Unstable angina

Incidence and Predictors of Obstructive Coronary Artery Disease and the Role of Cardiac Troponin Assays in Patients with Unstable Angina

In a time when cardiac troponin assays are widely used to detect myocardial injury, data remain scarce concerning the incidence and predictors of substantial obstructive coronary artery disease that causes unstable angina. This retrospective single-center study included consecutive patients hospitalized for unstable angina from January 2015 through January 2016. Patients with troponin I levels above the upper reference limit and those who did not undergo angiography were excluded. Multivariate logistic regression analysis was used to identify predictors of obstructive coronary artery disease that warranted revascularization and of major adverse cardiac events up to 6 months after discharge from the hospital. Of the 114 patients who met the inclusion criteria, 46 (40%) had obstructive coronary artery disease. In the univariate analysis, male sex, white race, history of coronary artery disease, prior revascularization, hyperlipidemia, chronic kidney disease, aspirin use, long-acting nitrate use, and Thrombolysis in Myocardial Infarction score ≥3 were associated with obstructive coronary artery disease. History of coronary artery disease, prior revascularization, hyperlipidemia, and long-acting nitrate use were associated with major adverse cardiac events. Male sex was an independent predictor of obstructive coronary artery disease (adjusted odds ratio=4.82; 95% CI, 1.79-13; P=0.002) in the multivariate analysis. Our results showed that coronary artery disease warranting revascularization is present in a considerable proportion of patients who have unstable angina. The association that we found between male sex and obstructive coronary artery disease suggests that the risk stratification of patients presenting with unstable angina may need to be refined to improve outcomes.

Pharmacotherapy of unstable angina

All patients with unstable angina should be admitted to a coronary or an intensive care unit. There should be an attempt to classify the patient according to the proposed Braunwald nomenclature. If the patient has a secondary cause for unstable angina (e.g., tachyarrhythmia, heart failure, fever, thyrotoxicosis, severe hypertension, hypoxia, unusual emotional stress, or anemia), this condition should be treated initially with therapy specific for that etiology. If the patient does not have a secondary etiology, therapy should be initiated with nitrates, preferably intravenous nitroglycerin. Heparin should be concomitantly administered. If the patient cannot receive heparin, aspirin should be initiated. All patients should receive beta-blockers. If the patient cannot take a beta-blocker, a calcium antagonist (probably diltiazem) should be initiated. However, if the patient is refractory to beta-blockers, the dihydropyridine nifedipine should be added. Failure to all pharmacologic interventions necessitates a progressive invasive approach dictated by the potential surgical risk of the patient. Long-term aspirin and beta-blockers should be strongly considered.

Higher recurrence rate after coronary angioplasty in unstable angina pectoris

PURPOSE

Recurrent stenosis after percutaneous transluminal coronary angioplasty (PTCA) is a significant problem, requiring repeat dilation in about one-third of all treated patients. Various clinical and procedure-related predictors have been proposed. Between 1983 and 1987, 257 patients underwent 322 procedures, where 380 stenoses were attempted. Indications were: stable angina pectoris 73%, unstable angina pectoris 22%, other indication 5%. The primary success rate was defined as a less than 50% remaining postprocedure stenosis.

FINDINGS

Repeat angiograms were done for 88% of the initially successful cases, either six months after PTCA or if there was a clinical recurrence. Restenosis was defined as a recurrence of a more than 50% diameter stenosis. The restenosis rate was 33% and was significantly higher (p less than 0.05) for unstable (46%) than for stable angina pectoris (29%). There was a nonsignificant tendency to a higher restenosis rate in the left anterior descending artery than in the other coronary vessels.

IMPLICATIONS

The increased restenosis rate seen after PTCA for unstable angina pectoris could be caused by a higher activity in systems affecting the proliferative processes in the smooth muscle cells of the arterial wall, which is thought to form the pathophysiologic basis for restenosis after PTCA.