Table 3 Effects of metformin on atrial arrhythmias: reports from clinical trials

Taiwanese DM patients treated with metformin alone vs. other meds

(mean age 58 years)

Longitudinal cohort/85,198 metformin users and 560,512 non-users/mean follow-up 5.4 years

Various dose and duration of metformin

- ↓ AF incidence in the first 3 years after diagnosis of DM

- HR of 0.81, p < 0.0001

Metformin associated with decreased incidence of AF during the first 3 years after the diagnosis of DM

[44]

Taiwanese DM patients w/ or w/o metformin

(mean age 69 years)

Nested case control study/2882 AF and 11,528 controls/mean DM duration 3.9 years

- Various dose

- At least 6 months of drug used

- ↓ AF incidence

- OR 0.81, 95%CI 0.71–0.95

Metformin associated with decreased new onset AF

[55]

Hospitalized DM patients with AMI w/ or w/o metformin

(mean age 56)

Retrospective cohort/40 Metformin alone and 705 others/28-day post AMI

Various dose

- Metformin alone: <-> 28-day AF incidence, OR 1.1 (95%CI 0.3–4.0)

- Metformin + other anti-DM drugs: ↓28-day AF incidence, OR 0.2 (95% CI 0.1–0.7)

Metformin in combination with other anti-DM drugs associated with decreased AF incidence 28-day post AMI

[56]

≥ 65 years old Taiwanese DM patients w/ or w/o metformin

(mean age 73 years)

Nested case-control/1958 cases and 7832 controls/mean DM duration 8 years

- Various dose

- At least 12 months of drug used

- <-> AF incidence

- OR 1.01 (0.88–1.15)

Metformin was not associated with decreased AF incidence in elderly DM population

[57]

Patients without DM undergoing cardiac surgery randomized to metformin or placebo

(mean age 65 years)

Double-blind, randomized controlled trial/57 to metformin, 57 to placebo/24-h post reperfusion

Metformin 500 mg TID for 3 days before surgery

- <-> 24-h post reperfusion Trop I level and arrhythmia

Short-term metformin pre-surgery did not decrease perioperative myocardial injury or AF in non-DM undergoing cardiac surger

[68]

DM pts undergoing cardiac surgery w/ or w/o metformin

(mean age 66 years)

Retrospective matched cohort/metformin 635, non-metformin 648/post-op until hospital discharge

Metformin ≥ 500 mg any time prior to surgery

- <-> post-op AF incidence

- post-op AF 26.3% in metformin vs. 30.7% in non-metformin(p = 0.46)

Prior use of metformin in DM patients undergoing cardiac surgery was not associated with decreased post-op AF

[69]