LOS ANGELES — Nearly one in nine patients admitted with an acute MI was seen shortly before the MI in the primary care setting with symptoms suggestive of acute cardiac ischemia, Dr. Thomas D. Sequist reported at the annual meeting of the Society of General Internal Medicine.
“We know from our own experience in Boston that missed diagnosis of MI in this setting is a rising source of malpractice claims,” said Dr. Sequist of Brigham and Women's Hospital.
The investigators identified 966 admissions for acute MI, of whom 106 (11%) had complained of symptoms typical of potential heart disease at their last outpatient visit. During the outpatient visit prior to the MI, chest pain and dyspnea accounted for more than three-quarters of all chief complaints. Other complaints included thoracic or epigastric pain, dizziness, weakness, or nausea.
This population-based case-control study used billing claims to identify admissions for acute MI from 2000 to 2004 among patients with no prior history of coronary heart disease (CHD). The 318 control patients were matched to cases on chief complaint and date of outpatient visit, but had no diagnosis of MI within the next 30 days.
Compared with controls, cases were older and were more likely to be male and to have diabetes or dyslipidemia. Approximately 50% of both cases and controls received an electrocardiogram (ECG). Not surprisingly, among those who had an ECG, the rates of normal results were much lower in cases than controls.
Despite having symptoms of possible CHD, few study participants in both groups received cardiac medications (aspirin, 11%; β-blockers, 7%). “There was a significant opportunity for more aggressive evaluation and treatment of these symptomatic patients,” Dr. Sequist said.
The Framingham Risk Score (FRS) predicts risk for developing CHD using information about coronary risk factors readily available in the outpatient setting, and may be used with asymptomatic individuals. In contrast, both the Diamond and Forrester Probability (DFP) and the Goldman Prediction Tool (GPT), which calculate risk scores that predict either CHD or MI, can only be used with individuals who have chest pain.
Cases had a nearly 20-fold greater likelihood of having a FRS greater than or equal to 10%, compared with controls (odds ratio, 19.5). Among patients whose FRS was greater than or equal to 10%, more than 30% were diagnosed with angina. Higher DFP and GPT scores were also associated with MI (odds ratio of 8.3 with a DFP score of 10% or more, and OR of 12.1 with a GPT greater than 7%). However, the FRS had the best sensitivity (85%) and specificity (75%) combination in those individuals at moderate risk.