A 41-year-old female presents with recurrent episodes of severe palpitations, diaphoresis, tremor, chest tightness, and a sense of impending doom occurring 2-3 times weekly for 3 months. She was diagnosed with panic disorder by her primary care provider and started on sertraline, with no improvement after 8 weeks at therapeutic dose. On further evaluation, the PMHNP notes the episodes are not triggered by specific situations or cognitive patterns. The patient reports severe headaches accompany each episode. Her blood pressure during an in-office episode is 210/120 mmHg, and between episodes she is consistently normotensive. Which finding is most suggestive that this presentation is not primary panic disorder?