Baseline Cardiovascular Disease and Immune Checkpoint Inhibitor Toxicity Clustered Early and Often
Pre-existing cardiovascular disease sharply separated risk in a multicenter cohort of adults treated with immune checkpoint inhibitors. Among 608 patients who received at least one ICI dose between January 2017 and January 2023 at two tertiary hospitals in Saudi Arabia, 54 entered treatment with documented cardiovascular disease already in place. Those patients were older and carried a heavier burden of comorbidity before immunotherapy began, a profile that matters because checkpoint blockade is delivered into a host already primed for vascular and myocardial stress. During follow-up, 69 patients experienced at least one cardiovascular event, and the imbalance between groups was striking: 27 of 54 patients with baseline CVD versus 42 of 554 without baseline CVD, a difference large enough to remain obvious even before adjustment.
The signal did not depend on a single fragile modeling choice. Baseline CVD remained independently associated with cardiovascular events after multivariable adjustment, with an adjusted odds ratio of 9.46 and a 95% confidence interval from 4.92 to 18.17. Age also carried independent weight, rising by 4% per year in the adjusted model. When the analysis was tightened further to account for hypertension, diabetes mellitus, chronic kidney disease, and dyslipidemia, the association persisted with an adjusted odds ratio of 6.64. Those estimates point to a population in which pre-existing vascular injury, myocardial dysfunction, or both likely lowered the threshold for decompensation once cancer therapy began.
Cardiovascular events were mostly ischemic or heart failure-related. Myocarditis, the toxicity that often dominates discussions of immune checkpoint inhibitors, appeared only once in the entire cohort.
Ischemia and Heart Failure Outweighed Myocarditis in This Real-World Cohort
That pattern should shape bedside thinking. Immune checkpoint inhibitors are widely recognized for rare but severe immune-mediated myocarditis, yet the larger day-to-day burden in this cohort came from ischemic events and heart failure, not fulminant inflammatory myocarditis. In patients with prior coronary disease, peripheral atherosclerosis, structural heart disease, or chronic ventricular dysfunction, even modest physiologic stress can expose reserve that is already thin. Cancer therapy then layers on additional risk through inflammation, hemodynamic strain, anemia, endothelial dysfunction, and the general catabolic burden of advanced malignancy.
Because the study was observational, the results do not prove that ICIs caused the events or worsened underlying disease. Even so, the clinical pattern is difficult to ignore. A patient starting immunotherapy with prior CVD appears to represent a distinctly vulnerable subgroup, one in whom the usual oncology focus on tumor response needs to be paired with cardiovascular surveillance from the start rather than after symptoms appear. In practical terms, the findings support a cardio-oncology approach that treats baseline CVD as a risk marker, not a historical footnote.
Mortality and Survival Favored the Group Without Prior Cardiovascular Disease
All-cause mortality was also higher among patients with baseline CVD, reaching 64.8% compared with 46.4% in those without prior cardiovascular disease. Median overall survival was shorter as well: 11.5 months versus 23.8 months, with an unadjusted log-rank p value of 0.022. The survival analysis was not adjusted, so it cannot cleanly separate the contribution of cardiovascular illness from cancer burden, age, or other baseline differences. Still, the direction of effect matches the event data and suggests that pre-existing cardiovascular disease tracks with a more fragile clinical course during ICI treatment.
A single sentence captures the practical consequence: prior cardiovascular disease identified a subgroup with far more cardiac events and worse unadjusted survival.
The survival difference may reflect more than cardiac vulnerability alone. Patients with established cardiovascular disease often arrive with a narrower physiologic margin, more medications, more systemic inflammation, and more competing risks for hospitalization, treatment interruption, and death. In a cancer population, those factors can alter the ability to stay on therapy long enough to receive full benefit, and they may also magnify the impact of complications that would be survivable in a healthier host.
What the Cohort Does and Does Not Prove About Cardio-Oncology Risk
The study’s value lies in its real-world setting. Tertiary centers in Saudi Arabia provided a multicenter cohort drawn from routine practice rather than a trial population selected for cardiac fitness, which makes the findings clinically familiar to oncologists and cardiologists who care for older, comorbid patients. The analysis also used sensitivity testing with additional cardiovascular risk factors, strengthening confidence that the association was not explained away by traditional risk burdens alone.
Still, the boundaries are clear. There was no non-ICI comparator group, so the analysis cannot isolate the incremental effect of checkpoint therapy from the cardiovascular risk that already traveled with cancer, age, and comorbidity. Baseline CVD was defined by documentation before ICI initiation, but the article does not allow a finer separation of coronary disease, heart failure, arrhythmia, or cerebrovascular disease within the reported summary. Unadjusted survival data also leave residual confounding unresolved. Those limitations do not erase the signal; they define the level of certainty with which it should be used.
Why Baseline Cardiac Assessment Should Precede Checkpoint Therapy
The biology behind the association is plausible even without a causal proof. Checkpoint inhibitors can alter immune balance, and the myocardium and vasculature may become collateral targets in susceptible patients. A person with pre-existing atherosclerosis, prior infarction, ventricular dysfunction, or endothelial injury may have less reserve to absorb inflammatory or ischemic stress. In that setting, a therapy that unleashes antitumor immunity can also unmask cardiovascular instability that was already present but clinically quieter.
The most actionable message is straightforward: baseline cardiovascular disease should prompt a structured pre-treatment review before immune checkpoint therapy begins. That review should not be limited to a checklist item in the chart. It should trigger closer monitoring for ischemia, decompensated heart failure, and other cardiovascular events during treatment, especially in older patients and those carrying multiple comorbidities. Cardio-oncology collaboration is not an abstract ideal here; it is the most direct way to identify who may be entering immunotherapy with the least physiologic reserve.
The next question for this field is not whether cardiovascular disease matters, but how much of the excess risk can be reduced with proactive surveillance, optimization of cardiac therapy, and better selection of patients before the first dose is given.