Telemedicine use increased dramatically during the COVID-19 pandemic; however, questions remain as to how telemedicine use impacts care. The purpose of this study was to examine the association of increased telemedicine use on rates of timely follow-up and unplanned readmission after acute cardiovascular hospital encounters. We examined hospital encounters for acute coronary syndrome, arrhythmia disorders, heart failure (HF), and valvular heart disease from a large U.S., multisite, integrated academic health system among patients with established cardiovascular care within the system. We evaluated 14-day postdischarge follow-up and 30-day all-cause unplanned readmission rates for encounters from the pandemic “steady state” period from May 24, 2020 through December 31, 2020, when telemedicine use was high and compared them to those of encounters from the week-matched period in 2019 (May 26, 2019, through December 31, 2019), adjusting for patient and encounter characteristics. The study population included 6,026 hospital encounters. In the pandemic steady-state period, 40% of follow-ups after these encounters were conducted via telemedicine vs 0% during the week-matched period in 2019. Overall, 14-day follow-up rates increased from 41.7% to 44.9% (adjusted difference: +2.0 percentage points [pp], 95% CI: -1.1 to +5.1 pp, P = 0.20). HF encounters experienced the largest improvement from 50.1% to 55.5% (adjusted difference: +6.5 pp, 95% CI: +0.5 to +12.4 pp, P = 0.03). Overall 30-day all-cause unplanned readmission rates fell slightly, from 18.3% to 16.9% (adjusted difference -1.6 pp; 95% CI: -4.0 to +0.8 pp, P = 0.20). Increased telemedicine use during the COVID-19 pandemic was associated with earlier follow-ups, particularly after HF encounters. Readmission rates did not increase, suggesting that the shift to telemedicine did not compromise care quality.