Make the Diagnosis: Murmur, Systolic
Systolic murmurs are common, and echocardiography is normal in the majority of asymptomatic individuals with murmurs. Clinical evaluation offers the potential to identify those patients with increased likelihood of underlying structural disease and to avoid costly echocardiographic evaluation in all patients with systolic murmurs.
One study of randomly selected elderly Finnish persons (aged 75-86 years) found a prevalence of moderate to severe AS of 8.8% in women and 3.6% in men.10 The prevalence in younger patients ought to be less. The Framingham Heart Study showed that echocardiographic evidence of MR is common and a function of both age and sex.11 A useful approximation for the prevalence of mild to moderate MR is 15% from age 40 to 60 years for both men and women. After age 60, women have a prevalence of about 25% compared with men, who have an increasing frequency of MR that approximates 40% by age 80 years. The prevalence of MVP is about 2.5%.12, 13
Population for Whom a Systolic Murmur Should Be Assessed
It is sensible to listen for a systolic murmur in every patient for whom a complete cardiac database is necessary.
Once a patient with a systolic murmur is identified, the clinical examination helps identify those more likely to have significant underlying cardiac lesions. However, a cardiac echocardiogram is required to determine whether the finding represents a significant or less significant cardiac lesion.
The presence of a murmur can be heard with a variety of underlying lesions such as myocardial ischemia, endocarditis, and disturbances that cause a high flow rate.
Identifying Normal (Innocent) Murmurs
Cardiologists and emergency physicians are accurate at distinguishing abnormal from innocent murmurs (Tables 33-13 and 33-14).
Table 33-13Likelihood Ratio for the Overall Examination for Detecting Valvular Disease ||Download (.pdf) Table 33-13 Likelihood Ratio for the Overall Examination for Detecting Valvular Disease
| ||LR for Valvular Disease |
|LR+ (95% CI) ||LR– (95% CI) |
|Cardiologists5 ||38 (9.5-154) ||0.31 (0.18-0.52) |
|Emergency department physicians2 ||14 (10-19) ||0.21 (0.13-0.34) |
|Summary ||15 (11-20) ||0.25 (0.17-0.36) |
Table 33-14Likelihood Ratios of Individual Findings for Identifying Murmurs That Are Significant ||Download (.pdf) Table 33-14 Likelihood Ratios of Individual Findings for Identifying Murmurs That Are Significant
| ||LR for a Significant Systolic Murmura |
|Clinical Sign ||LR+ (95% CI) ||LR– (95% CI) |
|Systolic thrill (n = 8) ||12 (0.76-205) ||0.73 (0.58-0.93) |
|Holosystolic murmur (n = 26) ||8.7 (2.3-33) ||0.19 (0.08-0.43) |
|Loud murmur (n = 29) ||6.5 (2.3-19) ||0.08 (0.02-0.31) |
|Plateau-shaped murmur (n = 20) ||4.1 (1.4-12) ||0.48 (0.30-0.77) |
|Loudest at the apex (n = 30) ||2.5 (0.58-11)...|