Objective To investigate the diagnostic efficiency of portable handheld 12-lead electrocardiogram signal acquisition device (PH-ECG) in elderly patients with cardiovascular diseases. Methods A total of 315 elderly outpatients and inpatients diagnosed with cardiovascular diseases such as myocardial infarction and atrial fibrillation (AF) in the Department of Cardiology, Second Medical Center of Chinese PLA General Hospital from February 2020 to December 2022 were recruited in this study. All of them received conventional 12-lead electrocardiography (CL-ECG) and PH-ECG respectively. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of PH-ECG with different cardiovascular diseases were calculated. SPSS statistics 26.0 was used to perform the statistical analysis. Chi-square test was employed for intergroup comparison on enumerate data. The consistency of obtained results was tested by Kappa and paired Chi-square test. Results The sensitivity, specificity and accuracy of PH-ECG in detecting ST segment changes were 75.0%, 98.6% and 97.1%, respectively, and the Kappa value was 0.754, P=0.000 for consistency when compared with CL-ECG. In detecting abnormal T wave, the sensitivity, specificity and accuracy were 75.0%, 97.9% and 95.6% respectively in PH-ECG, and the Kappa value was 0.750 when compared with CL-ECG. For detecting atrial fibrillation, the sensitivity, specificity and accuracy were 95.5%, 99.1% and 98.1% respectively, and the Kappa value was 0.949, P=0.000. The sensitivity and specificity for the detection of myocardial infarction, premature ventricular contraction and other cardiovascular diseases were all above 90%, and there was good consistency (Kappa values >0.800) between PH-ECG and CL-ECG. Conclusion PH-ECG has the advantages of portability, real-time performance and easy operation, and has an important prospect in out-of-hospital electrocardiogram examination.