7.2 Percutaneous Coronary Intervention: Stents, No-Reflow and Post-PCI Care
Key Takeaways
- Current-generation drug-eluting stents are standard of care with restenosis under 5%; bioresorbable scaffolds were withdrawn in 2017 for excess scaffold thrombosis and are not a correct exam answer.
- No-reflow is a microvascular problem treated with intracoronary adenosine 30-100 mcg, nicardipine 100-300 mcg, verapamil 100-200 mcg, or nitroprusside 50-200 mcg delivered distally - nitroglycerin dilates epicardial vessels and does not treat it.
- Stent thrombosis is categorized as acute (under 24 hours), subacute (24 hours to 30 days), late (30 days to 1 year), and very late (over 1 year); it presents as STEMI with 20-40% mortality, whereas restenosis presents as gradual recurrent exertional angina.
- In acute myocardial infarction complicated by cardiogenic shock, culprit-lesion-only PCI is preferred, because routine immediate multivessel PCI increased 30-day death and renal replacement therapy.
- Default DAPT after ACS is at least 12 months, but transition to ticagrelor monotherapy 1 month or more after PCI roughly halves major bleeding in patients who have tolerated dual therapy.
From Balloon to Current-Generation Stent
Test-plan item III.A.3 covers percutaneous coronary intervention (PCI) itself. Reperfusion timing for ST-elevation myocardial infarction is taught elsewhere in this guide; here the subject is the procedure, its hardware, its failures, and the post-procedure surveillance that belongs to the nurse.
| Device generation | Mechanism and limitation | Restenosis rate | Minimum DAPT |
|---|---|---|---|
| Plain balloon angioplasty (POBA) | Fractures plaque; limited by elastic recoil, negative remodeling, and abrupt closure in about 5% | 30-40% | Not stent-dependent |
| Bare-metal stent (BMS) | Scaffolds against recoil but provokes neointimal hyperplasia | 20-30% | 1 month |
| First-generation DES (sirolimus, paclitaxel) | Durable polymer suppresses neointima but delays endothelialization, causing late and very late stent thrombosis | Under 10% | 12 months historically |
| Current-generation DES (everolimus, zotarolimus on thin-strut cobalt- or platinum-chromium, biocompatible or bioabsorbable polymer) | Standard of care; rapid endothelialization with durable antiproliferative effect | Under 5% | As short as 1 month in high bleeding risk |
| Bioresorbable scaffold (BRS) | Intended to vanish and restore vasomotion; the everolimus polylactide device was withdrawn in 2017 for excess scaffold thrombosis | Higher than DES | Not standard of care |
The exam trap is treating bioresorbable scaffolds as the current best option. They are not. Current-generation drug-eluting stents are the default, and the meaningful modern decisions are about lesion preparation, imaging guidance, and antiplatelet duration - not about which scaffold vanishes.
Imaging and Physiology in the PCI Decision
Fractional flow reserve (FFR) at or below 0.80 and instantaneous wave-free ratio (iFR) at or below 0.89 define a physiologically significant lesion; those thresholds and the IVUS-versus-OCT comparison are covered in the diagnostic catheterization section. What matters here is how the data changes the intervention. Intravascular ultrasound (IVUS) or optical coherence tomography (OCT) guidance reduces target-lesion failure compared with angiography alone by sizing the vessel correctly and confirming stent expansion. Practical targets are a minimal stent area above roughly 5.5 mm2 in a non-left-main vessel and above roughly 7 mm2 in the left main. Imaging also quantifies calcium: a calcium arc exceeding 180 degrees over a segment of 5 mm or more, or calcium thicker than 0.5 mm on OCT, predicts stent underexpansion and mandates calcium modification before stenting. Underexpansion is the leading mechanical cause of both stent thrombosis and restenosis, which is why "just put a stent in it" is the wrong answer for a heavily calcified lesion.
Calcium Modification and Complex Subsets
- Rotational atherectomy uses a diamond-coated burr at 140,000-180,000 rpm to ablate calcium differentially. Nursing-relevant risks: slow flow from particulate embolization, burr entrapment, coronary perforation, and bradycardia or transient heart block, particularly in the right or dominant coronary artery - have transcutaneous pacing immediately available and expect the operator to run short ablation passes.
- Orbital atherectomy uses an eccentrically mounted diamond crown and sands bidirectionally.
- Intravascular lithotripsy delivers acoustic pressure pulses of roughly 50 atmospheres from a balloon to fracture both superficial and deep calcium. Pulses are ECG-gated, and the nurse may see paced-appearing capture beats on the monitor during delivery - a recognized, benign phenomenon.
- Bifurcation lesions are preferentially treated with a provisional single-stent strategy, reserving two-stent techniques (culotte, double-kissing crush, T-and-protrusion) for complex anatomy, and finishing with kissing-balloon inflation. Side-branch occlusion is the characteristic complication.
- Left main PCI is an accepted alternative to bypass surgery in patients with low-to-intermediate anatomic complexity; intravascular imaging is close to mandatory, and distal left main bifurcation disease is the harder subset.
- Chronic total occlusion PCI uses antegrade wire escalation, antegrade dissection re-entry, or retrograde collateral approaches. These are long cases with large contrast and radiation loads and higher perforation and donor-vessel injury risk. The accepted indication is symptom relief, not mortality reduction.
Complete Versus Culprit-Only Revascularization
In STEMI with multivessel disease and non-complex non-culprit lesions, complete revascularization - during the index procedure or as a staged procedure - reduces cardiovascular death and myocardial infarction. The exception is the exam question: in acute myocardial infarction with cardiogenic shock, routine immediate multivessel PCI increased 30-day death and renal replacement therapy compared with a culprit-lesion-only strategy. Shock changes the answer.
A patient with anterior STEMI arrives in profound cardiogenic shock on norepinephrine and dobutamine. Angiography shows a 100% proximal LAD occlusion plus 80% stenoses in the mid right coronary artery and a large obtuse marginal branch. Which revascularization strategy is supported by the evidence for this presentation?
Periprocedural Antithrombotic Therapy
Oral P2Y12 loading doses and the general antithrombotic regimen are covered in the reperfusion section; the PCI-specific points are these.
| Agent | Regimen | PCI-specific note |
|---|---|---|
| Unfractionated heparin | 70-100 units/kg bolus without a GP IIb/IIIa inhibitor; 50-70 units/kg with one | Target ACT 250-300 seconds (HemoTec) without a GP IIb/IIIa inhibitor, 200-250 seconds with one |
| Bivalirudin | 0.75 mg/kg bolus, then 1.75 mg/kg/h | Lower bleeding than heparin plus GP IIb/IIIa; continue the full-dose infusion 3-4 hours after PCI to prevent acute stent thrombosis |
| Cangrelor | 30 mcg/kg bolus, then 4 mcg/kg/min | IV P2Y12 inhibitor with onset within about 2 minutes and offset within about 60 minutes; for the P2Y12-naive patient who cannot absorb oral therapy - intubated, vomiting, in shock, or being cooled |
| GP IIb/IIIa inhibitors | Eptifibatide 180 mcg/kg bolus x2 then 2 mcg/kg/min; tirofiban 25 mcg/kg bolus then 0.15 mcg/kg/min | Reasonable as bailout for large thrombus burden, slow flow, or no-reflow; check a platelet count 2-4 hours after starting because acute profound thrombocytopenia can occur within hours |
The cangrelor sequencing rule is a favorite item: because cangrelor occupies the receptor, ticagrelor may be given at or before the end of the infusion, but clopidogrel or prasugrel must be given only after the infusion is stopped, or the thienopyridine's active metabolite has nothing to bind and the patient is left unprotected when cangrelor washes out in an hour.
Complications of PCI
Coronary dissection and acute closure. Wire or balloon trauma creates an intimal flap; extension can occlude the vessel. Presents with abrupt chest pain, ST elevation, and hemodynamic collapse on the table. Treated by stenting the dissected segment.
Coronary perforation. Graded by the Ellis classification: type I is an extraluminal crater without extravasation, type II is myocardial or pericardial blushing, and type III is frank contrast extravasation through an exit hole 1 mm or larger. Management escalates through prolonged balloon inflation proximal to the perforation, reversal of anticoagulation with protamine, deployment of a covered stent graft, coil embolization for distal wire perforations, emergent pericardiocentesis, and surgery. The nursing signal is a patient who becomes abruptly hypotensive with rising CVP, tachycardia or bradycardia, and new chest pain during or shortly after the case - assume tamponade and get an echocardiogram.
No-reflow and slow flow. The epicardial vessel is open but antegrade flow is TIMI grade 2 or less. The mechanism is microvascular, not epicardial: distal embolization of atherothrombotic debris, microvascular spasm, endothelial and myocyte swelling, ischemia-reperfusion injury, and intramyocardial hemorrhage. It is most common in STEMI with heavy thrombus burden, long ischemic times, saphenous vein graft intervention, and after atherectomy. Clinically it produces persistent ST elevation, ongoing chest pain, hypotension, and - especially in inferior infarction - bradycardia and heart block. Treatment is intracoronary vasodilators delivered distally through a microcatheter or aspiration catheter: adenosine 30-100 mcg boluses, nicardipine 100-300 mcg, verapamil 100-200 mcg, or nitroprusside 50-200 mcg, with a glycoprotein IIb/IIIa inhibitor when thrombus burden is high. Intracoronary or intravenous nitroglycerin does not treat no-reflow - it dilates epicardial conductance vessels, not the obstructed microcirculation. That distinction is heavily tested.
Side-branch occlusion during bifurcation stenting causes chest pain with regional ST change; small branches are usually managed conservatively.
Periprocedural myocardial infarction (type 4a) requires a cardiac troponin rise above 5 times the 99th percentile upper reference limit in a patient with a normal baseline, plus evidence of new ischemia - new ECG changes, an angiographic complication, or new wall motion abnormality. Type 4b is stent thrombosis and type 4c is restenosis-related infarction.
Contrast-associated acute kidney injury is a creatinine rise of 0.5 mg/dL or 25% within 48-72 hours, peaking at days 3-5. Risk rises with baseline eGFR below 60 mL/min/1.73 m2, diabetes, heart failure, hypotension, balloon pump support, and contrast volume; a contrast-volume-to-eGFR ratio above 3 is a useful bedside threshold. Prevention is isotonic saline hydration, contrast minimization, and withholding nephrotoxins. N-acetylcysteine and sodium bicarbonate are not effective and should not be recommended.
Cholesterol embolization is the great mimic. Catheter manipulation in a diseased aorta showers cholesterol crystals days to weeks after the procedure, producing livedo reticularis, blue toes with palpable pedal pulses, peripheral eosinophilia, transient hypocomplementemia, and a subacute, stepwise, often irreversible decline in renal function. Contrast nephropathy peaks at 3-5 days and recovers; atheroembolic renal failure appears later and worsens. Recognizing which one you are looking at changes the prognosis conversation entirely.
During primary PCI for an inferior STEMI with heavy thrombus burden, the operator restores a widely patent right coronary artery but antegrade flow remains TIMI grade 1. The patient has persistent ST elevation, chest pain, hypotension, and a heart rate of 42 beats per minute. Which intervention directly addresses the underlying problem?
Stent Thrombosis Versus In-Stent Restenosis
| Feature | Stent thrombosis | In-stent restenosis |
|---|---|---|
| Mechanism | Acute platelet-rich thrombus occluding the stent | Gradual neointimal hyperplasia and neoatherosclerosis narrowing the lumen |
| Timing categories | Acute (< 24 h), subacute (24 h - 30 d), late (30 d - 1 y), very late (> 1 y) | Typically 3-12 months; later with drug-eluting stents |
| Presentation | Abrupt and catastrophic - STEMI in most cases, ventricular arrhythmia, cardiac arrest; mortality 20-40% | Gradual return of exertional angina in a stable pattern; occasionally NSTEMI |
| ECG | New ST elevation in the stented territory | Often normal at rest; ischemia only with stress |
| Main drivers | Premature P2Y12 discontinuation, stent underexpansion or malapposition, residual dissection, CYP2C19 loss-of-function on clopidogrel, hypercoagulable state, bifurcation or long stents | Diabetes, small-caliber vessel, long stent length, ostial location, bare-metal stent, renal failure |
| Management | Emergent angiography with balloon or aspiration, intensified antiplatelet therapy, imaging to find the mechanical cause | Elective drug-coated balloon, repeat drug-eluting stent, brachytherapy, or bypass surgery |
| Nursing implication | Any chest pain after PCI is a re-emergency until proven otherwise | Recurrent stable angina warrants outpatient evaluation, not a code STEMI |
Post-PCI Nursing Management
Access-site care - patent hemostasis with a radial band, femoral sheath pull with an ACT below 150-180 seconds, closure-device bed-rest times, and the presentation of retroperitoneal hematoma - is covered in detail in the reperfusion and diagnostic catheterization sections. Layer these PCI-specific priorities on top:
- Obtain a post-procedure 12-lead ECG within 30-60 minutes and establish it as the new baseline. Every subsequent complaint is compared against it, not against the pre-procedure tracing.
- Reassess chest pain deliberately and repeatedly. Post-PCI discomfort is common and often musculoskeletal or from stent stretch, but new pain accompanied by ST elevation, hemodynamic change, or arrhythmia is stent thrombosis until proven otherwise. Escalate immediately rather than medicating and reassessing in 30 minutes.
- Expect reperfusion arrhythmias. Accelerated idioventricular rhythm at 60-110 beats per minute after successful reperfusion is benign and self-limited; suppressing it with an antiarrhythmic is the wrong reflex.
- Watch the right coronary patient for bradycardia and block, particularly after atherectomy or with no-reflow.
- Protect the kidneys: maintain post-procedure hydration, record hourly urine output, hold metformin for 48 hours if renal function is at risk, and recheck creatinine at 48-72 hours.
- Radial forearm compartment syndrome presents with escalating forearm pain, swelling, and paresthesia after band removal and is a surgical emergency, distinct from a simple hematoma.
DAPT Duration and the High-Bleeding-Risk Patient
The default after ACS is aspirin plus an oral P2Y12 inhibitor for at least 12 months. Current guidance also supports transitioning to ticagrelor monotherapy 1 month or more after PCI in patients who have tolerated dual therapy, which roughly halves major bleeding without increasing ischemic events. Add a proton pump inhibitor for gastrointestinal bleeding risk. In patients who also require long-term oral anticoagulation, aspirin is discontinued 1-4 weeks after PCI and the regimen continues as a P2Y12 inhibitor - preferably clopidogrel - plus the anticoagulant. Screen for high-bleeding-risk features: age above 75, prior bleeding or stroke, anemia, thrombocytopenia, dialysis or eGFR below 30, active malignancy, cirrhosis, and planned major surgery.
The One Discharge Message That Matters Most
Never stop the P2Y12 inhibitor without instruction from cardiology. Premature discontinuation is the strongest single predictor of stent thrombosis, and it is usually driven by three fixable things: cost, a bleeding scare, or a dentist or surgeon telling the patient to hold it. Send the patient out with a card documenting the stent type, location, and implant date; instruct them to show it to every clinician; confirm the prescription is filled and affordable before discharge; and teach that elective non-cardiac surgery should be deferred - at minimum 30 days and preferably 6 months after a drug-eluting stent - with any earlier procedure coordinated with the interventional cardiologist rather than the proceduralist alone.
Six days after receiving a drug-eluting stent to the LAD, a patient returns to the emergency department with crushing chest pain that began 40 minutes ago. He stopped ticagrelor four days ago because he could not afford the copay. The ECG shows 4 mm of ST elevation in V2-V4. What is the priority nursing action?