Yes. Diltiazem interacts with Ranexa (ranolazine) in the liver and increases its level in the blood stream. Can prolong qt and cause rythm disturbances. Other side effects from renexa likely: constipation, dizziness, headache, nausea., palpitations, dizziness and blurred vision. These are more likely with this combination, but many people on this combination of drugs. Double check with your doctor.
Here's a link... Consider checking this: http://www.drugs.com/drug_interactions.php.
Always good to check. You can use a drug interaction checker whenever you have questions about drug-drug interactions or drug - food interactions. Here is 1 option (Drugs.Com): https://www.drugs.com/drug_interactions.php Your pharmacist is also a good source of info.