Can C reactive protein or troponins T and I predict outcome in patients with intractable unstable angina?

Troponin-positive chest pain with unobstructed coronary arteries: definitive differential diagnosis using cardiac MRI

OBJECTIVE

The purpose of this study was to assess the outcome of cardiac MRI (CMRI) with late gadolinium enhancement (LGE) at outpatient follow-up in a consecutive series of patients with troponin-positive chest pain but unobstructed coronary arteries at the index admission.

METHODS

The study group comprised 91 consecutive patients who presented to our institution with cardiac chest pain, elevated troponin I and unobstructed coronary arteries on coronary angiography. All patients underwent an outpatient CMRI with LGE imaging in order to establish a definitive diagnosis.

RESULTS

The average time from coronary angiography to LGE-CMRI was 2 months. 73% of patients had no abnormality on their LGE-CMRI, 16% of patients had patchy late enhancement consistent with myocarditis and 11% had focal subendocardial or full thickness late enhancement consistent with myocardial infarction. There were no deaths in this cohort during a mean follow-up of 21 months.

CONCLUSION

LGE-CMRI is a useful tool for establishing whether such patients have definitive evidence of non-ST-segment elevation myocardial infarction (NSTEMI), and can make an important contribution to the long-term management strategy of these patients as an inappropriate diagnosis of NSTEMI carries important medical, social and financial implications.

A novel method for the detection of transient myocardial ischaemia using body surface electrocardiac mapping

BACKGROUND

The limitations of the 12-lead ECG in the detection of myocardial ischaemia are well known. This study sought to test the hypothesis that a Body Surface Mapping (BSM) system can detect and localise the transient regional ischaemia induced by elective percutaneous coronary intervention (PCI) in patients with stable angina.

METHODS AND RESULTS

25 patients undergoing elective single vessel PCI were studied: 11 with RCA lesions, 9 with LAD lesions and 5 with circumflex lesions. Patients had BSM readings every 30 s following the inflation of a dilating balloon in the target vessel for 1 min. BSMs were analysed for ST segment change at 60 ms after the J point (ST60). Peak ST changes were analysed and colour map reconstruction made. Characteristic ST segment changes in each arterial domain were observed following inflation of the balloon. Maximal change occurred in a standard V lead on only 2/46 occasions. Statistically significant rapid rise and fall of ST 60 readings were observed indicating the onset recovery and location of the transient ischaemia. A novel method for the presentation of colour map reconstruction that removes baseline noise has been developed.

CONCLUSIONS

These data confirm the hypothesis that this BSM system can detect and display transient myocardial ischaemia. BSM may represent a novel clinical tool for the assessment of clinical ischaemia.

Cardiac troponins

Cardiac troponins I and T are proteins integral to the function of cardiac muscle. They are very sensitive markers for the detection of myocardial damage, and the ability to assay their serum levels accurately and quickly have revolutionized the concepts of minor myocardial injury and infarction. They are also powerful prognostic indicators of future adverse cardiac events. Limitations, more of troponin T than I, include decreased specificity in renal failure and skeletal muscle disease. Rapid, whole blood assays are now available that can be done at the patient's bedside. This review discusses the cardiac troponins, their biochemistry, the assays for them currently available, and their roles in the evaluation of cardiac disease in the Emergency Department (ED).

Effect of leukocytosis at initial examination on prognosis in patients with primary unstable angina

BACKGROUND

Leukocytosis with acute myocardial infarction at initial examination predicts adverse prognosis, but it is unknown whether it predicts outcome in patients with primary unstable angina.

METHODS AND RESULTS

We studied 414 consecutive patients with unstable angina admitted through the emergency department to telemetry and intensive care units of an urban academic hospital. To study primary unstable angina, we excluded 134 patients with precipitants (eg, urosepsis, pneumonia) that may cause leukocytosis. Of 280 patients, 96 (34%) had leukocytosis (leukocyte count >10,000 per microL) at initial examination. A total of 30 patients (11%) died and 47 (17%) died or had nonfatal myocardial infarction within 12 months of initial examination. In a univariate Cox model, patients with leukocytosis had a hazard ratio (HR) of 2.6 (95% confidence interval [CI] 1.3-5.4) for death by 1 year. In a multivariate Cox model the only significant predictors of 1-year death were congestive heart failure at initial examination (HR 7.8; 95% CI 2.8-22) and elevated creatinine (HR 2.7; 95% CI 1.3-5.7); in this model, the relation between leukocytosis and prognosis was markedly attenuated (HR 1.4; 95% CI 0.6-2.9). The adjusted HR for leukocytosis was 1.3 (95% CI 0. 7-2.3) for death or nonfatal MI by 1 year.

CONCLUSIONS

Leukocytosis at initial examination is associated with adverse prognosis in patients with primary unstable angina. However, the association is confounded by other important predictors of prognosis. Leukocytosis may be a marker of stress associated with more severe cases of unstable angina or comorbid conditions.

Predictive value of C-reactive protein and troponin T in patients with unstable angina: a comparative analysis. CAPTURE Investigators. Chimeric c7E3 AntiPlatelet Therapy in Unstable angina REfractory to standard treatment trial

OBJECTIVES

We evaluated C-reactive protein (CRP) and troponin T (TnT) for predicting six-month cardiac risk in patients with unstable angina.

BACKGROUND

Troponin T is predictive of cardiac risk in patients with unstable angina. The clinical implications of elevated CRP in such patients remains controversial.

METHODS

Baseline TnT and CRP values were determined in 447 patients with unstable angina enrolled in the placebo group of the Chimeric c7E3 AntiPlatelet Therapy in Unstable angina REfractory to standard treatment trial (CAPTURE) trial. All patients underwent a coronary intervention and were followed for a six month period in which 13 deaths and 47 myocardial infarctions were documented (MIs).

RESULTS

Troponin T was >0.1 microg/liter in 30% and CRP was >10 mg/L in 41% of the patients. For the initial 72-h period (including coronary intervention), TnT (17.4% vs. 4.2%; p < 0.001) but not CRP (10.3% vs. 8%; p = 0.41) was predictive of mortality and MI. The TnT-positive patients displayed more frequent recurrent instability before the planned intervention (44.8% vs. 16.9%; p < 0.001), but in the CRP-positive patients, no such increase was observed (25.9% vs. 24.8%; p = 0.92). In contrast, for the six month follow-up period, CRP was predictive of cardiac risk (mortality, MI) (18.9% vs. 9.5%; p = 0.003). Using multivariate analysis, both CRP and TnT emerged as independent predictors of mortality and MI at six-month follow-up. Furthermore, the incidence of coronary restenosis during six-month follow-up was not related to TnT status (3% vs. 4.5%; p = 0.49); however, it was significantly related to CRP status (7% vs. 2.3%; p = 0.03).

CONCLUSIONS

Troponin T, but not CRP, was predictive of cardiac risk during the initial 72-h period, whereas CRP was an independent predictor of both cardiac risk and repeated coronary revascularization (coronary artery bypass graft surgery and percutaneous transluminal coronary angioplasty) during six month follow-up.

Markers of inflammation as predictors in cardiovascular disease

Recent research suggests that inflammation in the coronary arteries may be intimately involved in the development of atherosclerosis and its associated acute coronary syndromes. Experimental and clinical studies based on the biochemical markers of inflammation and vascular perturbation in plasma as well as in atherosclerotic tissue have provided substantial evidence of ongoing inflammation in coronary heart disease. These studies have suggested a potential role for biochemical markers of inflammation in the prediction of risk for the development of coronary heart disease as well as in the prediction of adverse cardiac-related outcomes in patients with known coronary syndromes. Markers of inflammation appear to offer risk prediction information that is independent of, and possibly complementary to, traditional risk factors for the development of cardiovascular disease. There are numerous potential markers for these inflammatory processes and their interdependence remains somewhat unclear. Clinical studies have investigated some, but not all of these markers in a critical and comparative fashion. Therefore, further well-designed prospective studies should elucidate the role of markers of inflammation in the prediction, diagnosis, and management of cardiovascular disease.

The health care burden of unstable angina

Worldwide, UA represents a significant allocation of resources. UA represents a syndrome where not only do many therapies exist, but considerable clinical trial evidence has accumulated. Universal application of effective practice patterns is warranted if we are to successfully reduce the burden of UA. Economic analyses cannot resolve many of the underlying societal issues that affect decision making. Often, the acceptability of an economic burden is dependent on the willingness of both individuals and society to pay. In an interesting study, Chestnut et al evaluated the willingness of 50 patients to pay for avoiding a worsening of their angina symptoms. On average, the patients were willing to pay between $210 and $499 to avoid four to eight additional angina episodes each month. The "rule of rescue" suggests that society is often willing to pay large sums of money to save those in extreme need, such as the 55-year-old man rushed to the emergency department clutching his chest. Only recently has attention been paid to how much this disease entity costs us. Whereas the 1980s and 1990s saw a focus on costs, the next century will increasingly focus on value--obtaining the best health outcome for the dollars spent. Debate has shifted, at least in part, from purely financial costs to medical effectiveness and outcomes management. Continuing assessments of value of interventions and application of evidence based-management strategies permit rational selection of therapy and allow us best to bear the burden of UA.