Association between postoperative nadir platelet count and postoperative cardiovascular complications following septal myectomy in patients with hypertrophic cardiomyopathy: a retrospective cohort study

Background Platelet count is associated with cardiovascular risk and mortality in several cardiovascular diseases, but the association of the nadir platelet counts post-septal myectomy with the cardiovascular complication risk in hypertrophic obstructive cardiomyopathy patients remains unclear. Methods This retrospective cohort study reviewed all adult patients who underwent septal myectomy at a single tertiary referral center over a 5-year period. Postoperative nadir platelet count was defined as the lowest platelet count in the first 4 postoperative days or until hospital discharge. The composite outcome included cardiovascular death, myocardial infarction, heart failure, malignant arrhythmia, cardiac tamponade, and major bleeding events within 30 days postoperatively. Univariable and multivariable logistic regression and restricted cubic spline models were used to assess the association between postoperative nadir platelet count and the 30-day postoperative cardiovascular complication risk. Results Among the 113 enrolled patients, 23 (20.4%) developed cardiovascular events within 30 days postoperatively. The incidence of postoperative cardiovascular complications was significantly higher in patients with a nadir platelet count ≤ 99 × 10 9 /L than in those with a nadir platelet count > 99 × 10 9 /L (33.3% vs. 7.1%, crude risk ratio: 4.67, 95% confidence interval: 1.69–12.85, P < 0.001). Multivariable logistic regression revealed that postoperative nadir platelet count was negatively associated with 30-day postoperative cardiovascular complications (adjusted odds ratio: 0.97; 95% confidence interval: 0.95–0.99; P = 0.005) and the association was linear ( P nonlinearity = 0.058) after full adjustment. The association between nadir platelet count and cardiovascular complications within 30 days post-surgery was consistent in all predefined subgroups (P interaction > 0.05). Conclusion The postoperative nadir platelet count was significantly associated with the 30-day post-myectomy risk of cardiovascular complications in hypertrophic obstructive cardiomyopathy patients. Trial registration This trial was registered at ClinicalTrials.gov (NCT04275544).