A 62-year-old woman with a 15-year history of COPD (GOLD Stage 3) and chronic cor pulmonale presents with sudden worsening of dyspnea and syncope. She has been bedridden for 3 weeks due to acute exacerbation. On examination, she is cyanotic, heart rate 125/min, blood pressure 95/60 mmHg, JVP elevated at 8 cm, and right ventricular heave is palpable. Arterial blood gas shows pH 7.28, PaCO₂ 65 mmHg, PaO₂ 48 mmHg on supplemental oxygen. Chest X-ray shows chronic hyperinflation with no new infiltrates. Troponin-I is elevated at 0.18 ng/mL (normal <0.04). What is the primary mechanism of death in this acute decompensation?