Background: COVID-19 patients with any pre-existing major cardio-vascular disease (CVD) are at the highest risk of viral infection and of developing severe disease. The pathophysiological mechanism is characterized by the viral link to angiotensin-converting enzyme 2 (ACE2) and the involvement of the endothelial system with the release of cytokines and the inflicting of direct damage to the myocardium, the induction of microthrombosis, and the initiation of alterations in oxygen diffusion. The aim of the study is to analyze the clinical course and outcomes in patients (gender-stratified) with pre-existing major CVD. Methods: Out of the 1833 (973 M/860 F) patients admitted to the Internal Medicine COVID-19 Unit of “Castelli Hospital”, Lazio, Italy, from 1 January 2021 to 31 December 2021, 600 patients (320 M/280 F) with a mean age of 77 (78.6 M/75.1 F) previously had CVD. Demographic characteristics, length of the stay (LOS) and oxygen therapy were evaluated. Results: All of the CVD COVID-19 patients underwent non-invasive ventilation (NIV). CVD was linked with increased LOS (21 days F/22 M) compared to no CVD (19 days). In total, 32.7% of total patients had major CVD. Conclusions: Timely identification and evaluation of patients with pre-existing major CVD are fundamental for adequate treatment based on gender, severity, state of illness and for risk reduction.