Acute pulmonary embolism (PE) is the third cause of cardiovascular (CV) mortality. We evaluated a new risk index, named Age-Mean Arterial Pressure Index (AMAPI), to predict 30-day CV mortality in patients with acute PE. Data of 209 patients (44.0% male and 56.0% female, mean age 70.58 ± 14.14 years) with confirmed acute PE were retrospectively analysed. AMAPI was calculated as the ratio between age and mean arterial pressure (MAP), which was defined as [systolic blood pressure + (2 × diastolic blood pressure)]/3. To test AMAPI accuracy, a comparison with shock index (SI) and simplified pulmonary embolism severity index (sPESI) was performed. Patients were divided in two groups according their hemodynamic stability, or not, at admission. 30-day mortality rate, in all cases for CV events, was 10.5% (n = 22). Hemodynamically unstable patients had a higher AMAPI compare to those without hypotension at admission (1.28 ± 0.39 vs 0.78 ± 0.27, p < 0.0001). Receiving operative curve analyses (ROC) found the optimal cut-off for AMAPI in hemodynamically stable and unstable patients ≥0.9 and ≥0.92, respectively. In both groups, patients with an AMAPI over the cut-off were significantly older, hypotensive (both systolic and diastolic blood pressure), with a higher SI and lower MAP. In hemodynamically stable patients, 30-day CV mortality risk prediction was improved adding AMAPI ≥0.9 to both SI and sPESI (net reclassification improvement—NRI—of 14.2%, p = 0.0006 and 11.5%, p = 0.0002, respectively). In hemodynamically unstable patients NRI was 19.2%, p = 0.006. Mantel–Cox analysis revealed a statistical significant difference in the distribution of survival between hemodynamically stable patients with an AMAPI index ≥0.9 compared to those with an AMAPI <0.89 [log rank (Mantel–Cox) p < 0.0001] and in hemodynamically unstable patients with an AMAPI ≥0.92 [log rank (Mantel–Cox) p = 0.001]. AMAPI ≥0.90 and ≥0.92 predict 30-day CV mortality in hemodynamically stable and unstable patients with acute PE.