Prinzmetal's Angina (Vasospastic Angina)
A Prinzmetal's angina attack can degenerate into a myocardial infarction, ventricular fibrillation, or complete atrioventricular block if the spasm is prolonged or occurs on an atherosclerotic lesion. Immediately call 911.
Signs requiring immediate emergency consultation: intense chest pain lasting more than 15 to 20 minutes, radiating to the left arm, jaw, or back, rapid palpitations, brief loss of consciousness or syncope, sudden shortness of breath, cold sweats, feeling of impending death. These manifestations may indicate a myocardial infarction or a serious ventricular arrhythmia in the context of prolonged coronary spasm.
Pathophysiology
Coronary spasm, which causes Prinzmetal's angina, results from hyperreactivity of the coronary vascular wall to various vasoconstrictor stimuli. Several mechanisms are involved, often interacting, in the context of pre-existing endothelial dysfunction.
| Mechanism | Description |
|---|---|
| Endothelial dysfunction | Reduction of nitric oxide (NO) and prostacyclin production, protective vasodilatory molecules; favored by smoking, subclinical atherosclerosis, oxidative stress, and inflammatory factors |
| Vascular smooth muscle hyperreactivity | Increased sensitivity to endogenous vasoconstrictors (endothelin-1, angiotensin II, thromboxane A2, serotonin); intrinsic abnormality of coronary smooth muscle cell contractility |
| Autonomic nervous system hyperactivity | Nocturnal and early morning vagal predominance, increased vasoconstrictor alpha-adrenergic tone; explain the circadian rhythm characteristic of the seizures |
| Local vascular inflammation | Infiltration of mast cells and macrophages into the coronary wall; local release of vasoconstricting and pro-inflammatory mediators |
| Magnesium deficiency | Hypomagnesemia associated with vascular smooth muscle hyperexcitability; facilitating role documented in some series |
| Coronary atherosclerosis associated | Present in 30 to 50% of cases; non-obstructive plaques that impair the local vasomotor response and are sites prone to spasm |
Triggering and risk factors
Identifying triggers is essential for relapse prevention. Some are preventable, and their elimination is a fundamental therapeutic component.
- Active smoking: a major and independent risk factor, nicotine causes direct coronary vasoconstriction and worsens endothelial dysfunction; smoking cessation significantly reduces the frequency of attacks
- Exposure to intense cold: cold causes sympathetic activation and reflex peripheral and coronary vasoconstriction, particularly relevant in the Quebec climate context
- Acute emotional stress: catecholamine release promoting vasospasm via alpha-adrenergic receptors
- Hyperventilation: respiratory alkalosis inducing coronary vasoconstriction
- Vasoconstrictor medications: triptans (migraine treatment), ergotamine and ergot derivatives, cocaine and amphetamines, certain chemotherapy drugs (5-fluorouracil, bevacizumab), sympathomimetic nasal decongestants
- Non-selective beta-blockers: by blocking the vasodilating beta-2 receptors, they can promote a vasoconstrictive alpha-adrenergic predominance
- Alcohol: Excessive alcohol consumption and alcohol withdrawal are recognized triggers
- East Asian origin: significantly higher prevalence in Japan, Korea, and China, likely related to genetic factors of coronary vascular reactivity
Clinical manifestations
The clinical presentation of Prinzmetal angina is characteristic enough to guide the diagnosis even before paraclinical confirmation. Knowledge of its temporal profile and distinctive semiological features is essential to avoid diagnostic delay.
| Characteristic | Typical description | Specifics regarding stable angina |
|---|---|---|
| Occurrence | Mainly at rest, at night (between midnight and 8 AM) or upon waking | Stable angina: occurs with exertion, never at rest in pure forms |
| Chest pain | Constrictive or vice-like, retrosternal, radiating to the left arm, jaw, shoulder, or back; often severe intensity | Similar semiology but with a different triggering context |
| Duration of the crisis | A few minutes to 20 to 30 minutes as a rule; spontaneous resolution with relief of spasm | Stable angina: subsides in less than 5 minutes upon cessation of exertion |
| Response to nitroglycerin | Rapid and complete relief with sublingual nitroglycerin within minutes | Similar to stable angina; response often even faster in Prinzmetal |
| Associated symptoms | Possible palpitations, bradycardia, syncope, or presyncope in case of arrhythmia associated with spasm | Ventricular arrhythmias are more frequent than in classic stable angina. |
| Exercise tolerance | Often normal between episodes; some patients can perform vigorous exercise without symptoms | Absence of limitation of effort, unlike stable angina |
| Cyclical evolution | Crises often grouped into clusters over several days or weeks, alternating with periods of prolonged spontaneous remission | Characteristic of vasospastic angina, absent in stable angina |
Diagnosis
The diagnosis of Prinzmetal angina is based on a combination of clinical and electrocardiographic findings, and when necessary, on pharmacological provocation of spasm during coronary angiography. The difficulty lies in the fact that most tests are performed outside of episodes, a period during which the results can be strictly normal.
| Review | Expected results | Diagnostic value |
|---|---|---|
| ECG during the crisis | Transient ST-segment elevation (ST elevation), often marked and diffuse in the ischemic territory; possible transient left bundle branch block or ventricular arrhythmias (PVCs, VT, VF) | Highly diagnostic if captured; complete normalization at the end of the crisis |
| ECG outside of crisis | Often strictly normal; sometimes negative or inverted T waves in the affected territory in frequent severe forms | Low diagnostic value outside of a crisis; does not rule out the diagnosis |
| Holter ECG 24 to 48 hours | Recording of nighttime or spontaneous ST changes; arrhythmias concurrent with ischemic episodes | Excellent choice for documenting ambulatory crises; positive if an episode occurs during recording |
| Cardiac troponins | Normal in brief crises; may rise moderately in case of prolonged spasm with minimal myocardial necrosis | Useful for assessing the severity of ischemia and ruling out STEMI if positive |
| Coronary angiography | Coronary arteries that appear normal on angiography (50–70% of cases) or non-obstructive atherosclerotic lesions; provocation test with methylergonovine or acetylcholine to induce spasm | Diagnostic reference; pharmacological provocation test confirms spasm by reproducing symptoms with ST elevation and relief with intracoronary nitroglycerin. |
| Stress test | Often normal or minimally contributory (unlike stable angina); can sometimes trigger paradoxical spasm | Useful for excluding a component of associated exertional angina; does not confirm Prinzmetal. |
| Echocardiogram | Normal at rest between episodes; may show segmental abnormalities of ventricular kinetics during an acute episode | Useful for assessing left ventricular function and ruling out other causes of chest pain |
Differential diagnosis
The clinical presentation of Prinzmetal angina can mimic several cardiovascular and non-cardiovascular conditions. The distinction is critical because treatments differ, and some therapeutic errors can worsen the spasm.
| Affection | Distinctive elements |
|---|---|
| Acute Coronary Syndrome (STEMI / NSTEMI) | Persistent ST-segment elevation (non-transient), significantly elevated troponins, coronary angiography showing a thrombotic occlusion; in Prinzmetal's angina, ST elevation is transient and arteries are often normal |
| Stable exertional angina | Occurs exclusively with exertion or stress, ST depression (not ST elevation), obstructive coronary stenoses on coronary angiography; normal exercise tolerance absent |
| Takotsubo syndrome (stress cardiomyopathy) | Triggered by intense emotional stress, apical akinesia characteristic on echocardiography, normal coronary angiography, complete spontaneous resolution in weeks; mainly affects menopausal women |
| Pulmonary embolism | Predominant dyspnea, pleuritic chest pain, hypoxemia, signs of acute cor pulmonale on ECG (right axis deviation, right bundle branch block); confirmatory chest CT angiogram |
| Acute pericarditis | Slightly elevated ST-segment depression, concave upward, no reciprocal changes, pericardial friction rub, pain worsened by lying down and relieved by leaning forward; slightly elevated troponins. |
| Severe gastroesophageal reflux | Nocturnal retrosternal chest pain possibly mimicking coronary pain; absence of ECG changes, relieved by antacids, associated with heartburn |
Treatment
The management of Prinzmetal's angina rests on two complementary pillars: the management of acute crises and the prevention of long-term recurrences. The identification and suppression of triggering factors are as important as pharmacological treatment.
| Treatment | Terms | Remarks |
|---|---|---|
| Sublingual nitroglycerin (acute attack) | 0.4 mg sublingually, repeatable every 5 minutes up to 3 doses; emergency transport if no response after 15 minutes | Standard treatment for a crisis: quickly relieves spasm through direct vasodilation of the coronary wall; to be carried on one's person at all times |
| Calcium channel blockers (maintenance therapy) | Amlodipine 5 to 10 mg/day, diltiazem 180 to 360 mg/day (extended-release forms), verapamil 240 to 480 mg/day (extended-release forms); to be preferred as monotherapy or in combination. | First-line treatment for preventing recurrence; reduces vasoconstriction of the coronary smooth muscle; proven effective in 90% of cases; should be continued long-term |
| Long-acting nitrate derivatives (maintenance treatment) | Isosorbide mononitrate 20 to 60 mg/day or transdermal nitroglycerin patch with a nitrate-free interval of 8 to 12 hours to avoid tolerance | Associated with calcium channel blockers in refractory or severe forms; the nitrate-free interval is mandatory to maintain efficacy |
| Absolute smoking cessation | Therapeutic support, nicotine replacement therapy, varenicline (Chantix) or bupropion depending on the patient's profile | The most effective intervention on the natural history of the disease; tobacco perpetuates endothelial dysfunction and vasospastic reactivity |
| Removal of triggering factors | Discontinuation of triptans, ergotamine, cocaine, sympathomimetic decongestants; adaptation of clothing and behavior to the cold | Immediate reduction in seizure frequency in many cases; essential before any pharmacological escalation |
| Beta-blockers | To be avoided in general in pure Prinzmetal angina | Risk of promoting vasospasm by unmasking the vasoconstrictor alpha-adrenergic effect; can be used cautiously if an associated component of effort angina is documented |
| Implantable Automatic Defibrillator (IAD) | Indicated in cases of a history of resuscitated sudden cardiac death or documented ventricular fibrillation related to coronary spasm | Reserved for high-risk arrhythmic forms; does not suppress spasm but prevents sudden death from malignant arrhythmia |
| Magnesium Supplementation | Oral magnesium (200 to 400 mg/day) in case of documented hypomagnesemia or in refractory forms | Documented benefit in some studies; few adverse effects; can be used in conjunction with conventional treatment |
Prognosis and evolution
Prinzmetal's angina has a variable prognosis depending on the severity of the episodes, the presence or absence of associated coronary atherosclerosis, and the quality of therapeutic control. With appropriate treatment and elimination of triggering factors, the outcome is generally favorable.
- Complete or near-complete remission with calcium channel blockers in 70 to 90% of cases with regular follow-up and adherence to preventive measures
- The risk of sudden death due to ventricular fibrillation is estimated at 1 to 2 per 100,000 people per year in severe, uncontrolled cases, primarily in cases of multivessel spasm or prolonged spasm
- Possible myocardial infarction in case of prolonged spasm (more than 30 to 45 minutes) not relieved by trinitrin, particularly in patients with associated coronary atherosclerosis.
- Evolution by clusters (periods of frequent crises alternating with spontaneous remissions of several weeks to months) characteristic of the natural history of the disease
- Poor prognostic factors: persistent smoking, multivessel spasm, associated obstructive coronary atherosclerosis, documented ventricular arrhythmias, poor therapeutic compliance
- Complete smoking cessation associated with a significant reduction in crises and an improvement in long-term prognosis, constituting the most impactful individual intervention
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Clinique Omicron welcomes patients at its Quebec locations for any questions regarding their cardiovascular health. Our physicians provide the initial clinical assessment, prescribe appropriate complementary examinations, and refer to relevant cardiologists when the situation requires. Book an appointment at the clinic nearest to you.
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