrillation;
• presence of severe PVC requiring treatment with other antiarrhythmic drugs; -presence of drug-induced, electrolyte-induced, or acid-base-induced arrhythmia;
• presence of uncontrolled or severe hypertension (e.g., grade ≥3 hypertension);
• presence of uncontrolled diabetes; presence of alanine aminotransferase or aspartate aminotransferase level ≥1.5-fold above the upper limit of normal, urea nitrogen level ≥1.2-fold above the upper limit of normal, and/or blood creatinine above the upper limit of normal;
• presence of severe respiratory dysfunction or asthma;
• presence of primary hematopoietic diseases, other systemic diseases (e.g., hyperthyroidism), poor peripheral circulation perfusion, severe peripheral vascular diseases, and/or PVC with unknown etiology;
• presence of allergic constitution, mental disorder, alcoholism, and/or smoking habit;
• pregnancy or lactation;
• ongoing β-blocker treatment or contraindications to β-blocker treatment; -participation in other clinical trials within the prior 3 months;
• and other reasons for lack of suitability to participate in this study, as determined by the investigators.

Prior to the start of the study, the sponsor (or contract research organization) and statistician will make masking of the research drugs. The statistician in this study used statistical software to generate random coding table according to the method of stratified block randomization. Personnel who have no involvement in this study will paste the corresponding drug number on the drug packaging according to the random coding.