A 55-year-old man from Delhi undergoes screening for coronary artery disease (CAD) using an exercise stress test (EST). He has no symptoms but multiple risk factors (hypertension, dyslipidemia, smoking history). The EST shows 2 mm ST depression in leads II, III, aVF. In this asymptomatic screening population, the prevalence of significant CAD is 10%. The EST has a sensitivity of 68% and specificity of 77% for significant CAD. Calculate the negative predictive value (NPV) and interpret what a negative EST would mean for this patient.