Tonsil, appendix removal before age 20 associated with premature MI

Patients who have tonsillectomy or appendectomy before 20 years of age appear to be at increased relative risk for acute myocardial infarction (AMI) 15 to 20 years later, according to a recent study.

Researchers from the Karolinska Institute in Stockholm performed a prospective, matched cohort study involving Swedish residents who were born from 1955 through 1970. Data from a national register identified appendectomies and tonsillectomies. Each patient who had surgery was matched to 5 controls without history of either surgery.

All patients and controls were followed for AMI for an average of 23.5 years. The primary analysis focused on patients who had surgery before age 20 (54,449 appendectomies and 27,284 tonsillectomies). Secondary outcomes included total and cardiovascular mortality, stroke, and revascularization procedures.

The cumulative risk of AMI was low throughout the study. However, the occurrence of AMI was higher in patients than in controls. Patients undergoing tonsillectomy before age 20 had a 44% increased risk for AMI, and those who had appendectomy had a 33% increased risk. The average age for AMI was 39 for tonsillectomy patients and 38 for appendectomy patients. There was no link between surgery at age 20 or older and risk of AMI.

Tonsillectomy and appendectomy also were linked to an increased risk of total mortality, stroke, and revascularization procedures, but the association was weaker for cardiovascular mortality.

The researchers hypothesize that because the appendix and tonsils are secondary lymphoid organs, their removal could mediate immune activity that affects AMI risk. This effect appears most pronounced when both appendix and tonsils are removed, they say.

A major limitation of the study is that study participants were relatively young. Therefore, the results cannot be extrapolated to AMI cases in older persons who are at highest risk.

Janszky I, Mukamal KJ, Dalman C, Hammar N, Ahnve S. Childhood appendectomy, tonsillectomy, and risk for premature acute myocardial infarction-a nationwide population-based cohort study. Eur Heart J. 2011. Epub ahead of print.