Objective To investigate the effect of extended nursing on medication compliance in patients with coronary heart disease after percutaneous coronary stent implantation. Methods Clinical data were collected from 70 patients with coronary heart disease who received percutaneous coronary intervention in our hospital from January, 2019 to December 2020, and the patients were divided into experimental group and control group using a random number table, with 35 patients in each group. The patients in the control group were given routine nursing and discharge guidance, and those in the experimental group were given extended nursing in addition to the nursing in the control group. The two groups were compared in terms of psychological state, medication compliance, and adverse cardiovascular events. Results Compared with the control group, the experimental group had significantly lower scores of anxiety (27.25±5.21 vs 36.52±4.61, t=7.8833, P<0.05) and depression (28.14±6.07 vs 38.76±8.47, t=6.0294, P<0.05). The experimental group had a significantly higher medication compliance rate than the control group (94.29% vs 77.14%, χ2=4.2000, P<0.05). The experimental group had a significantly lower incidence rate of adverse cardiovascular events (such as arrhythmia, myocardial ischemia, and thrombosis) than the control group (5.71% vs 25.71%, χ2 = 5.2851, P <0.05). Conclusion The application of extended nursing in patients with coronary heart disease after PCI can improve patients' bad psychological states and medication compliance after discharge and effectively reduce the rate of adverse cardiovascular events.