Could a Stop-Smoking pill tame dangerous heart rhythms?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Aged between 18 and 80 years old (inclusive). 2. Premature ventricular contractions of ≥1000 times/average 24-hour revealed by screening (72-hour Holter monitoring). 3. Definite diagnosis of myocardial infarction for more than 4 weeks, with NYHA Class I-II. 4. Maintained on Metoprolol Succinate Sustained-release Tablets. (If other types of beta-blocker therapy were being used before screening, they must be replaced with Metoprolol Succinate Sustained-release Tablets.) 5. Understand and comply with the study procedures and methods, and sign the informed consent form. Exclusion Criteria: 1. Myocardial infarction occurring within 4 weeks. 2. NYHA Class III-IV. 3. Use of amiodarone within 1 month before screening. 4. Use of antiarrhythmic drugs, or traditional Chinese medicine, Chinese patent medicine for arrhythmia other than amiodarone within 1 week prior to screening. 5. Sustained ventricular tachycardia, ventricular flutter, or ventricular fibrillation detected during screening (non-sustained ventricular tachycardia does not need to be excluded). 6. Sick sinus syndrome without pacemaker implantation, II-III degree atrioventricular block, or bundle branch block bilateral. 7. Moderate to severe bronchial asthma or severe chronic obstructive pulmonary disease. 8. Severe renal impairment (eGFR less than 30 mL/min/1.73 m²). 9. Hyperthyroidism. 10. Severe sequelae of stroke. 11. Epilepsy, schizophrenia, or depression. 12. Pregnant or breastfeeding women, or those with a positive blood pregnancy test result before randomization. 13. Combined cancer or other diseases, with an expected life expectancy of less than 1 year. 14. Perioperative period of cardiothoracic surgery (1 week before surgery to 2 weeks after surgery). 15. Severe electrolyte disturbance. 16. Digitalis poisoning. 17. Known hypersensitivity to varenicline tartrate tablets or their excipients. 18. History of smoking and cessation for less than 1 year. 19. Individuals taking varenicline tartrate tablets for smoking cessation. 20. Currently participating in other clinical studies. 21. Other conditions making the subjects unsuitable for enrollment as determined by the investigator.