Surgical Treatment of Bacterial Endocarditis

Bacteriological Outcome after Valve Surgery for Active Infective Endocarditis: Implications for Duration of Treatment after Surgery

BACKGROUND

There has been no systematic evaluation of outcome after surgery for infective endocarditis with respect to duration of antibiotic treatment.

METHODS

We performed a retrospective chart review of episodes of valve surgery for active infective endocarditis at Green Lane Hospital (Auckland, New Zealand) for 1963-1999. We recorded the duration of antibiotic treatment before and after valve surgery; the extent of infection at operation; Gram stain, culture, and histopathological testing results for valve samples; and the bacteriological outcome after surgery. The primary outcome measure was relapse, defined as endocarditis due to the same species within 1 year after surgery.

RESULTS

For the 358 patients in our study, the median duration of follow-up was 4.8 years. Thirty-two patients (9%) had 36 subsequent episodes of endocarditis. Relapse occurred after 3 (0.8%) of the operations (95% CI, 0.2%-2.0%). Relapse of infection was unrelated to the duration of antibiotic treatment before or after surgery, positive valve culture results, positive Gram stain results, or perivalvular infection. Since 1994, we have reduced the duration of antibiotic treatment by approximately 7 days for those with positive valve culture results and by approximately 14 days for those with negative valve culture results, without any increase in the number of relapses.

CONCLUSIONS

Relapse is an uncommon event following surgery for endocarditis. Commonly suggested indications for prolonging postoperative treatment are not associated with higher relapse rates, and their relevance is debatable. We conclude that it is unnecessary to continue treatment for patients with negative valve culture results for an arbitrary 4-6-week period after surgery. Two weeks of treatment appears to be sufficient, and, for those operated on near the end of the standard period of treatment, simply completing the planned course should suffice.

Gram stain, culture, and histopathological examination findings for heart valves removed because of infective endocarditis

Retrospective chart review was undertaken for 480 patients who underwent a total of 506 valve replacements or repair procedures for infective endocarditis. The influence of preoperative antimicrobial treatment on culture, Gram stain, and histopathological examination findings for resected valve specimens was examined. When valves were removed before the end of treatment, organisms were seen on the Gram stain of ground valve material performed in the microbiology laboratory and on Gram-stained histopathological sections in 231 (81%) of 285 and 140 (67%) of 208 specimens, respectively (P=.0007). Gram-positive cocci were either cultured from or observed in excised valve tissue in 42 (67%) of 63 episodes involving negative preoperative blood cultures. Positive Gram stain results for microbiological specimens should be reintroduced into the definite pathological criteria for infective endocarditis. When deciding on how long to continue antimicrobial therapy after valve replacement for endocarditis, valve culture results should be the only laboratory finding taken into account, because it takes months for dead bacteria to be removed from sterile vegetations.

A case for early surgery in native left-sided endocarditis complicated by heart failure: results in 203 patients

From January 1982 to December 1988, 203 consecutive patients were selected for early valve replacement (mean 10 days from time of admission) if they had clinical evidence of native valve endocarditis with 1) vegetations on echocardiography, 2) severe valvular lesions, and 3) heart failure. Surgery was performed within 7 days of admission in 56% of patients and was done urgently because of hemodynamic deterioration in 108 (53%). All vegetations were identified by echocardiography and confirmed macroscopically at surgery. One hundred ten patients had isolated aortic valve infection, 50 had isolated mitral valve infection (p less than 0.05 for aortic vs. mitral) and 43 had double-valve infection. Mean aortic cross-clamp time was 57, 38 and 67 min, respectively. Sixty-four patients (32%) had extensive infection involving the anulus or adjacent tissues, or both; such infection more frequently involved the aortic than the mitral valve (p less than 0.05). Thirty-eight patients (35%) with aortic valve infection had abscess formation compared with 1 patient (2%) with mitral valve infection (p less than 0.05). Only eight patients (4%) died in the hospital. There were seven patients (3%) with a periprosthetic leak and five patients (3%) with early prosthetic valve endocarditis. Long-term follow-up, available in 174 hospital survivors (89%), revealed 10 deaths and two new ring leaks at 38 +/- 22 months. In conclusion, among patients with endocarditis who need surgery for heart failure, aortic valve infection is more prevalent than mitral valve infection and is more often associated with extensive infection, including abscess formation.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial endocarditis in patients with native or prosthetic heart valves: bacteriological and clinical findings

The clinical course of 12 episodes of native valve endocarditis (NVE) and 15 episodes of prosthetic valve endocarditis (PVE) was studied. The mortality in NVE was 3/12 episodes and in PVE 5/15. No significant differences in prognosis were observed in relation to the bacterial taxonomy, which was stated in all cases. Though surgical valve replacement was performed on the relative indications heart failure, resistance to treatment, or major embolism, the regimen was primarily conservative, and the results comparable to the reports in the literature of a more surgically active attitude.

Indications for cardiac surgery in patients with active infective endocarditis

Currently, absolute indications for valve replacement during active infective endocarditis include severe heart failure, the presence of an infecting microorganism that is not susceptible to available antimicrobial agents, and, in patients with an infected prosthetic valve, an unstable device. Relative indications include an etiologic microorganism other than a susceptible Streptococcus, relapse after presumed effective therapy, evidence of intracardiac extension of the infection, two or more systemic emboli, vegetations large enough to be demonstrated by echocardiography, and, in patients with an infected prosthetic device, early disease and periprosthetic leak. With use of data from the medical literature, a study generated by the cardiovascular surgical group at the University of Alabama School of Medicine, and a brief cost analysis, a point system was constructed to assist in decision-making concerning surgery in patients with active infective endocarditis. The usefulness of this system will depend on experience generated from its utilization in a larger number of patients as well as new data relative to a more complete understanding of the risks and benefits of surgery in this condition.