Which of the following conditions prevents certification for a driver with coronary heart disease?

Sustained ventricular tachycardia is a serious condition characterized by a rapid heartbeat that can be dangerous and lead to more severe complications, including the potential for sudden cardiac events. In the context of FMCSA guidelines for driver certification, this condition is a disqualifying factor for commercial drivers because it raises significant safety concerns. The stability of cardiac health is critical for individuals who operate large vehicles, as any sudden episodes of rapid heart rate could impair a driver’s ability to control the vehicle properly, posing risks not only to themselves but also to others on the road.

The other conditions listed, while they might have implications for a driver's overall health, do not automatically prevent certification. A history of hypertension can often be managed with appropriate treatment and monitoring, so it does not disqualify a driver outright. Mild exercise intolerance may suggest some level of heart issue but does not necessarily impair driving capabilities to the extent required for disqualification. Prior heart surgery also does not directly disqualify an individual if they can demonstrate recovery and stability as determined by a thorough medical evaluation. Therefore, sustained ventricular tachycardia is the most critical condition regarding disqualification for driver certification in this context.