Discoloration of toes

65 y, white man, with h/o CAD and tobacco dependence, presents to the ER with dyspnea and angina. He is compliant with his medication regimen, which includes ASA, Enalapril, Metoprolol and Lovastatin. On exam, his vital signs were stable and no cardio-pulmonary abnormalities were noted. Extremities show brownish-black discoloration of his toes, with evidence of dry gangrene. Peripheral lower extremity pulses are absent. On further questioning, he mentions developing the discoloration 2 years ago. Which of the following historical clue is the most important in determining the likely cause of the pathology?

1. History of PTCA- CORRECT ANSWER.
2. Tobacco dependence, 3 ppd for 40 years.
3. History of Rt sided endocarditis
4. History of Frostnip 2 years ago, while on a cruise to Alaska