First-in-Human Study Using the SiroMax™ Sirolimus-Coated Balloon Catheter as a Percutaneous Transluminal Coronary Angioplasty (PTCA) Balloon Catheter to Treat Subjects Who Have Coronary Artery Disease (CAD) Involving In-Stent Restenosis (ISR) or an Unstented Lesion in a Small Coronary Vessel (DNSV).

Inclusion Criteria: * Age ≥ 21 years * Provided written informed consent * If a woman of child-bearing potential, agrees to use a reliable method of contraception from the time of screening through 12 months after the index procedure * Diagnosed with symptomatic ischemic heart disease, stable or unstable angina with signs of ischemia, silent ischemia, or a positive function test * Eligible for percutaneous coronary intervention (PCI) * Able to tolerate dual antiplatelet therapy with aspirin, plus either Clopidogrel, Prasugrel, or Ticagrelor * Any non-target lesions to be treated during the index procedure have been successfully treated * Meets the additional Inclusion criteria for the corresponding arm * Target lesion \> 50% and \< 100% stenosed by QCA in symptomatic patients, and \> 70% and \< 100% stenosed in asymptomatic patients prior to lesion pre-treatment * Distal TIMI grade flow of 3 * Target lesion must be ≤ 26mm length * Successful pre-treatment of the target lesion * Target lesion is within a native coronary artery or major branch * Inclusion Criteria (Additional for ISR arm): * Reference vessel diameter is ≥ 2.0 mm and ≤ 4.0 mm * Restenosis of stented coronary artery (Includes BMS and DES). The target lesion may have been treated with no more than 2 stents * Target lesion is within a previously placed BMS or DES and does not extend further than 5 mm beyond either the proximal or distal edge of the stent * Confirmed stent expansion ≥ 80% of distal reference vessel diameter by angiography and there is no malposed stent struts * Inclusion Criteria (Additional for PK Sub-Study): * Eligible for treatment in the ISR arm with one of the ten largest device sizes * Inclusion Criteria (Additional for DNSV arm): * Reference vessel diameter is ≥ 2.0 mm and ≤ 2.75 mm Exclusion Criteria: * Pregnant or nursing patients * Subject presents with NSTEMI and rising biomarkers, or ongoing chest pain or is hemodynamically unstable * Subject with history of ST-elevation myocardial infarction (STEMI) within 30 days of the index procedure * Subject with planned major surgery within 30 days following the index procedure * Subject with planned treatment of lesion involving aorto-ostial location * History of previous target vessel perforation * Cardiogenic shock * Patients with lesions requiring interventional treatment in more than two vessels * Extensive peripheral vascular disease that precludes safe sheath insertion * Ostial lesion or planned future treatments * Diffuse disease distal to target lesion with impaired runoff * Subject is considered not able to tolerate at least 30 seconds of coronary occlusion for the target lesion treated * Previous PCI of target vessel within 6 months prior to the procedure * Planned PCI of any vessel within 30 days post index procedure and/or planned PCI of the target vessel within 12 months post procedure * Currently participating or planning to participate, within 24 months of the index procedure, in an investigational drug or device trial * Patient is a recipient of a heart transplant * Known hypersensitivity or contraindication to aspirin, heparin, bivalirudin, or contrast agent * History of allergic reaction or sensitivity to sirolimus or other analogue or derivative * Known hypersensitivity to excipients with phospholipid or related origins and Poly(lactic-co-glycolic acid) (PLGA) * Platelet count \<100,000 cells/mm3 or \>700,000 cells/mm3 or a white blood cell count of \<3,000 cells/mm3 * Known renal insufficiency (e.g. serum creatinine \>2.5mg/dL, or creatinine clearance ≤30 mL/min), or subject on dialysis, or acute kidney failure confirmed by 50% increase of serum creatinine within 48 hours before procedure and/or decrease in urine output * Subject with history of New York Heart Association (NYHA) class III or IV heart failure * History of bleeding diathesis, active peptic ulcer or GI bleeding within prior 6 months or coagulopathy or will refuse blood transfusions * Planned surgery that would cause interruption in recommended DAPT duration per current guidelines * History of a stroke within 6 months prior to the index procedure * Concurrent life conditions with a life expectancy of less than 24 months * In Investigator's opinion, the patient is not a good candidate for the study * Left ventricular ejection fraction \< 30% * Unprotected left main coronary artery disease with ≥ 50% stenosis * Target lesion at a bifurcation Note: A target lesion near a bifurcation is allowed if only a single vessel (either main vessel or side branch) is to be treated * Evidence of extensive thrombus or dissection in target lesion * Chronic total occlusion (CTO) in target lesion * \>30% residual stenosis after pre-treatment of target lesion * Target lesion is located in the left main or within any arterial or venous graft * Target lesion is in a side branch that is "jailed" by a main vessel stent * \> 50% stenosis of an additional proximal lesion or clinically significant distal lesion (in a vessel \>2.0mm RVD) to the target or non-target lesion * Target vessel is excessively tortuous, defined as more than one bend \> 90° to reach target lesion * Exclusion Criteria (Additional for ISR arm): * Target lesion is the 3rd or greater stent failure (i.e., more than two \[2\] layers of stent are present at any segment of the target lesion) * Target vessel had any previous vascular brachytherapy treatment or is planned to undergo brachytherapy at index procedure * If single-layer ISR, any previous treatment (other than balloon angioplasty alone) of the target vessel for restenosis If double-layer ISR, any treatment (other than balloon angioplasty alone) of the double-layer ISR restenosis * Exclusion Criteria (Additional for PK Sub-Study): * Any limus family (Zotarolimus, Everolimus, Sirolimus etc.) eluting device has been placed/used in any part of the body within 3 months prior to the index procedure including any non-target lesion treated during the index procedure * The subject is taking or has taken within the last 3 months any limus family medication(s) for any reason * Subject is taking strong CYP3A4 Inhibitors within 14 days before the index procedure or plans to take the strong inhibitors during the study period (Strong inhibitors include: cobicistat; ritonavir; indinavir and ritonavir; itraconazole; ketoconazole; lopinavir and ritonavir; paritaprevir and ritonavir and ombitasvir (and/or dasabuvir); posaconazole; saquinavir and ritonavir; tipranavir and ritonavir; elvitegravir and ritonavir; telithromycin; voriconazole; ceritinib; clarithromycin; idealalisib; nefazodone; nelfinavir) * Subject is taking strong CYP3A4 Inducers within 14 days before the index procedure or plans to take the strong inducers during the study period (Strong inducers include apalutamide; carbamazepine; enzalutamide; ivosidenib; lumacaftor and ivacaftor; mitotane; phenytoin; rifampin; St. John's wort) * Exclusion Criteria (Additional for DNSV arm): * Type C lesion * Calcified or angular target lesion which cannot be pre-dilated with high pressure balloons, scoring balloon or IVL * In-stent restenosis